Interitem Intervals Research Articles

Temporal crowding is a unique phenomenon reflecting impaired target encoding over large temporal intervals.

Crowding refers to impaired object identification when presented with other objects, and it is well established that spatial crowding-crowding from adjacent objects-affects many aspects of visual perception and cognition. A similar interference also occurs across time-the identification of a target object is impaired when distracting objects precede and succeed it. When such interference is observed with relatively long interitem intervals it is termed temporal crowding. Thus far, little was known about temporal crowding and its underlying processes. Particularly it was unknown which aspects of visual processing are impaired by temporal crowding, and the answer to this question bears critical theoretical implications. To reveal the nature of this impairment we used a continuous-report task and a mixture-model analysis. In three experiments, observers viewed sequences of three oriented items separated by relatively long intervals (170-475ms). The target was the second item in the sequence, and the task was to reproduce its orientation. The findings suggest that temporal crowding impairs target encoding and increases substitution errors, but there was no evidence of a reduced signal-to-noise ratio. This pattern of results was similar regardless of stimuli duration and target-distractor similarity. However, it differed considerably from the pattern found for ordinary masking and spatial crowding, indicating that temporal crowding is a unique phenomenon. Moreover, the finding that temporal crowding affected the precision of target encoding even when the items were separated by almost half a second suggests that visual processing requires a surprisingly long time to complete.

What do people typically do between list items? The nature of attention-based mnemonic activities depends on task context.

It is commonly assumed that attention-demanding postencoding processes take place during the free time immediately following encoding of each memory item in a list. These processes are thought to prevent loss of information from working memory (WM). We tested whether interitem pauses during presentation of a list are used to focus attention (a) on the last-presented memory item or (b) on all items currently in WM, and (c) whether this changes over time. Here, we presented black probe letters between to-be-remembered red letters. Participants judged whether each probe letter corresponded to the last-presented memory item (last-item match group) or to any of the memory items presented up to that point in the list (any-item match group). To examine mnemonic processing as a function of time, the delay between the to-be-remembered letter and the following probe was manipulated in three experiments. When preprobe delays and interitem intervals were relatively short (Experiment 1), recall performance was observed to be better in the last-item match group and this did not change as a function of the duration of the delay before the probe. When preprobe delays and interitem intervals were longer however (Experiment 2), this disruptive effect of Any-item match instructions was no longer observed. This pattern was found again in Experiment 3 and suggests that the nature of the attention-demanding postencoding processes taking place in between memory items depends on task context in a systematic manner. The results are discussed in terms of previously proposed attention-demanding processes; specifically, consolidation and refreshing. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Individual differences in visuospatial working memory: benefits from environmental support for rehearsal

ABSTRACTPrevious research has suggested that participants with low working memory spans are less likely than those with high spans to engage in rehearsal and other effective strategies during memory tasks. However, most of this research has been conducted in the verbal domain, and less is known about strategy differences in visuospatial working memory. Therefore, the present experiments investigated potential individual differences in the benefit participants receive from environmental support for visuospatial rehearsal. In Experiment 1, memory spans were significantly larger when support was present (i.e. when the array of possible locations remained on the screen) during long inter-item intervals, but importantly, the observed benefit was larger for high-span participants than low-span participants, suggesting that high spans were more likely to use support to facilitate their rehearsal. Other research has suggested that low spans may benefit more than high spans from rehearsal instructions, and so in Experiment 2, participants also were provided with such instructions. However, the rehearsal instructions did not improve memory spans significantly in either group, suggesting that low spans are not only naturally less strategic than high spans, but they may be less capable of taking advantage of effective rehearsal strategies, even when environmental support is present.

Serial recall of colors: Two models of memory for serial order applied to continuous visual stimuli.

This study investigated the effects of serial position and temporal distinctiveness on serial recall of simple visual stimuli. Participants observed lists of five colors presented at varying, unpredictably ordered interitem intervals, and their task was to reproduce the colors in their order of presentation by selecting colors on a continuous-response scale. To control for the possibility of verbal labeling, articulatory suppression was required in one of two experimental sessions. The predictions were derived through simulation from two computational models of serial recall: SIMPLE represents the class of temporal-distinctiveness models, whereas SOB-CS represents event-based models. According to temporal-distinctiveness models, items that are temporally isolated within a list are recalled more accurately than items that are temporally crowded. In contrast, event-based models assume that the time intervals between items do not affect recall performance per se, although free time following an item can improve memory for that item because of extended time for the encoding. The experimental and the simulated data were fit to an interference measurement model to measure the tendency to confuse items with other items nearby on the list-the locality constraint-in people as well as in the models. The continuous-reproduction performance showed a pronounced primacy effect with no recency, as well as some evidence for transpositions obeying the locality constraint. Though not entirely conclusive, this evidence favors event-based models over a role for temporal distinctiveness. There was also a strong detrimental effect of articulatory suppression, suggesting that verbal codes can be used to support serial-order memory of simple visual stimuli.

