Temporal structure of letter groups and span of perception

The span of perception for letter groups depends on number of letters presented, length of presentation and structure of the groups. The experiment reported varied the temporal structure of the groups, leaving the total number of letters constant. Groups of 12 letters were presented as a whole or in two or more successive “units.” The total time of presentation was 1-5 sec. In the first experiment each unit was visible until the next appeared, in the second experiment units were visible only during 1/4 sec., although intervals between successive units were kept constant.

The following conclusions emerged:

(a) The visual presence of units did not affect the reproduction for durations over 0.25 sec., except in the 12-letter presentations.

(b) 2×6 letters gave better results than either simultaneous presentation or other divisions; temporal separation was 0.75 sec.

(c) Higher order approximations to Dutch have more influence on 3 × 4, 2 × 6 and 1 × 12 letters than on 4 × 3 and 6 × 2 letters.

(d) A serial order effect exists: central units are reproduced less well than first and last units.

It is suggested that handling a fixed amount of information within a fixed period is limited on the one hand by confusion between simultaneous elements and on the other hand by the interaction between successive units presented too rapidly to allow for proper operation of immediate memory.

The difference between span of perception and span of memory is stressed.     

How fast small things become large: Dynamic change in judgment

Judgments are context bound. Moreover, in most situations, context is changing; hence judgments often reflect a dynamic adaptation to these changes. This study is on working memory load as a factor that potentially moderates speed of adaptation to new context. Two specific stimulus formats used in generalization tests, simultaneous vs successive presentation, were intended to reflect substantial differences in memory load. Conditions that place a higher memory load on the respondent (successive presentation) should show slower changing effects than do conditions that entail a lower memory load (simultaneous presentation). Sixty participants were trained in two stimulus two forced-choice visual discriminations of size. Later generalization tests included more extreme visual stimuli. The stimulus that was seen as neither “small” nor “large” (50% ratings each) changed in the direction of the central stimuli within the stimulus series, with both successive and simultaneous stimulus presentation (adaptation). Multilevel regression analyses showed that change increased gradually in successive stimulus presentation, whereas change was immediate in simultaneous presentation. A significant three-way interaction indicated that generalization was faster with simultaneous presentation of generalization test stimuli than with successive presentation. The results showed that the speed of Point of Subjective Indifference (PSI) shift depends on the mental representation of experience that is strongly related to working memory. The study therefore makes a contribution to the understanding the speed of behavioural change during transition, e.g., the transition from school to work. On a macro-level, model application may assist rapid learning and behavioural adaptation, for instance when individuals change from one cultural context to another.     

Like and cross modality responses in normal and subnormal children

Experiments which investigated response behaviour in imbeciles and normals, in a conflict situation between a general verbal instruction and direct stimuli, were carried out. It was found that combined verbal-motor responses did not give better results than either verbal or motor responses alone. Results in accordance with the general instruction were significantly better if the subnormal children responded in a different modality from the one in which the signals were given. While normals and imbeciles differed markedly in their ability to perform the tasks in like-modality trials, this difference was less apparent in cross modality responses.     

Attention, rehearsal, and memory for serial order

In three experiments, subjects attended to one of two simultaneous nine-digit sequences, presented binaurally in different voices (one male, one female). Substantial repetition effects (defined as gains in immediate memory performance for previously presented sequences relative to novel ones) were found for two exposure conditions: (a) one that required reproduction of the full sequence on each exposure (Experiment 1), and (b) one that required recall of a different two-digit subsequence on each exposure (Experiment 2). In Experiment 3, the following conditions produced no repetition effects, even though tests had substantial power to detect small effects: 10 consecutive presentations in the unattended voice; 4 prior presentations in a task that required attention to each digit as it was presented (but not to digit order); and 4 prior presentations in a task that required attention to digit order during their presentations. These results, together with those of previous studies, support the conclusion that repetition effects on immediate memory occur only with procedures that encourage covert rehearsal of full-sequence order on each exposure. These findings also limit the generality of others' conclusions that event order is automatically encoded for attended events, and extend previous findings showing unattended exposures to be without effect on recall measures.     

The effect of contrast upon perceived speed: a general phenomenon?

