Freud (V1.3) “Report on My Studies in Paris and Berlin” in Standard Edition of the Complete Psychological Works, notes and quotes

 

by Corry Shores

 

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[The following is not summary. It simply catalogs particular parts of the text that I take note of, with a brief summary of all these notes. Proofreading is incomplete, so please forgive all my various mistakes. Section divisions are my own and do not reflect partitions in the text.]

 

 

 

Notes and Quotes from

 

Sigmund Freud

 

Standard Edition of the Complete Psychological Works

 

Volume 1

(1886-1889)

Pre-Psycho-Analytic Publications and Unpublished Drafts

3

“Report on My Studies in Paris and Berlin”

(1956 [1886])

 

 

 

 

 

Very brief summary of these notes:

Freud’s text, “Report on My Studies in Paris and Berlin,” provides an account of his studies at the Hospice de la Salpêtrière in Paris under Jean-Martin Charcot, who was using hypnotism and other means to greatly advance our knowledge of the neurosis hysteria. Freud was impressed by how Charcot was dealing with illnesses that have somatic symptoms but no obvious somatic causes. In other words, they seem more to be diseases of the psyche than strictly of the body. As a result of these studies, Freud’s research interests turned away from neuroanatomy toward psychopathology.

 

 

 

Brief summary of these notes (collecting those below):

(3.1) Editor’s Note: Freud began as a medical student interested in neuroanatomy. In 1885-1886, he studied abroad, in France, with a grant from his school, Vienna University. During his intellectual explorations, especially under the influence of Jean-Martin Charcot, Freud’s interests change from neurology to psychopathology. This text is important for giving us insight into that fateful turn in the history of human culture. (3.2) Freud used his traveling grant to study neuropathology at the Hospice de la Salpêtrière. One thing that attracted him about this school was Jean-Martin Charcot, who was “inclined to study rare and strange material.” Freud’s initial research interests were “anatomical problems” (namely,  “the secondary atrophies and degenerations that follow on affections of the brain in children.”) However, Freud found that the laboratory for these studies was inadequate, so he switched to studying  something else (namely, “the relations of the nuclei of the posterior column in the medulla oblongata.”) At the same time, Freud became deeply impressed by Charcot’s teachings on neuropathology and began to study almost exclusively under him. (3.3) Charcot claimed that our knowledge of anatomy and of organic diseases was nearly complete, and what remained to be studied were the neuroses (in other words, diseases with no obvious physiological cause). Among the neuroses, Charcot specialized in hysteria. Historically, this illness had been poorly studied up until then. Charcot demonstrated that its causes are not so strongly linked to the genitals (for, it was long thought to be linked to the uterus), because it occurs in men too, who may have traumatic hysteria. He also determined the precise physiological symptoms for properly diagnosing hysteria. (3.4) Charcot also used hypnotism to arrive “at a kind of theory of hysterical symptomatology.” He treated it with full scientific rigor. At the same time, it was amazing to behold, and Freud was deeply impressed by the technique.

 

 

 

 

Contents

 

Text Information

 

3.1

[Editor’s Note: This Text as Marking Freud’s Turn from Neurology to Psychopathology]

 

3.2

[Freud’s Initial Anatomical Interests and His Attraction to Charcot’s Teachings]

 

3.3

[Charcot’s Advancing the Studies on Hysteria]

 

3.4

[Charcot’s Amazing and Scientific Use of Hypnotism]

 

Bibliography

 

 

 

 

 

Text Information

BERICHT ÜBER MEINE MIT UNIVERSITÄTS-JUBILÄUMS REISESTIPENDIUM UNTERNOMMENE STUDIENREISE NACH PARIS UND BERLIN

(a) German Edition:

(1886 Date of composition.)

1960 In J. and R. Gicklhorn’s Sigmund Freuds akademische Laufbahn im Lichte der Dokumente, 82, Vienna.

 

(b) English Translation:

‘Report on my Studies in Paris and Berlin’

1956 Int. J. Psycho-Anal., 37 (1), 2-7. (Tr. James Strachey.)

The present translation is a slightly corrected reprint of the one published in 1956.

(3)

 

 

 

Summary

 

3.1

[Editor’s Note: This Text as Marking Freud’s Turn from Neurology to Psychopathology]

 

[Editor’s Note: Freud began as a medical student interested in neuroanatomy. In 1885-1886, he studied abroad, in France, with a grant from his school, Vienna University. During his intellectual explorations, especially under the influence of Jean-Martin Charcot, Freud’s interests change from neurology to psychopathology. This text is important for giving us insight into that fateful turn in the history of human culture.]

 

The editor, James Strachey, says that Freud’s report here marks  “a historic event: the diversion of Freud's scientific interests from neurology to psychology” (3). Freud is reporting on his accomplishments during a trip funded by Vienna University in 1885 (p.3), where he was studying medicine. He finished writing the report on the 22nd of April, 1886 (p.3). This text gives us insight into the way that Freud’s interests turned from neuroanatomy to psychopathology, by means of his work with Jean-Martin Charcot at the Pitié-Salpêtrière Hospital. Strachey marks that turning point as happening early December, 1885.

The high importance which Freud himself always attributed to his studies under Charcot is a matter of common knowledge. | This report marks his experience at the Salpêtrière with the utmost clarity as a turning point. When he arrived in Paris, his ‘chosen concern’ was with the anatomy of the nervous system; when he left, his mind was filled with the problems of hysteria and hypnotism. He had turned his back on neurology and was moving towards psychopathology. It would even be possible to assign a precise date to the change – in early December, 1885, when he ceased his work in the pathological laboratory of the Salpêtrière; but the inconvenient arrangements at that laboratory, which he himself puts forward as the explanation, were, of course, no more than a precipitating cause of the momentous shift in the direction of Freud's interests. Other and deeper factors were at work, and among them, no doubt, the great personal influence which Charcot evidently exercised on him.

(3-4)

[contents]

 

 

 

 

 

 

3.2

[Freud’s Initial Anatomical Interests and His Attraction to Charcot’s Teachings]

 

[Freud used his traveling grant to study neuropathology at the Hospice de la Salpêtrière. One thing that attracted him about this school was Jean-Martin Charcot, who was “inclined to study rare and strange material.” Freud’s initial research interests were “anatomical problems” (namely,  “the secondary atrophies and degenerations that follow on affections of the brain in children.”) However, Freud found that the laboratory for these studies was inadequate, so he switched to studying  something else (namely, “the relations of the nuclei of the posterior column in the medulla oblongata.”) At the same time, Freud became deeply impressed by Charcot’s teachings on neuropathology and began to study almost exclusively under him.]

 

[ditto]

In my application for the award of the Travelling Bursary from the University Jubilee Fund for the year 1885-6, I expressed my intention of proceeding to the Hospice de la Salpêtrière in Paris and of there continuing my studies in neuropathology. Several factors had contributed to this choice. [...] there was the great name of J.-M. Charcot, who has now been working and teaching in his hospital for seventeen years.

(5)

In consequence of the scarcity of any lively personal contact between French and German physicians, the | findings of the French school – some of them (upon hypnotism) highly surprising and some of them (upon hysteria) of practical importance – had been met in our countries with more doubt than recognition and belief; and the French workers, and above all Charcot, were obliged to submit to the charge of lacking in critical faculty or at least of being inclined to study rare and strange material and to dramatize their working-up of that material. Accordingly, when the honourable College of Professors distinguished me by the award of the Travelling Bursary, I gladly seized the opportunity which was thus offered of forming a judgement upon these facts based on my own experience [...].