Time manages interference in visual short-term memory

ABSTRACTEmerging evidence suggests that age-related declines in memory may reflect a failure in pattern separation, a process that is believed to reduce the encoding overlap between similar stimulus representations during memory encoding. Indeed, behavioural pattern separation may be indexed by a visual continuous recognition task in which items are presented in sequence and observers report for each whether it is novel, previously viewed (old), or whether it shares features with a previously viewed item (similar). In comparison to young adults, older adults show a decreased pattern separation when the number of items between “old” and “similar” items is increased. Yet the mechanisms of forgetting underpinning this type of recognition task are yet to be explored in a cognitively homogenous group, with careful control over the parameters of the task, including elapsing time (a critical variable in models of forgetting). By extending the inter-item intervals, number of intervening items and overall decay interval, we observed in a young adult sample (N = 35, Mage = 19.56 years) that the critical factor governing performance was inter-item interval. We argue that tasks using behavioural continuous recognition to index pattern separation in immediate memory will benefit from generous inter-item spacing, offering protection from inter-item interference.

Effects of age and environmental support for rehearsal on visuospatial working memory.

The present study investigated whether older adults' visuospatial working memory shows effects of environmental support for rehearsal similar to those observed in young adults (Lilienthal, Hale, & Myerson, 2014). When the duration of interitem intervals was 4 s and participants had sufficient time to rehearse, location memory spans were larger in both age groups when environmental support was present than when support was absent. Critically, however, the age-related difference in memory was actually larger when support was provided, suggesting that young and older adults may differ in their rehearsal of to-be-remembered locations. (PsycINFO Database Record

The effects of environmental support and secondary tasks on visuospatial working memory.

In the present experiments, we examined the effects of environmental support on participants' ability to rehearse locations and the role of such support in the effects of secondary tasks on memory span. In Experiment 1, the duration of interitem intervals and the presence of environmental support for visuospatial rehearsal (i.e., the array of possible memory locations) during the interitem intervals were both manipulated across four tasks. When support was provided, memory spans increased as the interitem interval durations increased, consistent with the hypothesis that environmental support facilitates rehearsal. In contrast, when environmental support was not provided, spans decreased as the duration of the interitem intervals increased, consistent with the hypothesis that visuospatial memory representations decay when rehearsal is impeded. In Experiment 2, the ratio of interitem interval duration to intertrial interval duration was kept the same on all four tasks, in order to hold temporal distinctiveness constant, yet forgetting was still observed in the absence of environmental support, consistent with the decay hypothesis. In Experiment 3, the effects of impeding rehearsal were compared to the effects of verbal and visuospatial secondary processing tasks. Forgetting of locations was greater when presentation of to-be-remembered locations alternated with the performance of a secondary task than when rehearsal was impeded by the absence of environmental support. The greatest forgetting occurred when a secondary task required the processing visuospatial information, suggesting that in addition to decay, both domain-specific and domain-general effects contribute to forgetting on visuospatial working memory tasks.

Distinct roles for dorsal CA3 and CA1 in memory for sequential nonspatial events

Previous studies have suggested that dorsal hippocampal areas CA3 and CA1 are both involved in representing sequences of events that compose unique episodes. However, it is uncertain whether the contribution of CA3 is restricted to spatial information, and it is unclear whether CA1 encodes order per se or contributes by an active maintenance of memories of sequential events. Here, we developed a new behavioral task that examines memory for the order of sequential nonspatial events presented as trial-unique odor pairings. When the interval between odors within a studied pair was brief (3 sec), bilateral dorsal CA3 lesions severely disrupted memory for their order, whereas dorsal CA1 lesions did not affect performance. However, when the inter-item interval was extended to 10 sec, CA1 lesions, as well as CA3 lesions, severely disrupted performance. These findings suggest that the role of CA3 in sequence memory is not limited to spatial information, but rather appears to be a fundamental property of CA3 function. In contrast, CA1 becomes involved when memories for events must be held or sequenced over long intervals. Thus, CA3 and CA1 are both involved in memory for sequential nonspatial events that compose unique experiences, and these areas play different roles that are distinguished by the duration of time that must be bridged between key events.