The perceived speed of a grating pattern has often been reported to slow as the contrast of the pattern is reduced (though there are some contradictory reports). The mechanism of this perceived slowing has not yet been established nor have the conditions under which the effect occurs (or does not occur). We have therefore examined a range of stimuli that differ upon such aspects as one versus two dimensions, periodic versus nonperiodic, and whether the stimuli occur within a static window. We have also examined a range of stimulus speeds, different types of motion, and simultaneous versus successive presentations. We have found evidence for contrast-induced changes in perceived speed in all our stimuli, and thus suggest that none of the stimulus factors listed above is critical in producing the effect. Though the pattern of results is complex and shows substantial intersubject variation, we generally found that slowly moving patterns presented simultaneously produced the greatest decrease in perceived speed with decreasing contrast. On the other hand faster speeds and successive presentation produced more veridical matches or even an increase in perceived speed with decreasing contrast.     

加工速度、工作记忆与数字推理能力的发展

本研究得出在数字推理能力的发展过程中加工速度和工作记忆发挥着重要的作用,其中工作记忆对数字推理能力的发展的作用大于加工速度。加工速度可能是年龄与工作记忆的中介,加工速度可能仅对工作记忆的发展起一种直接调节作用,工作记忆对数字推理能力的发展可能起直接调节作用,在数字推理能力的发展过程中工作记忆比加工速度可能发挥着更直接、更一般的作用。     

Discrimination of simultaneous and successive tones

A series of discrimination tasks involving simultaneous and successive presentation of pairs of piano notes was given to 27 Ss. The listeners exhibited less-than-perfect ability to “hear out” the component notes in simultaneous presentations. This finding, in agreement with the results of previous investigators, demonstrated the limitation of Ohm’s law of acoustical analysis. It was also found that changes in successive notes fOllowing simultaneous notes were discriminated more accurately than changes in simultaneous notes following successive notes. This was interpreted as suggesting that listeners are better able to analyze than to synthesize the components of complex tones.     

Locus and persistence of capacity limitations in visual information processing

Although there is considerable evidence that stimuli such as digits and letters are extensively processed in parallel and without capacity limitations, recent data suggest that only the features of stimuli are processed in parallel. In an attempt to reconcile this discrepancy, we used the simultaneous/successive detection paradigm with stimuli from experiments indicating parallel processing and with stimuli from experiments indicating that only features can be processed in parallel. In Experiment 1, large differences between simultaneous and successive presentations were obtained with an R target among P and Q distractors and among P and B distractors, but not with digit targets among letter distractors. As predicted by the feature integration theory of attention, false-alarm rates in the simultaneous condition were much higher than in the successive condition with the R/PQ stimuli. In Experiment 2, the possibility that attention is required for any difficult discrimination was ruled out as an explanation of the discrepancy between the digit/letter results and the R/PQ and R/PB results. Experiment 3A replicated the R/PQ and R/PB results of Experiment 1, and Experiment 3B extended these findings to a new set of stimuli. In Experiment 4, we found that large amounts of consistent practice did not generally eliminate capacity limitations. From this series of experiments we strongly conclude that the notion of capacity-free letter perception has limited generality.     

Variables influencing the mode of processing of complex stimuli

The present study attempts to specify some of the conditions under which parallel and serial processing may occur. The three variables studied were (1) type of task, (2) relative set for speed vs accuracy, and (3) practice. Pairs of multidimensional, geometric stimuli were presented either simultaneously or successively to S who was required to indicate whether they were the same or different. Each S participated in nine sessions. For half of the Ss speed was emphasized, and for the other half accuracy was emphasized. The results indicated that: (1) responses were faster with successive presentation than with simultaneous presentation; (2) with successive presentation, processing was serial; (3) in the simultaneous presentation condition, a gradual shift from serial to parallel processing occurred with practice; and (4) the speed and accuracy instructions used in this experiment produced no differential effects on latency or errors.     

Single, but not multiple pairings of sucrose and corticosterone enhance memory for sucrose drinking and amplify remote reward relativity effects

This study tested whether pre-training pairings of ingestion of a 32% sucrose solution and injection(s) of corticosterone (B) would enhance later ingestion in the absence of B, and whether these effects would carry over into later contrast-like effects when animals were subsequently shifted to 4% sucrose. Frequency-dependence of these pairings was also examined. Three groups of male Sprague-Dawley rats were adrenalectomized (ADX). A fourth group was sham ADX. Each ADX group received three presentations of sucrose and B (666 microg/kg, s.c.). One received unpaired presentations (separated by days), one received two unpaired presentations and one paired (i.e., simultaneous) presentation, and one received three paired presentations. Shams received three sucrose presentations paired with saline. Single, but not multiple pairings of B with ingestion of a 32% sucrose solution enhanced later sucrose ingestion, a memorial-like effect that carried over into later, opposite contrast-like effects upon presentation of a less-preferred 4% sucrose solution. These effects could not be easily ascribed to differences in training, other than the pairing regimen itself, nor to motivational differences at the time of testing, and were presumed to be memorial. The pairing and frequency-dependence of these appetitive phenomena are analogous to what is frequently observed during acute or chronic exposure to aversive situations and/or neuromodulatory stress hormones, in terms of their bidirectional effects on memory. Through effects on memory, stress hormones may modulate reward and reward relativity.     