(5-6)

J.-M. Charcot, when he was an ‘interne’ at the Salpêtrière in 1856, perceived the necessity of making chronic nervous diseases the subject of constant and exclusive study, and he determined to return to the Salpêtrière as a médecin des hôpitaux and never thereafter to leave it.

(7)

The man who is at the head of all these resources and auxiliary services is now sixty years of age. He exhibits the liveliness, cheerfulness, and formal perfection of speech which we are in the habit of attributing to the French national character; while at the same time he displays the patience and love of work which we usually claim for our own nation. The attraction of such a personality soon led me to restrict my visits to one single hospital and to seek instruction from one single man. I abandoned my occasional attempts at attending other lectures after I had become convinced that all they had to offer were for the most part well-constructed rhetorical performances. The only exceptions were Professor Brouardel's forensic autopsies and lectures at the Morgue, which I rarely missed.

(8)

My work in the Salpêtrière itself took on a different shape from what I had originally laid down for myself. I had arrived with the intention of making one single question the subject of a thorough investigation; and since in Vienna my chosen concern had been with anatomical problems, I had selected the study of the secondary atrophies and degenerations that follow on affections of the brain in children.

(8)

The laboratory was not at all adapted to the reception of an extraneous worker, and such space and resources as existed were made inaccessible owing to lack of any kind of organization. I thus found myself obliged to give up anatomical work³ and rest content with a discovery concerned with the relations of the nuclei of the posterior column in the medulla oblongata.

(8)

3. [This was at the beginning of December, 1885 (Jones. 1953, 231)].

(8)

Jones, E. (1953) Sigmund Freud: Life and Work, Vol. 1, London and New York. (Page references are to the English edition.) (xvii, 3, 8, 9, 15, 20, 24, 64, 157, 175-6, 213, 262, 284, 290)

(409)

In contrast to the inadequacy of the laboratory, the clinic at the Salpêtrière provided such a plethora of new and interesting material that it needed all my efforts to profit by the instruction which this favourable opportunity afforded. The weekly timetable was divided as follows. On Mondays Charcot delivered his public lecture, which delighted its hearers by the perfection of its form, while its subject-matter was familiar from the work of the preceding week. What these lectures offered was not so much elementary instruction in neuropathology as information, rather, on the Professor's latest researches; and they produced their effect primarily by their constant references to the patients who were being demonstrated. On Tuesdays Charcot held his ‘consultation externe’, at which his assistants brought before him for examination the typical or puzzling cases among the very large number attending the out-patient department.

(9)

[contents]

 

 

 

 

 

 

3.3

[Charcot’s Advancing the Studies on Hysteria]

 

[Charcot claimed that our knowledge of anatomy and of organic diseases was nearly complete, and what remained to be studied were the neuroses (in other words, diseases with no obvious physiological cause). Among the neuroses, Charcot specialized in hysteria. Historically, this illness had been poorly studied up until then. Charcot demonstrated that its causes are not so strongly linked to the genitals (for, it was long thought to be linked to the uterus), because it occurs in men too, who may have traumatic hysteria. He also determined the precise physiological symptoms for properly diagnosing hysteria.]

 

[ditto]

Charcot used to say that, broadly speaking, the work of anatomy was finished and that the theory of the organic diseases of the nervous system might be said to be complete: what had next to be dealt with was the neuroses. This pronouncement may, no doubt, be regarded as no more than an expression of the tum which his own activities have taken. For many years now his work has been centred almost entirely on the neuroses, and above all on hysteria, which, since the opening of the outpatient department and of the clinic, he has had an opportunity of studying in men as well as women.

I will venture to sum up in a few words what Charcot has achieved in the clinical study of hysteria. Up to now, hysteria can scarcely be regarded as a name with any well-defined meaning. The state of illness to which it is applied is only character- | ized scientifically by negative signs; it has been studied little and unwillingly; and it labours under the odium of some very widespread prejudices. Among these are the supposed dependence of hysterical illness upon genital irritation, the view that no definite symptomatology can be assigned to hysteria simply because any combination of symptoms can occur in it, and finally the exaggerated importance that has been attributed to simulation in the clinical picture of hysteria. During the last few decades a hysterical woman would have been almost as certain to be treated as a malingerer, as in earlier centuries she would have been certain to be judged and condemned as a witch or as possessed of the devil. In another respect there has, if anything, been a step backward in the knowledge of hysteria. The Middle Ages had a precise acquaintance with the ‘stigmata’ of hysteria, its somatic signs, and interpreted and made use of them in their own fashion.

(11)

In his study of hysteria Charcot started out from the most fully developed cases, which he regarded as the perfect types of the disease. He began by reducing the connection of the neurosis with the genital system to its correct proportions by demonstrating the unsuspected frequency of cases of male hysteria and especially of traumatic hysteria. In these typical cases he next found a number of somatic signs (such as the character of the attack, anaesthesia, disturbances of vision, hysterogenic points etc.), which enabled him to establish the diagnosis of hysteria with certainty on the basis of positive indications.

(11)

[contents]

 

 

 

 

 

 

3.4

[Charcot’s Amazing and Scientific Use of Hypnotism]

 

[Charcot also used hypnotism to arrive “at a kind of theory of hysterical symptomatology.” He treated it with full scientific rigor. At the same time, it was amazing to behold, and Freud was deeply impressed by the technique.]

 

[ditto]

By making a scientific study of hypnotism – a region of neuropathology which had to be wrung on the one side from scepticism and on the other from fraud – he himself arrived at a kind of theory of hysterical symptomatology.

(11)

Nor did I neglect the opportunity of acquiring a personal acquaintance with the phenomena of hypnotism, which are so astonishing and to which so little credence is attached, and in particular with the ‘grand hypnotisme’ [‘major hypnotism’] described by Charcot. I found to my astonishment that here were occurrences plain before one’s eyes, which it was quite impossible to doubt, but which were nevertheless strange enough not to be believed unless they were experienced at first hand. I saw no sign, however, that Charcot showed any special preference for rare and strange material or that he tried to exploit it for mystical purposes. On the contrary, he regarded hypnotism as a field of phenomena which he submitted to scientific description, just as he had done many years before with multiple sclerosis or progressive muscular atrophy. He did not seem to me to be at all one of those men who marvel at what is rare rather than what is usual; and the whole trend of his mind leads me to suppose that he can find no rest till he has correctly described and classified some phenomenon with which he is concerned, but that he can sleep quite soundly without having arrived at the physiological explanation of that phenomenon.

I have given considerable space in this Report to remarks on hysteria and hypnotism because I had to deal with what was completely novel and the subject of Charcot’s own particular studies.

(13)

[contents]

 

 

 

 

 

 

 

 

 

 

Bibliography:

 

Freud, Sigmund. “Report on My Studies in Paris and Berlin” (1956 [1886]). In The Standard Edition of the Complete Psychological Works, Vol. 1, (1886–1899): Pre-Psycho-Analytic Publications and Unpublished Drafts, edited and translated by James Strachey, 1–15. London: Hogarth, 1966.

.

 

 

.

Heywood & Zihl (1999) Case Study of L.M.’s Inability to Perceive Motion, in their book chapter “Motion Blindness”, summary notes

by Corry Shores
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Heywood and Zihl

“Motion Blindness”

Brief Summary:

L.M. is a woman who suffered a rare case of brain damage that resulted in her being unable to detect motion. She could see the different positions of moving objects but not the motion between them. Motion in place, like the stream of pouring water, seemed “frozen like a glacier”. I appeal to this case for the phenomenological argument that motion, change, and time itself are differential phenomenon: the phenomenal content is not just the different positions of a moving object, for example, but as well, the difference between them is itself phenomenal content. In other words, time and change phenomenologically speaking are differences and not objects or processes.