AN EXPERIMENTAL ANALYSIS OF MEMORY PROCESSING

Rhesus monkeys were trained and tested in visual and auditory list-memory tasks with sequences of four travel pictures or four natural/environmental sounds followed by single test items. Acquisitions of the visual list-memory task are presented. Visual recency (last item) memory diminished with retention delay, and primacy (first item) memory strengthened. Capuchin monkeys, pigeons, and humans showed similar visual-memory changes. Rhesus learned an auditory memory task and showed octave generalization for some lists of notes--tonal, but not atonal, musical passages. In contrast with visual list memory, auditory primacy memory diminished with delay and auditory recency memory strengthened. Manipulations of interitem intervals, list length, and item presentation frequency revealed proactive and retroactive inhibition among items of individual auditory lists. Repeating visual items from prior lists produced interference (on nonmatching tests) revealing how far back memory extended. The possibility of using the interference function to separate familiarity vs. recollective memory processing is discussed.

Distinctiveness revisited: Unpredictable temporal isolation does not benefit short-term serial recall of heard or seen events

The notion of a link between time and memory is intuitively appealing and forms the core assumption of temporal distinctiveness models. Distinctiveness models predict that items that are temporally isolated from their neighbors at presentation should be recalled better than items that are temporally crowded. By contrast, event-based theories consider time to be incidental to the processes that govern memory, and such theories would not imply a temporal isolation advantage unless participants engaged in a consolidation process (e.g., rehearsal or selective encoding) that exploited the temporal structure of the list. In this report, we examine two studies that assessed the effect of temporal distinctiveness on memory, using auditory (Experiment 1) and auditory and visual (Experiment 2) presentation with unpredictably varying interitem intervals. The results show that with unpredictable intervals temporal isolation does not benefit memory, regardless of presentation modality.

False positives in recognition memory produced by cohort activation

Cohort theory in spoken-word recognition assumes that a cohort of word candidates consistent with incoming sensory information is activated implicitly as a spoken sound stimulus unfolds over time. Five experiments examined implications of this internal-generation-of-words mechanism. In Experiments 1 and 2, a “base” word was disqualified (the sensory information was no longer consistent with the word) either early or late in the presentation of a spoken stimulus. On a later recognition-memory test, significantly more false-positive errors occurred to base words following presentations of study items that had late, compared to early, disqualification points. Experiments 3–5 tested whether this phenomenon could be accounted for in terms of overlapping features between non-word stimuli and their base words or in terms of a post-identification processing mechanism. Experiment 3 replicated Experiments 1 and 2, and demonstrated that differences in early and late disqualification points for non-word targets, unlike word targets, were not related to false-positive recognition memory errors. The study inter-item interval in Experiment 4 was reduced to 1 s to minimize the role of post-identification processing activities, and the results for both word and non-word targets were consistent with Experiment 3. A word-association task in Experiment 5 revealed that the late non-word derivations used in this research were on the average more effective stimuli than the early non-word derivations in eliciting their base words. However, even when comparisons were restricted to item sets with early and late non-words that were equally effective in eliciting base words, false-positive recognition memory errors to target words were higher following prior presentations of their late derived non-words than following prior presentations of their early derived non-words.