Memory enhancement for emotional words: Are emotional words more vividly remembered than neutral words?

Individuals are more likely to remember negative information than neutral information. In the experiments reported here, we examined whether individuals were also more likely to remember details of the presentation of negative words, as compared with neutral words. In Experiment 1, the remember-know procedure was used to examine the effect of emotion on the vividness of an individual's memory, showing that remember responses were more frequently assigned to negative words than neutral words. In Experiment 2, a source memory paradigm was used, and again, evidence that individuals' memories were more detailed for negative than for neutral words was found. In Experiments 3-6, we examined the relative contribution of valence and arousal, finding that both dimensions increased the vividness of remembered information (i.e., items with valence only and those that elicited arousal were better remembered than neutral information) but that the effect was greater for words that evoked arousal than for those with valence only. The results support a qualitative, as well as a quantitative, memory benefit for emotional, as compared with neutral, words.     

Stimulus control of information processing in pigeon short-term memory

Six pigeons were trained initially on a delayed successive matching-to-sample task using red and green fields as sample and test stimuli. Following acquisition, each sample was followed either by a vertical line (“remember” cue), which indicated that sample memory would be tested, or by a horizontal line (“forget” cue), which indicated that sample memory would not be tested. During the experiments, sample memory on forget trials was tested occasionally. A series of five experiments revealed: (a) better retention on remember trials than on forget trials, (b) increased effectiveness of a forget cue when it followed closely sample offset, (c) more rapid forgetting over a retention interval ranging from 3 to 6 sec on forget trials than on remember trials, (d) a “cancellation” effect in which a remember cue which followed immediately the offset of a forget cue attenuated markedly the effectiveness of the forget cue, and (e) an “insulation” effect in which the effectiveness of a forget cue was reduced considerably when presented after a remember cue. It was concluded that pigeons actively process or rehearse the sample memory during the retention interval.     

Presentation modality,rehearsal-prevention conditions,and auditory confusions in tests of short-term memory

Ss were presented four-letter sequences either auditorily or visually and asked for ordered recall after 0, 2.1, 4.2, 8.4, or 12.6 sec of digit categorization. Three different rehearsal-prevention conditions were required during presentation of the memory set: categorizing, suppressing (saying "dah"), or pronouncing each letter. Recall was worst after categorizing, best after pronouncing. Auditory presentation led to better recall after no delay but more rapid forgetting than visual presentation, regardless of the rehearsal-prevention condition. These results, and analyses of auditory confusions, are inconsistent with a view of memory which asserts that sensory information is encoded auditorily regardless of presentation modality or vocalization behavior during presentation.     

Memory encoding of stimulus features in human perceptual learning

Two experiments analysed memory encoding in human perceptual learning. Both experiments started with preexposure without feedback to four checkerboards composed by a unique feature each and sharing a common feature (AX, BX, CX, and DX). Elements of one pair were presented intermixed and elements of the other pair were presented in separate blocks. Immediately after preexposure participants completed a memory recognition task in which the characteristics of the distractors were manipulated. Experiment 1 showed that only intermixed presentation results in good encoding of the unique features of the stimuli. Experiment 2 demonstrated that intermixed preexposure results in different encoding of unique versus common features of the stimuli: Participants are able to remember A and B better than they remember X, whereas for the blocked condition memory for C, D, and X does not differ. Overall, the results presented here support the proposal that intermixing stimuli results in differential memory traces for unique versus common features and that this contributes to the intermixed/blocked effect.     