Summary

Neurophysiological studies indicate that our vision system has highly specialized parts.

The discovery of an impressive patchwork of cortical visual areas that lies in the extrastriate cortex of the monkey has led to the suggestion that each is relatively specialised for the processing of a particular visual attribute.
[1]

Thus, “the destruction of a single area will result in the disturbance of a single function.” [2a] But there are problems with this view. For example, already we have discovered 30 or so areas of  the macaque monkey brain used for vision, but there are not that many visual attributes which each one might specialize in. Also, there is no good way to make such a correlation [as the are regional variations which complicate such an analysis]. The second problem is that we have only identified a small  number of selective disorders [and so we cannot identify all the possible regions], and thirdly, “surgical removal of a single visual area in the monkey has rarely, if ever, resulted in a deficit that parallels any of the clinical findings.” [2]

Nonetheless, we still have cases of selective disorders that are useful to our scientific investigation into the brain’s visual areas.

There is a particularly important part of the brain for vision (found in the monkey brain). It is the cortical area V5, also known as MT. Research on this area indicated that the visual cortex of monkey brains has highly specialized parts. Regarding this V5 region of the visual cortex, “Neurons in this region are finely tuned to the direction of visual motion and it was promptly referred to as ‘the motion area.’” [2d] And shortly after this discovery there was a case study of a patient (L.M.) “with a relatively selective and profound deficit in the perception of visual motion […] (Zihl, von Cramon, & Mai, 1983)”. [3a]

The Case of L.M.

Patient L.M. had a brain injury that seemed to have disabled her ability to perceive motion (the injury occurred 1978, studies on her case began 1980, and Zihl et al. publish their report 1983). She could see the positions of mobile things but never the movements between those positions.

L.M. reported that looking at objects in motion made her feel quite unwell. The explanation she gave sounded rather odd. She claimed that she no longer saw movement; objects which should move, as she well remembered, now appeared as "restless" or “jumping around". Although she could see objects at different locations and distances, she was unable to find out what happened to them between these locations. She was sure that objects did not move, but appeared as "jumping from one position to the next, but nothing is in between''. Because of' these difficulties she avoided streets, busy places, supermarkets and cafés. Traffic had become very frightening; she could still identify cars without any difficulty but could not tell whether they were moving or stationary. The only w:ay for her to establish this was to wait until the car became either conspicuously bigger or small. However, this turned out to be very complicated, especially when there were other cars in the vicinity. As a consequence, she no longer risked crossing the street except at pedestrian crossings. When people walked nearby, she usually waited until they passed, because the ''restlessness"' they produced by their walking irritated her so much that she had to interrupt her walking to find a "resting point for my eyes". Furthermore, she reported substantial difficulty in pouring fluids into a cup or glass, because the tea, coffee or orange juice appeared "frozen like a glacier'. She could not see the fluid rising, and therefore, couldn't establish when to stop pouring. In addition, she felt very irritated when looking at people while they were speaking: their lips appear to ''hop up and down", so she had to look away so as not to become confused. "'To my friends, this behavior appears very strange if not unkind; they believe that I am no longer interested in their conversation because I am always looking absent-minded. But it is the only way to listen to them without being disturbed". For this reason she had decided no longer to meet her friends.
[3]

Behavior Consequences of L.M.’ Movement Vision Disorder

In this section L.M. is quoted as saying:

“Sometimes I do not even know whether a person is approaching me or is receding.”
[6a]

Neuropsychological Assessment

In this section we learn that since L.M.’s case, there have been a number of other reported cases of deficits in motion perception. However, L.M. is still the case most extensively studied. Her condition has been coined akinetopsia by Zeki (1991)

Cerebral Akinetopsia

There is an effective test for the brain’s motion systems called ‘random dot cinematograms.’

one very effective way of establishing the capacity of the motion system is by testing with a class of visual stimuli known as random dot cinematograms. These are composed of a random display of elements which lack an overall conspicuous form. When some of the dots are spatially displaced during sequential frames of the display, the normal observer effortlessly perceives smooth visual motion. By varying the parameters of the display, such as the density, distributions of direction and distance of the displaced elements, exposure duration and interstimulus interval, the limits of motion vision can be characterised. The displays have the particular advantage that the observer is unable to determine which element in the second exposure corresponds to which element in the second [sic?]. It is therefore impossible to infer the motion from the change in location of individual elements. Processes that extract such motion have been termed “short-range” (Braddick, 1974), in contrast to longer-range processes that extract motion information from displays that contain small numbers of clearly defined elements.

[“Random Dot Kinematogram” animated gif from wikimedia commons]

Using this test, it was determined that at certain levels of variation, L.M. could not perceive motion.

Besides being unable to detect motion at a certain level, she was also unable to discriminate other properties of motion such as direction or velocity also at a certain level. “Even at low velocities, L.M. required a twenty-fold increase in contrast, compared with the normal observer, to correctly judge the direction of motion.” [9a] However with other testing it was determined that her deficit was not “in the direction of motion but in making judgments of the attributes of stimulus motion.” [9a]

Heywood, C. A., & Zihl, J. (1999). Motion blindness. In G. W. Humphreys  (Ed.), Case Studies in the Neuropsychology of Vision (pp. 1-16). Hove: Psychology Press.
Summary based on limited preview at google books:
http://books.google.com.tr/books?id=YyahncBD_FMC&printsec=frontcover

Random Dot Kinematogram animated gif from:
Wikipedia commons
Random Dot Kinematogram (Elliptical).gif
http://commons.wikimedia.org/wiki/File:Random_Dot_Kinematogram_%28Elliptical%29.gif

Weichselgartner & Sperling (1985) ‘Continuous Measurement of Visible Persistence’, notes

by Corry Shores
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[The following is summary and quotation except for my bracketed commentary. Please consult the original text, as not all of this article was clear to me.]

Erich Weichselgartner; George Sperling

‘Continuous Measurement of Visible Persistence’

Brief Summary:

The authors conduct experiments meant to determine the duration of visual persistence, and they introduce the notion of ‘perceived brightness’, which might be similar to the concept of ‘presentedness’ in the phenomenological study of the specious present.

Notes:

The authors will examine the decay of persisting visual images.

A brief visual stimulus presented to a subject is not perceived to end abruptly but to fade out gradually.
[p.711]

There have been two primary ways that the duration of persisting images have been tested: 1) inferring from the accuracy of subjects’ reports, and 2) depending on subjects’ subjective reports of their experiences.

The time difference between the physical termination of the stimulus and its perceptual termination has been investigated in a variety of paradigms. These paradigms fall into two main classes: those that infer visual storage from the accuracy of subject's reports and those that depend on subjective reports (e.g., Brindley's [1960] Class A and Class B procedures).
[711]

The first type (accuracy procedures) are generally either partial report tasks or picture completion tasks. In partial report (like Sperling 1960), the subject views a flash of a matrix of letters and must report on a randomly selected portion. In picture completion, subjects must compare successive images.