Imaginal Recoding of Numbers

Most mnemonic systems require subjects to use mental imagery of one form or another. For instance, the method of loci and the link method among others both rely on mental imagery in aiding recall. It has often been demonstrated that imagery facilitates recall ( 1 ) . If a method could be devised to recode digital information into visual images, there should be an increase in the number of digits later recalled relative to the number of digits recalled without such imaginal recoding. A mnemonic code was developed to recode digit triplets into visual images. The first digit in a triplet was recoded into an image of an animal, the second into an action and the third into an image of a place. Thereby each triplet was transformed into an image of a particular animal performing a certain action in a specified place. The code contained the words for 10 animals, 10 actions (verbs), and 10 places for the 10 digits in the three positions, respectively. Eight undergraduates were paid for their individual participation in the study. The first part of the procedure was a preliminary control free recall test of 15 random digit triplets. The triplets were presented separately for 8 sec. each with a 1-sec. inter-item interval. A cathode ray tube (Model ADM 3A) controlled by an ADS/1800E process control system was used to present items. The second part of the procedure involved subjects' participation in several code-learning sessions. All subjects were trained in the following manner: They learned separately by rote the three word-number lists, then they learned verbal encoding and decoding of the words and digits associated with each list, and finally, they practiced visualizing the animals performing actions in a place. Each session lasted about 1 hr., and an average of 7.88 sessions per subject occurred over five to nine days. Subjects were trained until a nine-second-per-triplet encoding criterion was met in about 6 to 7 hr. of training. Subjects also had to demonstrate they were using the code by describing some of the images they developed of each triplet in two practice tests prior to the final test. The final test was identical to the control test except that a different set of triplets was used and the subjects were instructed to use the imaginal recoding system and store the items in encoded form. At the time of recall they decoded the items into numbers. Different lists were used with different subjects. The mean number of triplets correctly recalled in the control and in the imaginal recoding conditions were 4.12 and 3.25, respectively. Performance was significantly better in the control condition than in the final test condition ( t , = 2.50, p < .05). The failure of the imaginal recoding to increase recall is consistent with the finding that imagery instructions per se do not increase recall ( 2 ) . A more precise delimitation of conditions of effectiveness of imagery is necessary.

The effects of rehearsal rate on serial recall in Korsakoff amnesia

The relationship between rehearsal and Korsakoff amnesia was investigated for a probed serial-recall task. Alcoholic Korsakoff patients were impaired relative to alcoholic and normal subjects on memory for serial position. This impairment was greatest for words presented early in the list. Alcoholic Korsakoff patients also rehearsed at a slower rate than control subjects. Further, they rehearsed fewer distinct words during each interitem interval. When the effects of lower rehearsal rate were statistically controlled, Korsakoff patients did not differ from control subjects on recall of serial position. These results suggest Korsakoff amnesia is related to rehearsal deficits.

Hemisphere-Specific Processes in Letter Matching.

Three experiments were designed to investigate outstanding questions concerning the effect of memory load variations on efficiency and coding processes in the left and right cerebral hemispheres. In Experiment 1 subjects were presented with one, two, or three target letters in uppercase or lowercase in central vision, followed by simultaneous bilateral probes requiring a name match response. Twenty young right-handed adults, 10 males and 10 females, acted as subjects. Two main features of the results were as follows: (a) The slope of the linear function relating mean reaction time (RT) and set size was 30% greater for right visual field (RVF)-left-hemisphere probe stimuli under both physical and name identity conditions, and (b) RT for RVF-left-hemisphere probes was greater when the probe was drawn from preterminal serial position in the target list. Experiments 2 and 3 examined the proposition that the results of Experiment 1 reflected asymmetric interference during list acquisition. The results showed that, first, the LVF-right-hemisphere advantage was eliminated or reversed under unilateral probe presentation conditions, and second, the LVF-right-hemisphere advantage for a single, preterminal serial position was insensitive to variations in the interitem interval. The results are thought to be inconsistent with the interference hypothesis. The general implications of the results for existing theories of hemisphere function are discussed.

Verbal Processing of Visual Stimuli

Summary Ss were 144 undergraduate men and women who were encouraged or discouraged to use verbal descriptions of presented line drawings; groups also differed in terms of picture exposure time and interpicture interval. Following the presentation of the pictures, the Ss were given a recognition test. It was expected that for the verbal groups, verbal rehearsal would lead to primacy effects and increased retention with increasing interitem interval; these effects would not be found for the nonverbal groups. For both verbal and nonverbal groups, primacy effects and beneficial effects of increasing interitem interval were statistically significant. Verbalization instructions did not have a reliable effect, suggesting that Ss were unable to control processing mode.

A simple device for the preparation of exactly aligned dichotic tapes

A system is described involving three tape recorders and a control device whereby dichotic tapes can be prepared with onset alignment accurate to a few milliseconds, or to a measured asynchrony if required. No modifications of any sort are necessary for the three tape recorders. The two channels are separately recorded in the speaker’s own time, the only requirement being that the separate words be spoken with an interword interval of 350 msec or more, to provide sufficient time for starting and stopping the system. A tone burst is placed directly on tape on another channel ahead of each word, the latter being delayed by recording in tandem through two tape recorders. The first recorder is set to the delay (echo, NAB) facility, while the tone is recorded directly on the second. Subsequently, when this is done for each item on the two speech channels, the device, described below. utilizes the tone bursts to align the two input recorders. It then rerecords each pair of words on to the third (output or dichotic) machine, to the desired synchrony/asynchrony, and interitem interval. The system can be left to align the two channels automatically. A maximum repetition rate of two dichotic pairs every 1.3 sec can be achieved with Revox A77 tape recorders.