The effect of temporal delay and spatial differences on cross-modal object recognition

In a series of experiments, we investigated the matching of objects across visual and haptic modalities across different time delays and spatial dimensions. In all of the experiments, we used simple L-shaped figures as stimuli that varied in either the x or the y dimension or in both dimensions. In Experiment 1, we found that cross-modal matching performance decreased as a function of the time delay between the presentation of the objects. We found no difference in performance between the visual-haptic (VH) and haptic-visual (HV) conditions. Cross-modal performance was better when objects differed in both the x and y dimensions rather than in one dimension alone. In Experiment 2, we investigated the relative contribution of each modality to performance across different interstimulus delays. We found no differential effect of delay between the HH and VV conditions, although general performance was better for the VV condition than for the HH condition. Again, responses to xy changes were better than changes in the x or y dimensions alone. Finally, in Experiment 3, we examined performance in a matching task with simultaneous and successive presentation conditions. We failed to find any difference between simultaneous and successive presentation conditions. Our findings suggest that the short-term retention of object representations is similar in both the visual and haptic modalities. Moreover, these results suggest that recognition is best within a temporal window that includes simultaneous or rapidly successive presentation of stimuli across the modalities and is also best when objects are more discriminable from each other.     

Recognition in a visuospatial memory task: The effect of presentation

The influence of the mode of presentation (simultaneous vs. sequential) on accuracy and latency of visuospatial recognition was explored in three experiments. In Experiment 1, two groups were administered a visuospatial task in which a number of positions were shown either simultaneously or sequentially (in a random order); memory was tested using a recognition procedure of visuospatial patterns, either identical or different (a single cell displaced). The results showed that (1) performance was higher in the simultaneous than in the sequential presentation, and (2) decision time increased with complexity in the sequential presentation but not in the simultaneous presentation. In Experiment 2, the same task was used in three conditions of presentation, simultaneous, random sequential, and ordered sequential; at test, a single location, rather than a pattern, was presented for recognition. The results showed that (1) performance was higher in the simultaneous and in the ordered sequential presentations than in the random sequential one, and (2) decision time increased with complexity. In Experiment 3, the same task was used in the same three conditions of presentation, simultaneous, random sequential, and ordered sequential; at test either an identical or a “displaced” pattern was presented for recognition. The results showed that (1) performance was equivalent in the three types of presentation, and (2) decision time increased with complexity for “hit” items; different patterns of linear relations were observed for “correct rejections” items. The results are interpreted in terms of the organisation of visuospatial working memory, and three types of encoding—extrafigural spatial encoding, visual pattern encoding, and spatial path encoding—were proposed.     

Memory while shadowing

Subjects were asked to repeat verbally (shadow) English words which were presented to one ear. They were then tested for their memory of two-digit numbers which were presented to their other ear. It is demonstrated that subjects have no memory for these digits if they must continue to shadow for 20 sec. before being tested on their memory for the digits. However, if tested immediately after the digit presentation, they do remember some digits. Hence, verbal material presented on non-attended channels gets into a short-term memory, but is not transferred into long-term memory.     

Memory skills mediating superior memory in a world-class memorist

Laboratory studies have investigated how individuals with normal memory spans attained digit spans over 80 digits after hundreds of hours of practice. Experimental analyses of their memory skills suggested that their attained memory spans were constrained by the encoding time, for the time needed will increase if the length of digit sequences to be memorised becomes longer. These constraints seemed to be violated by a world-class memorist, Feng Wang (FW), who won the World Memory Championship by recalling 300 digits presented at 1 digit/s. In several studies we examined FW’s memory skills underlying his exceptional performance. First FW reproduced his superior memory span of 200 digits under laboratory condition, and we obtained his retrospective reports describing his encoding/retrieval processes (Experiment 1). Further experiments used self-paced memorisation to identify temporal characteristics of encoding of digits in 4-digit clusters (Experiment 2), and explored memory encoding at presentation speeds much faster than 1 digit/s (Experiment 3). FW’s superiority over previous digit span experts is explained by his acquisition of well-known mnemonic techniques and his training that focused on rapid memorisation. His memory performance supports the feasibility of acquiring memory skills for improved working memory based on storage in long-term memory.     

Auditory versus visual processing of three sets of simultaneous digit pairs.

Two experiments were conducted to determine whether the auditory and visual systems process simultaneously presented pairs of alphanumeric information differently. In Experiment 1, different groups of subjects were given extensive practice recalling pairs of superimposed visual or auditory digits in simultaneous order (the order of arrival) or successive order (one member of each digit pair in turn, followed by the other pair member). For auditory input, successive order of recall was more accurate, particularly for the last two of three pairs presented, whereas for visual input, simultaneous order of recall was more accurate. In Experiment 2, subjects were cued to recall in one or the other order either immediately before or after stimulus input. Recall order results were the same as for Experiment 1, and precuing did not facilitate recall in either order for both modalities. These results suggest that processing in the auditory system can only occur successively across time, whereas as in the visual system processing can only occur simultaneously in space.