In the partial report paradigm (Sperling, 1960), the observer views a brief flash of a matrix of letters. Afterwards, a tonal cue that can be precisely located in time is used to request report of a randomly selected row of the stimulus. The decline of response accuracy with cue delay indicates the duration of short-term visual storage (iconic memory— Neisser, 1967). Picture completion paradigms require the observer to integrate information from two successive flashes in order to identify a target letter (e.g., Eriksen & Collins, 1967) or to detect a missing dot in a regular dot matrix (Hogben & DiLollo, 1974).
[711]

In subjective procedures, the subject makes their own judgment to how long the stimulus remains in their sensory memory. They can do this by adjusting clicking sound [see section 2.3 of Sperling 1967] [711B]

For the most part, both these objective and subjective methods indicate a similar duration for sensory memory. However, there are some important discrepancies. [Please see the last full paragraph of p.711, as it is not clear to me how to summarize it. It suggests that there is a function to describe the decay curve, but “no one has come up yet with a measure for those decay functions.” (712Aa)]

WS then distinguish two classes of studies on visible persistence. (a) Studies that are “concerned with the the time difference between stimulus termination and perceptual termination”, and (b) “studies concerned with the total phenomenal duration of the stimulus that require reliable judgments of both onset and termination, the estimated stimulus duration being the time difference between judged onset and termination”. [712Aa.b] However, “There are no statements concerning the actual form of the rise and decay curves or of the complete representation of the stimulus as a function of time in the subject's visual system.” [712Ab]

Thus what is needed is “a method to measure the entire moment-to-moment time course of visible persistence.” [712A] But, the term ‘visible persistence’ already has various meanings. So WS will use another term to be more specific: temporal brightness response (TBR), which “describes how the perceived brightness of a brief visual stimulus changes as a function of time.” [712A] [note, this could be similar to the notion of presentedness in the phenomenology of the specious present.] “The purpose of this article is to prove the feasibility of measuring the TBR and to measure TBRs to brief flashes for 3 observers.” [712A]

Elaborated Synchrony Judgment Paradigm

The following will be an elaboration of Sperling’s (1967) method. It will be an “intermodal synchrony judgment paradigm.” [712A] In it, the subject views two adjacent stimuli: (a) a reference stimulus that is “presented at the beginning of the trial and remains on with constant luminance during the trial,” and (b) “a test stimulus of varying luminance, which is presented and terminated sometime during the middle of the trial. Luminances are are adjusted so that from the observer's point of view the test stimulus initially appears dimmer than the steady-state reference stimulus but increases in intensity until eventually it becomes as bright or brighter (Figure 1).” [712A]

[As we can see, the luminosity of the test image will become at least as bright as the test image, maybe even brighter.] The instant when the luminosity seems to match between test and reference stimuli is called the match time. This method wants to know when the match time occurs. “In a time interval around match time, the subject is presented with a click.” [712Ba]

If the subject perceives the click before they perceive the two stimuli matching, they indicate with a left-hand response key. But if the click occurs after they seem to match, then with a right-hand response key. [712B]

Or, the subject might be asked to press the right-hand key if at the time of the click the test was brighter than the reference stimulus. Otherwise [if it seemed the same or dimmer] then they press the left-hand key.  [If the test is dimming and they press the right-hand key, then this would suggest the brightness persisted beyond its actual luminance.]

Repeated judgments result in a psychometric function, the probability of a right response as a function of time. The point of subjective equality (pse) is the 50% point of the psychometric function; it corresponds to the time at which the brightness of the reference matches that of the test. A psychometric function obtained with a particular luminance of the reference stimulus determines only one match time. The entire TBR function is obtained by obtaining match times for a full range of luminances of the reference stimulus, and by determining match times near the onset and also near the termination of the test stimulus.
[712B]

Verification Procedure

[The actual stimulus change has a luminance function, its change over time.] They will for example have a light bulb increase linearly to its maximum at 300 ms, then dim to off in another 300 ms. While the stimulus is rising, WS expect the match times to increase with increasing luminance.

Our primary interest is in the TBR function of a very brief stimulus. However, it is important to first demonstrate that a subject can make reasonable match time judgments with a slowly varying stimulus for which the TBR can be assumed to approximately track the temporal luminance function of the physical stimulus. An example of such a physical stimulus is the gradual fading out of a light bulb turned off with a dimmer. Therefore, we first determine TBRs for a control condition in which test field luminance increases linearly during a 600-ms period, stays at its maximum for 300 ms, and then turns off linearly during another 600-ms period. The data from this control condition with real "physical persistence" can be used to evaluate the method. For example, when the rising part of the test stimulus is under investigation (onset trials), we expect the match times to increase with | increasing luminance of the reference stimulus, and when the decaying part of the test stimulus is under investigation (termination trials), we expect the match times to increase with decreasing luminance of the reference stimulus. After Experiment 1 (with ramped onsets and terminations) we proceed to Experiment 2, which determines TBRs for brief stimuli. [712-713]

General Method

Overview

There are two experiments, the verification and the main experiment. Both use the same apparatus and a similar method.

Apparatus and Stimuli

Spatial arrangement

Spatial Arrangement:

As depicted in figure 2, the stimuli were two square-wave gratings.

Stimulus intensity:

Reference took on 5 different luminances [see table 1].

Procedure

Individual trials:

(1) Reference stimulus first turned on. (It remains on for 3,000 ms)

(2) Secondly, the test stimulus is turned on. (It remains on for 1,500 ms in Experiment 1, and 31 ms in experiment 2.)

(3) Click sounds. “On the first trial, the onset time of the click was randomly chosen within an interval of ± 200 ms around starting points (initial values), which were determined in preliminary experiments (see below).”

(4) Afterward, subject must decide whether click occurred before or after the instant of perceived brightness match between two visual stimuli. Either click before or click after choices available. [714B]

Blocks of trials:

Ran a number of trials varying brightness according to step procedure (below).

Staircase procedure:

WS used the stair-case procedure described by Lewitt (1971) [Please see the original article to be sure of its content. As far as I can summarize, it seems the problem that WS are contending with is that the subject cannot just press a button when it seems the stimuli match. For, this involves a motor response whose accuracy might be unreliable and variable. To narrow down to greater accuracy, WS suggest this step method. In it, the subject reports only after the stimuli have finished. The subject reports if the clicked seemed to come before or after the apparent match. If before, then the click is moved forward a step. If after, then moved back. It then seems by means of calculating this data, it can then be better approximated when it is that the subject perceives the match. The following diagram is from Levitt (1971) and it depicts this step ‘staircase’ procedure:

]

Experiment 1

Experiment 1 consisted of two phases. In Phase 1, stimulus parameters for Phase 2 were empirically determined. In Phase 2, the TBR for a ramped test stimulus was measured using the parameters from Phase 1.
[715A]

Method

Procedure

Phase 1:

The first phase determines appropriate luminances for the reference stimuli and also time for occurrence's of the click. They used the step method.

Together, the isolated brightness and temporal matches of Phase 1 pinpoint the brightness and time of the perceived brightness peak of the test stimulus.
[715]

Phase 2:

[Recall that “temporal brightness response (TBR)” “describes how the perceived brightness of a brief visual stimulus changes as a function of time.” (712A)]

In Phase 2 of Experiment 1, the TBR was determined for a ramped test stimulus by means of the psy -|- chophysical method described above in the Procedure section.
[715|716]

Results

The results of Experiment 1 can be found in table 1. Figure 3 shows the temporal brightness response times for the 3 subjects. The match times are open squares. “The five data points on the left side of the TBR are the match times for the onset judgment, and the five data points on the right side of the TBR are the match times for the termination judgment.” [716A, see for more detail]

The TBRs are comparable to the stimulus slopes. “In all cases of the onset judgment, the match times were ranked in an ascending order with increasing luminance, and in all cases of the termination judgment, the match times were ranked in an descending order with decreasing luminance.” [716B]

Discussion

[See text pp.176-178]

Conclusion:

From the results of Experiment 1, we conclude that the elaborated synchrony judgment method yields reasonable temporal brightness response functions, and there are pronounced individual differences.
[718B]

Experiment 2

Experiment 2 applies the paradigm of Ex1 to a 31ms flash to determine its TBR.