Sex Differences in Learning Connected Discourse as a Function of Exposure and Interitem Intervals

Learning of connected discourse was contrasted for males and females for differing exposure and interitem intervals. With total presentation time constant, it was more difficult for males to learn the material when the interitem interval was greater than the exposure interval rather than the reverse. Females appeared to learn equally well under both conditions.

The Effects of Delay, Type, and Duration of Feedback on Verbal-Discrimination Learning

Verbal-discrimination learning was significantly faster when subjects were shown the correct member of the pair (feedback type A) than when shown the spatial position of the correct member (type B). A delay of feedback significantly impaired the rate of learning, whereas an increase in the duration of feedback led to faster learning. Also, delay and type of feedback interacted: the detrimental effects of delay occurred only with feedback B. The results are discussed with reference to comparable paired-associates studies, and interpreted in terms of frequency theory. There have been a number of investigations on the temporal intervals involved in the presentation of individual items in paired-associate learning by the anticipation procedure. According to Ward and Baumeister (1971), at least four such intervals may be distinguished. The durations of exposure for the stimulus and the stimulus-response feedback constitute the 'stimulus interval' and the 'feedback interval' respectively. The delays between the stimulus and the feedback and between the feedback for one item and stimulus exposure for the following item may be referred to as the 'feedback-delay interval' and the 'interitem interval.' The anticipation procedure used in most verbal-discrimination learning also fits this general model. The stimuli, a pair of verbal units, are presented to the subject, who is then given feedback, generally an exposure of the correct unit. He is asked to select one of the units during the 'stimulus interval' and is later informed of the correct choice during a 'feedback interval.' Before turning to the similarities and dissimilarities of paired-associate and verbal-discrimination learning, however, let us first review the literature on paired-associate learning in terms of the two feedback intervals Ward and Baumeister outline: that having to do with the delay between stimulus and feedback and that having to do with the duration of the feedback itself.

Influence of exposure interval and interitem interval on the learning of connected discourse.

Influence of exposure interval and interitem interval on the learning of connected discourse.

Influence of interitem interval in the learning of connected discourse.

DOCUMENT RESUME 214 TE 001 951 King, David J. The Influence of Inter-Item Interval on the Learning of Connected Discourse. Final Report. State Univ. of New York, Oswego. Coll. at Oswego. Office of Education (DHEW) , Washington, D.C. Bureau of Research. BR-8-E-065 Apr 70 OEG-0-8-0800653720 47p. EDRS Price MF-$0.25 BC-42.45 *Connected Discourse, Discourse Analysis, Interval Pacing, *Intervals, Item Analysis, Learning, Learning Processes, *Recall (Psychological) , *Time Factors (Learning), *Verbal Learning This research evaluated the total-time hypothesis for the learning of connected discourse--that in verbal learning fixed amou.tit of time is necessary to learn a fixed amount of material regardless of the number of individual trials into which that time is divided. Learning material consisted of two sets of connected discourse for each of the seven lengths examined--10, 15, 20, 25, 30, 35, and 40 words-in-length. For all 14 passages, each word was typed on a radio-mat slide in preparation for projector presentation with an exposure interval for each word of .5 seconds. The subjects, introductory psychology students assigned to individual treatment on a random basis (except for sex, numerical, and inter-item balance) , were presented with the learning material after a brief explanation. Basic learning data were scored in four ways: the number of trials to criterion, the number of words recalled (not necessarily correctly) on each trial, the number of three-word sequences identical with tho original recalled on each trial, and the number of intrusions in each recall of each subject. Results of the research rejected the total-time hypothesis. (Lengthy appendices contain the learning material and data on the number of trials to criterion, followed by the quantitative and organizational factors, and the results for intrusions.) (JMC) U.S. DEPARTMENT OF HEALTH, EDUCATION d WELFARE OFFICE OF EDUCATION CO THIS DOCUMENT HAS BEEN REPRODUCED EXACTLY AS RECEIVED FROM THE CY PERSON OR ORGANIZATION ORIGINATING IT. POINTS OF VIEW OR OPINIONS CO STATED DO NOT NECESSARILY REPRESENT OFFICIAL OFFICE OF EDUCATION POSITION OR POLICY. FINAL REPORT CD