Method

Procedure

Phase 1:

A reference stimulus was found whose intensity matched the peak of the test stimulus.

Phase 2:

“Phase 2 of Experiment 2 determined the TBR for the 31-ms pulse with the elaborated synchrony judgment paradigm.” [718A]

Results:

Ex2 indicates match times. Results are shown in figure 4, which indicates the TBR for each subject.

General Discussion

Duration of Visible Persistence

Here the authors discuss “three fallacies in thinking of persistence as a concept that is adequately described by a single number, its duration.” [719A]

[skipping to]

Conclusion:

The elaborated synchrony judgment paradigm utilizes a highly refined form of introspection to trace out an entire temporal brightness response function to a test stimulus. The paradigm applies to a wide variety of possible temporal waveforms. For very brief test flashes, both the onset and the termination phases of the TBR differ widely across observers, with overall durations of the TBR varying from about 200 to about 500 ms.
[724B]

Weichselgartner, Erich, and George Sperling. "Continuous Measurement of Visible Persistence." Journal of Experimental Psychology 2.6 (1985): 711-725.

http://weichselgartner.de/erich/full_text/EW+GS_Visible_Persistence_JEP_1985.pdf

http://www.ncbi.nlm.nih.gov.sci-hub.org/pubmed/2934504

Also a reference to:

Levitt, H. "Transformed Up‐Down Methods in Psychoacoustics." The Journal of the Acoustical Society of America 49 (1971): 467-477.

http://bdml.stanford.edu/twiki/pub/Haptics/DetectionThreshold/psychoacoustics.pdf

http://scitation.aip.org/content/asa/journal/jasa/49/2B/10.1121/1.1912375

Levitt (1971) ‘Transformed up‐down methods in psychoacoustics’, notes

by Corry Shores
[Search Blog Here. Index-tags are found on the bottom of the left column.]

[Central Entry Directory]

[Neuro-Science, entry directory]

H. Levitt

Transformed up‐down methods in psychoacoustics

Brief summary:

The authors discuss methods for doing psychoacoustic experiments in which the subject’s responses determine the course of the experiment. For our purposes, we focused on the step-procedure. Here, a positive response means reducing the stimuli by a step, and a negative response means stepping the stimuli up. Then, it seems a middle point can be determined mathematically. [In the case of Weichselgartner & Sperling (1985), the subject needs to indicate when the brightness of a steady stimuli matches with a stimuli whose brightness is varying. If the subject just pushes a button, there is the problem of response times and variations they might introduce (one time being quicker, another especially slow). So instead, after the stimuli finish, the subject says whether the click comes before or after the perceived match in visual stimuli. If says comes after, then move the click back a step. If before, then move forward. Then, with all this data, it is then calculated when in fact they do perceive it as matching, the X₅₀ value of the psychometric curve.]

Notes:

 

Introduction

A. Adaptive Procedures in Psychophysics

An adaptive procedure is one in which the stimulus level on any one trial is determined by the preceding stimuli and response. [467]

Up-down methods are a type of sequential experiment, which is one where the course of the experiment is determined by experimental data. There are two types: (a) ones where the number of observations is determined by the data and (b) ones where the choice of stimulus levels is determined by the data. [467A]

B. The Psychometric Function

Look at fig 1a. The abscissa is the stimulus level. The ordinate is the proportion of ‘positive’ responses. A positive response might for example be the report from the subject that ‘the signal is present’.

[Please see the article to obtain a correct interpretation of its contents. For our purposes, I think we can derive what we need from figure 4 below. It seems if the response is positive, then the next trial takes the stimulus down a step. If the response is negative, then it steps up. Perhaps over time this approximates where the match would be. In the case of the Weichselgartner & Sperling (1985) experiment, this would mean that they use this step procedure to estimate when the subject senses the match between the steady reference stimuli and the varying test stimuli. The problem with having the subject just press the button when they sense the match could be the response time and the inaccuracies and variances it can introduce. But in this step method, the subjects chose the option (‘before,’ ‘after’) after the stimuli are all done. So there is not a response delay involved. ]

Levitt, H. "Transformed Up‐Down Methods in Psychoacoustics." The Journal of the Acoustical Society of America 49 (1971): 467-477.

http://bdml.stanford.edu/twiki/pub/Haptics/DetectionThreshold/psychoacoustics.pdf

http://scitation.aip.org/content/asa/journal/jasa/49/2B/10.1121/1.1912375

Sperling (1967) ‘Successive approximations to a model for short term memory’, notes

by Corry Shores
[Search Blog Here. Index-tags are found on the bottom of the left column.]

[Central Entry Directory]

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[The following is summary and quotation except for my bracketed commentary. All underlining and boldface are mine.]

George Sperling

‘Successive approximations to a model for short term memory’

Brief Summary:

By working through possible models for testing visual sensory memory, we learn that a sensory stimulus with information persists in our awareness even after it physically disappears. We read (‘scan’) parts of that image, and store them temporarily by repeating them vocally or subvocally (‘rehearsal’). But the parts that were never scanned disappear from awareness and seem to be lost forever to consciousness. [Whether or not they are registered subconsciously or unconsciousness would be another matter.]

Abstract [quoting]:

Experimental data are considered from a simple task in which an observer looks at letters and then writes them down. Three models are proposed. Model 1 consists of only two components: a visual memory for the letters and a motor translation component to enable copying a visual memory onto paper. Model 1 is inadequate because the visual image is shown not to persist until the time of reproduction. Model 2 corrects this deficiency by incorporating the possibility of subvocal rehearsal of the stimulus letters and an auditory memory for the rehearsal. However, Model 2 cannot account for performance with extremely short duration images because of the limit on the maximum rehearsal rate. The critical improvement in Model 3 is a more detailed specification of scanning, recognition and rehearsal, including a form of memory which is inherent in the process of recognition itself. Model 3 accounts for these data and incidently gives rise to some interesting inferences about the nature of consciousness. [285]

Summary

1. Introduction

Sperling proposes some simple memory tasks involving seeing random letters and writing them down from memory. On the basis of these simple methods, more complex ones might be derived.

2. Models

2.1 Model 1

The subject briefly sees a series of letters, and then from memory must immediately transcribe them from what they see in their ‘mind’s eye’. “While the subject is writing, the contents of his visual memory  are decaying, so that when he finally comes to write the fifth or sixth letter his visual memory of the stimulus no longer is legible.” [286]

The problem with this model is that just as soon as the subject begins writing the letters, the persisting image has already faded away.

2.2 Model 2

In various such experiments, Sperling recorded the voice of the subject, and found that often they speak the letters while writing. If the delay before reporting is extended to about 20 seconds or so, often times the subject will repeat the series and then when time comes to report them, speaks the letters while writing them. This could be a memory mechanism which refreshes the fading image.

Occasionally a subject, when he is writing down letters, can be heard to mumble the letters as he is writing them. His tendency to say the letters aloud can be emphasized by playing loud noise into his ears. Noise itself not seem to alter performance in any other significant way. We have this technique, together with a microphone placed near the subject’s mouth, to record the actual letters the subject is saying. We also recorded automatically whenever the subject was writing. The most interesting results with this technique are obtained when the subject is required to wait (e.g., | for 20 sec) after the stimulus exposure before writing the letters. He repeats (rehearses) the entire letter sequence several times with a pause between each repetition during the interval. Then, at the time of writing each letter, he also may speak it simultaneously.

Rehearsal suggests an obvious memory mechanism. The subject says a letter, hears himself saying it, and then remembers the auditory image. As the auditory image fades, he repeats it to refresh it. Most of our subjects do not vocalize during recall, but they all concur in stating that they rehearse subvocally. Therefore, we assume that the sound-image of a letter lean enter auditory memory directly from subvocal rehearsal without the necessity of actually being converted into sound and passing into the external world. These relations are illustrated in fig. 2.
[286|287]

According to Model 2, stimulus letters first are retained in visual storage. They are rehearsed, one at a time (i.e., converted from a visual to an auditory form), and then remembered in auditory storage. Subsequently they may be rehearsed again and again as required until they are written down. The limits on performance may arise either from the limited duration visual storage (so that some letters decay before they can be rehearsed) or from the limited capacity of the rehearsal-auditory storage loop, depending on the stimulating conditions. [288]

The problem with this method is the following. [Someone can recollect three letters from a retained image (having been given or lasting in the mind) for 0.1 sec. This means that in order to have pulled those letters out by reading them (vocally or subvocally), they had to do so at a speed of 30 letters a second.]

Attractive as Model 2 seems, it is inadequate for the following reason: it is possible to generate an image in visual storage which has a duration of definitely less than .1 sec and from which 3 letters can be reported. This would require a rehearsal rate of over 30 letters per second, which clearly is completely beyond the capabilities of the rehearsal processes described for Model 2.  [288]

2.3 Short duration visual images

[When testing recollection after many letters, the subject may only store four or five items in their memory. But it is also possible that the image of more of these items was there, but faded before they could report them. The solution to this is partial reporting. The idea is that the subject does not know until after which portion of the whole array they need to report. In

Sperling 1960, for example, there were grid arrays of letters, and subjects were asked after a flash of them to report on just one row. The idea here seems to be that if they can remember 4 or 5 items from one row, which was requested after the image faded, then they must have remembered that many in each of the other rows. For, were any of those other rows requested instead, they would have likewise reported just as many items. That would mean, that if a subject could recall all of one row a second or so after the image disappeared, then probably the whole image remained in sensory memory for that amount of time.] Partial reporting has shown that for a visual image of 18 letters given at 1/20 of a second, up to 10 items remain for as long as 2 seconds after the exposure.

There were also ‘letter-noise’ stimulus sequences, where visual noise was given after the stimulus. Then, by using clicks, the subject subjectively determined the onset of the visual image with its disappearance. This experiment found that

The apparent image duration of the letters in a letter-noise sequence is zero for extremely brief exposures (e.g., less than 10 msec) and then increases linearly with increasing exposure duration for durations exceeding about 20 msec.
[290a]

The results also showed that each subject had a particular order where they were most correct. In one case it was left-to-right, but more scrambled in others. However, the fact that all positions are reported better than chance indicates that the retentional images are not placed in the mind serially but rather in parallel [and then only afterward ‘read’ in some idiosyncratic order. Please see the first full paragraph on p.290 to be sure this is a correct interpretation.] [290]

Here is quotation for the above summarized parts:

In a letter-noise stimulus sequence, a second, interfering, stimulus (visual 'noise') is exposed immediately on termination of the letter stimulus. The duration of the letter images can be estimated by comparing them to an | auditory signal. Two different methods were used. In the first method two clicks were produced at the ears of the subject. He then adjusted the interval between the clicks until the auditory interval was judged equal to the visual duration. In the second method, the subject heard only one click at a time. We adjusted this click to occur so that it coincided subjectively with the onset of the visual image. After this judgment was complete, he made | another adjustment of the click to coincide with the termination of the visual image. The measured interval between clicks – taken to be the duration of the visual image – was the same by both methods. The apparent image duration of the letters in a letter-noise sequence is zero for extremely brief exposures (e.g., less than 10 msec) and then increases linearly with increasing exposure duration for durations exceeding about 20 msec (fig. 3a).

When stimuli of 5 letters, followed by noise, are exposed for various durations, the accuracy of report increases with exposure duration as shown in fig. 3b. The most interesting aspect of these data is revealed by analyzing separately the accuracy of report at each of the 5 locations (fig. 3c). The accuracy of report at each location reported increases continuously as a function of exposure duration. For this subject, the order of the successive locations which are reported correctly is generally left-to-right (I to V), except that location V is reported correctly at shorter exposures than location IV. Other subjects have different idiosyncratic orders, e.g., I, V, III, II, IV. By definition, in a purely serial process the nth location is not reported better than chance until the exposure duration at which the n-1th location is reported with maximum accuracy is exceeded. The observation that all locations begin to be reported at better than chance levels even at the briefest exposures, may be interpreted as evidence of an essentially parallel process for letter-recognition. This process gives the illusion of being serial because the different locations mature at different rates (cf. GLEZER and NEVSKAIA, 1964; SPERLING 1963). These findings are taken into account in Model 3 (fig 4).

2.4 Model 3

Model three has a scan-rehearsal component like Model 2.
But this part is subdivided into three other components. The first is the scan component. It “determines – within a limited range – the sequence of locations from which information is entered into subsequent components.” [291] [It seems the scan is reading from the persisting sensory image, and then the order of that scan is carried over into the rehearsal.]

The second different sub component is “recognition buffer-memory,” which “ converts the visual image of a letter provided by the scanner into a ‘program of motor-instructions’, and stores these instructions.” [191] And this program is then executed by the rehearsal component. [So the ordering of the scan is then carried into a program for repeating that order.]  What is important is that creating this program can be carried out in relatively short time (about 50 msec for 3 letters, for example) compared to the time it will take to execute that program of rehearsal (500 msec for 3 letters, for example.) [290]

The third new sub-component then is the rehearsal, in which the visual information is now stored in auditory cycles governed by motor-instructions. This then translates back to the visual image when reporting the letters on paper. [290]

3. Consciousness in the Memory Models

We can infer that there is an act of consciousness involved in the scan component of the process. Contents of visual memory which are not scanned fade away. But also, parts that were never scanned we never conscious. This is strange because it means neither subjectively nor objectively can these unscanned elements be observed.

Sperling, G. "Successive approximations to a model for short term memory." Acta psychologica 27 (1967): 285-292.

http://psych.stanford.edu/~jlm/pdfs/Sperling67.pdf

http://www.ncbi.nlm.nih.gov.sci-hub.org/pubmed/6062221

Sperling (1960) ‘The Information Available in Brief Visual Presentation’, notes

by Corry Shores
[Search Blog Here. Index-tags are found on the bottom of the left column.]

[Central Entry Directory]

[Neuro-Science, entry directory]

George Sperling

‘The Information Available in Brief Visual Presentations’

Brief Summary:

One way to know how long images stay in our mind after they disappear is to have people see a flash of objects then recall them after the image disappears. If they try to recall as many as possible regardless of position or type, then it is a whole report. One theory is that the image persists in the mind after the stimulus physically disappears, and when reporting, we select from the whole group, but that selection is arbitrary for the most part. One problem with the whole report method is that it alone does not tell us if the unselected parts persisted or not. If the whole image remains to our awareness, then this would be a persistence of the image, and if not, then either it does not persist or it does only partially. To find out which possibilities is true, Sperling employs a ‘partial report’ method. Here, the subject is to remember only a part of the set of flashed objects, but which part they might not know until shortly after the image has disappeared. If it can be shown that it does not matter from which part they are to report on, that suggests all of it remains in their mind’s eye, and they select from the whole. The partial report experiments here described show that not only does it not matter which part, and thus that the image probably persists, but also that subjects do better when they only need to recall part. One explanation for this again supports the image persistence theory: in whole reports, the subject must consume time deciding which figures to report, but in partial reports, that selection is made for them, giving them more time to make reports while the image persists in their minds.

Summary notes:

We often remember less than we original saw.

So we see a lot, but we can only remember part of it. [In the following, it seems our concern is not just with the quantity of content recalled in immediate sensory memory, but also with the duration of it. After the visual impression fades, it might become encoded as memory in a form which is not the sustained visual impression that remains in our vision. So we do not what to ask the subject to recall more than memory allows them too. They only need to report a portion of what they saw, and the question is, for how long does the impression stay in their minds so that they can still look at in it in their minds and withdraw information from it.?]

In order to circumvent the memory limitation in determining the information that becomes available following a brief exposure, it is obvious that the observer must not be required to give a report which exceeds his memory span. If the number of letters in the stimulus exceeds his memory span, then he cannot give a whole report of all the letters. Therefore, the observer must be required to give only a partial report of the stimulus contents. Partial reporting of available information is, of course, just what is required by ordinary schoolroom examinations and by other methods of sampling .available information.
[p.1]

After the stimulus terminates, the subject can be instructed to recall a certain part of the stimulus.

The experiments described in the following were conducted “to study quantitatively the information that becomes available to an observer following a brief exposure.” [2]

Letters were arranged in following sorts.

The stimulus array was flashed for 50 msec [see p.3]. Subjects were to report what they saw [depending on instruction for whole or partial reporting]. They were scored both for number correct and positions correct. [p.4]

Experiment 1: Immediate memory

Sperling writes:

When an S is required to give a complete (whole) report of all the letters on a briefly exposed stimulus, he will generally not re- | port all the letters correctly. The average number of letters which he does report correctly is usually called his immediate memory span or span of apprehension for that particular stimulus material under the stated observation conditions. An expression such as immediate-memory span ( Miller, 1956a) implies that the number of items reported by S remains invariant with changes in stimulating conditions. [p.4-5]

All 12 types of arrays [‘of stimulus materials’] were used.

Results:

the average number of correct letters contained in an S's whole report of the stimulus is approximately | equal to the smaller of (a) the number of letters in the stimulus or (b) a numerical constant-the span of immediate-memory which is different for each S. The use of the term immediate-memory span is therefore justified within the range of materials studied.
[5-6]

Experiment 1 showed that, regardless of material, Ss could not report more than an average of about 4.5 items per stimulus exposure.
[p6]

Experiment 2: Exposure duration

In the previous experiment, the exposure duration to the stimulus was short, 0.05s. In order to determine whether the 4.5 item limitation results from the shortness of the duration, we need to vary that duration.

Procedure:

Subjects were given tasks from prior experiment, except at varying durations of exposure to the stimulus: 0.015, 0.050, 0.150, 0.200, and 0.5oo second durations.

Results:

The main result is that exposure duration, even over a wide range, is not an important parameter in · determining the number of letters an S can recall correctly. Both individually and as a group, Ss show no systematic changes in the number of letters correctly reported as the exposure duration was varied from 0.015 to 0.500 sec. The invariance of the number of letters reported as a function of exposure durations up to about 0.25 sec. for the kind of presentation used ( dark pre- and postexposure fields) has long been known ( Schumann, 1904) .
[p6]

Experiment 3: Partial Report

[The controls experiments above tell us the full total quantity of the amount of information available to immediate recollection. This experiment will determine if the subject has more information than she can indicate in the immediate memory report. What this would suggest is that in the full reports, the subjects could have recalled different parts of the arrays, because all of it is available, but it decays, and the subject needs to report as much as possible, choosing arbitrarily from the retained image. If the subjects are able to recall the same number of figures but at varying spatial locations, then this suggests there is such a retained image from which a partial report can be selected.]

Experiments 1 and 2 have demonstrated the span of immediate-memory as an invariant characteristic of each S. In Experiment 3 the principles of testing in a perceptual situation that were advanced in the introduction are applied in order to determine whether S has more information available than he can indicate in his limited immediate-memory report.

The S is presented with the stimulus as before, but he is required only to make a partial report. The length of this report is four letters or less, so as to lie within S's immediate-memory span. The instruction that indicates which row of the stimulus is to be reported is coded in the form of a tone. The instruction tone is given after the visual presentation. The S does not know until he hears the tone which row is called for. This is therefore a procedure which samples the information that S has available after the termination of the visual stimulus.
[p.6]

Procedure:

Arrays with only two lines were used. Right after they disappear, the subject heard either a high or low tone, indicating whether to report the upper or lower row. [It then seems cards with more rows were shown and cued with  more tones. see p.6Bd]

Results:

The subjects improved, at first averaging 4.5 and later 5.6 letters [compare to the 4.5 limit of the control whole report sessions.] The diagram below shows in fact that partial reporting yields higher recollection [the lower curve is average number of figures recalled in whole reporting, the middle in partial reporting. Perhaps it is for this reason. In both cases, the image decays rapidly. In whole reporting, it might take more time to decide where in the retained image to select the figures to report. But in partial reporting, those briefly time-consuming choices are made already for the subject, allowing for them to draw out more information in the short time that the image remains in their vision.]

In Fig. 3 the number of letters available as a function of the number of letters in the stimulus are graphed as the upper curves. For all stimuli and for all Ss, the available information calculated from the partial report is greater than that contained in the immediate-memory report. Moreover, from the divergence of the two curves it seems certain that, if still more complex stimuli were available, the amount of available information would continue to increase. [p.6]

Experiment 4: Decay of Available Information

Part 1: Development of Strategies of Observing

We will now explore the decay of available information by delaying the cue telling which parts to recall. They used these variations on the cue time (even placing it before and during the stimulus): “0.05 sec. before stimulus onset (-0.10 sec.), ±0.0-, +0.15-, +0.30-, +0.50-, + 1.0-sec. delays after stimulus off-go”. [p.8]

Each subject went through all of these variations in delay, going either in ascending or descending order.

Results:

Look first in fig.5 to the leftmost panel (5a). These are the results of one subject giving partial reports at varying delay times. (Arrows tell what order the sequence went in on a whole, thus here began with ascending). We see that the lines go down, indicating that there is a decay, and much of the visual information is lost after 0.25s. The second session (5b) began with descending, and the results were not so orderly. The third session (5c) had more trials and also had a part where the the cue came before the stimulus.

The variability of 5b may have resulted from the subject choosing a strategy where she first guesses which row will be requested, and is sometimes right and sometimes wrong. Another subject described changing strategies after 0.15s  from trying to remember all equally and guessing the row, and his diagram [see p.9]

Part 2: Final Level of Performance

The experimenters attempted to eliminate this factor of choosing a strategy of guessing the row. Three proposed ways are: increasing the number of figures, making selection less useful; have tones come slightly before the stimulus; have the experimenter say something that would change the subject’s approach to the experiment, for example “not testing memory but reading, don’t read the card until hear the tone”. [It is not clear to me if the following results come from an experiment implementing some or all or none of these, but it seems at least some. Given that the results show a variation of times, it is not clear that the second modification was used any differently than before.]

Results:

The data indicate that, for all Ss, the period of about one sec. is a critical one for the presentation of the instruction to report. If Ss receive the instruction 0.05 sec. before the exposure, then they give accurate reports : 9 1 % and 82% of the letters given in the report are correct for the 9- and 12-letter materials, respectively. These partial reports may be interpreted to indicate that the Ss have, on the average, 8.2 of 9 and 9.8 of 12 letters available. However, i f the instruction is delayed until one sec. after the exposure, then the accuracy of the report drops 32% (to 69% ) for the 9-letter stimuli, and 44% ( to 38%) for the 12-letter stimuli. This substantial decline in accuracy brings the number of | letters available very near to the number of letters that Ss give in immediate-memory ( whole) reports. [p.11-12]

[Experiment 5, skipped. It experiments with different pre- and post-exposure fields.]

Experiment 6: Letters and Numbers

[It could be that what is being remembered is a result of remembering locations. The following experiment reduces the importance of location.]

Procedure:

Subjects saw arrays mixed with both letters and numbers, and afterward were asked to recall only one or the other. [It seems this experiment also had trials asking for top and bottom rows too, regardless of symbol/number. see page 14Ad]

The results show that reporting either letters or numbers only is little better than immediate memory. [But it is better with locations. So asking for locations is a better method for finding how long images stay in our minds. Presumably there is not an unwanted advantage with positions, because in both cases the cue can come after the fact (and not be from guessing location ahead of time, see experiment 4). So presumably whether the subject is asked for types or for locations, in both cases, the image would have been equally available to their sensory memory.]

The failure in Experiment 6 to detect a substantial difference in accuracy between partial reports of only letters (or only numbers) and whole reports clearly illustrates that partial reports by position are more effective for studying the capacity of short-term information storage than partial reports by category.
[p.16]

[Experiment 7: Order of Report, skipped. From the results: “The results obtained in this experiment support the conclusions that both a position preference and the order of report ordinarily correlate with the accuracy of response, but that probably neither are necessary conditions for response accuracy.” p.19]

Discussion:

Sperling has two questions regarding why subjects remember more in partial reports than in whole reports.

(a) Why is the partial report more accurate than the whole report ? (b) Why does the partial report retain this added accuracy only for a fraction of a second after the exposure?
[20]

One way to answer [question b]  is with the subjective accounts of the subjects. They say that the image stays in their vision even when the tone sounds 150 msec after the image has physically disappeared.

The answers proposed are a systematic elaboration of an observation that is readily made by most viewers of the actual tachistoscopic presentation. They report that the stimulus field appears to be still readable at the time a tone is heard which follows the termination of the stimulus by 150 msec. In other words, the subjective image or sensation induced by the light flash outlasts the physical stimulus at least until the tone is heard. The stimulus information is thus "stored" for a fraction of a second as a persisting image of the objective stimulus. As the visual image fades, its legibility (information content) decreases, and consequently the accuracy of reports based upon it decreases. [p20AB]

Sperling then notes that sensation is not instantaneous. So the fact that the subject still sees the image after its extinction partly results from the fact that it takes time for the sensation to register in the subject’s awareness. But this is not necessarily related to the persistence of the image. It only refers to the delay. So what matters is not the delay after the extinction of the stimulus but rather the duration it remains before decaying.

There is other evidence, besides such phenomenological accounts, that suggests that information is available in the form of an image for a short time after extinction of the physical stimulus. In the first place, it is inconceivable that the observers should stop seeing the stimulus at exactly the moment the light is turned off. The rise and fall of sensation may be rapid, but they are not instantaneous. The question is not whether the observer continues to see the stimulus after the illumination is turned off, but for how long he continues to see the stimulus.
[p. 20]

Sperling then cites other research which would estimate the persistence of vision to be from 0.05 to 1.0 sec, and most probably around 1/6 of a sec.

These estimates of the persistence of the visual sensation vary from a minimum of 0.05 sec. (Wundt, 1899) to almost one sec. (McDougall, 1904). The most representative estimates are in the neighborhood of l /6 sec. (cf. Pieron, 1934), a figure that is in good agreement with the results.¹³ [ft 13: Measurements of the persistence of sensation have almost invariably used techniques which have at most questionable validity. Wundt's method depends upon masking, the effect of the persisting stimulus upon another stimulus. The masking power of a stimulus may be quite different from its visibility. McDougall's measurements, as well as those cited by Pieron, depend upon motion of a stimulus across the retina. Such measurements are undoubtedly influenced by the strong temporal and spatial interactions of the eye (Alpern, 1953). Schumann's ingenious application of the method of Baxt to the determination of persistence is probably the only experiment that utilizes pattern stimulation. The other methods have not been tried with pattern stimuli although there .is, a priori, no good reason why they have not been. The possibility that the persistence of pattern information is quite different from persistence of "brightness" has not been investigated.] [Citing these sources: Wundt, W. An introduction to psychology. London: Allen & Unwin, 1925 (reprinted.) Transl. from 2nd German ed, by R Pinter. Edinburgh, Ballentyre Press, 1912. ((see pdf, where much of the bib info is overwritten by hand.)). McDougall, W. The sensations excited by a single momentary stimulation of the eye. Brit. J. Psychol., 1904, 1, 78-113. Pieron, H. L'evanouissement de la sensation lumineuse: Persistance indifferenciable et persistance totale. Ann. psychol., 1934, 35, 1-49. Alpern, M. Metacontrast. J. Opt. Soc. Amer., 1953, 43, 648-657.]
[p.20]

Sperling again on the persistence of vision:

This then is the evidence-phenomenological reports, the effects of the postexposure fields, the known facts of the persistence of sensation, and the detailed characteristics of the responses-that is consistent with the hypothesis that.information is initially stored as a visual image and that the Ss can effectively utilize this information in their partial reports. In the present context, the term, visual image, is taken to mean that (a) the observer behaves as though the physical stimulus were still present when it is not (that is, after it has been removed ) and that (b) his behavior in the absence of the stimulus remains a function of the same variables of visual stimulation as it is in its presence, The units of a visual image so defined are always those of an equivalent "objective image," the physical stimulus. It is as logical or illogical to compute the information contained in a visual image (as was done in Experiments 3 and 4) as it is to compute the information in a visual stimulus.
[p.21]

But as indicated above, the subject behaves ‘as though’ it were present. Perhaps in fact it is not visibly present but only seems be in their behavior.

"Visual image" and "persistence of sensation" are terms suggested by the asynchrony between the time during which a stimulus is present and the time during which the observer behaves as though it were present. Although asynchrony is inevitable for short exposure durations, there is, of course, no need to use the term "visual image" in a description of this situation. One might, for example, refer simply to an "information storage" with the characteristics that were experimentally observed. This form of psychological isolationism does injustice to the vast amount of relevant researches.
[p.22]

Persistence of Vision and Afterimages

[It would seem the difference so far used with the terminology is this: persistence of vision is the very immediate lingering impression, and the afterimage remains shortly after, less than longer-term memory.]

Between the short persistence of vision and the remembrance of a long-passed event, there is an intermediate situation, the afterimage, which requires consideration. In discussing afterimages, it will be useful to distinguish some phases of vision that normally follow an intense or prolonged stimulus. First, there is the "initial" (or primary, or original) "image" (or sensation, or impression, or perception, or response). Any combination of a term from the first and from the second of these groups may be used. The initial image is followed by a latent period during which nothing is seen and which may in turn be followed by a complex sequence of afterimages.
[p.22]

George Sperling. The information available in brief visual presentations. Psychological monographs: General and applied, Vol. 74, No. 11. (1960), pp. 1-29.

http://www.citeulike.org/group/1696/article/995840

http://aris.ss.uci.edu/HIPLab/staff/sperling/PDFs/Sperling_PsychMonogr_1960.pdf