High Memory Load Research Articles

Working Memory Capacity in High Trait-anxious and Repressor Groups

The verbal reasoning performance of high-anxious (high trait anxiety, low defensiveness), defensive high-anxious (high trait anxiety, high defensiveness), repressor (low trait anxiety, high defensiveness), and low-anxious (low trait anxiety, low defensiveness) groups was examined under high and low memory load conditions. As predicted by the processing efficiency theory (Eysenck & Calvo, 1992), the slowing of reasoning speed with the high memory load was disproportionately great for the high-anxious and defensive high-anxious groups. The effects of high memory load on reasoning speed were the same for the low-anxious and repressor groups, suggesting that both groups had equivalently low levels of worrying (and other anxiety related) task-irrelevant thoughts. Theoretical implications of these, and other findings, for the understanding of repressors were discussed.

A Working Memory Model of a Common Procedural Error

Systematic errors In performance are an important aspect of human behavior that have not received adequate explanation. One such systematic error is termed postcompletion error; a typical example is leaving one's card In the automatic teller after withdrawing cash. This type of error seems to occur when people have an extra step to perform in a procedure after the main goal has been satisfied. The fact that people frequently make this type of error, but do not make this error every time, may best be explained by considering the working memory load at the time the step is to be performed: The error is made when the load on working memory is high, but will not be made when the load is low. A model of performance In the task was constructed using Just and Carpenter's (1992) CAPS that predicted that high working memory load should be associated with postcompletion errors. Two experiments confirmed that such errors can be produced in a laboratory as well as a naturalistic setting, and that the conditions under which the CAPS model makes the error are consistent with the conditions under which the errors occur in the laboratory.

A working memory model of a common procedural error

Systematic errors In performance are an important aspect of human behavior that have not received adequate explanation. One such systematic error is termed postcompletion error; a typical example is leaving one's card In the automatic teller after withdrawing cash. This type of error seems to occur when people have an extra step to perform in a procedure after the main goal has been satisfied. The fact that people frequently make this type of error, but do not make this error every time, may best be explained by considering the working memory load at the time the step is to be performed: The error is made when the load on working memory is high, but will not be made when the load is low. A model of performance In the task was constructed using Just and Carpenter's (1992) CAPS that predicted that high working memory load should be associated with postcompletion errors. Two experiments confirmed that such errors can be produced in a laboratory as well as a naturalistic setting, and that the conditions under which the CAPS model makes the error are consistent with the conditions under which the errors occur in the laboratory.

Repeatability of Magnitude Production in Isometric, Hand-Grip Force Estimation: A Working-Memory Approach

Magnitude production has been used in ergonomics research to quantify hand-grip and finger-pinch force exertions. The repeatability of this psychophysical method may be affected by a memory component if the subject must recall multiple, previously performed force exertions. This investigation tested the hypothesis that the number of different to-be-remembered hand-grip force exertions would affect the repeatability of force productions obtained via magnitude production for 12 male students. Four levels of force were examined (20%, 35%, 50%, and 65% of subject's individual maximum) at low and high memory loads (two versus four forces to be remembered concurrently). Amount of force had a significant effect on the variance among a sample of five observations; however, memory load showed no effect on the variance measure. Thus, it is concluded that four forces do not pose a significantly greater memory load than two forces for perceived force in hand-grip magnitude productions.

Heart rate and heart-rate variability during hypnotic responding

Humans have limited capacity of processing just up to 4 integrated items of information in the working memory. Thus, it is inevitable to commit more errors when challenged with high memory loads. However, the neural mechanisms that determine the accuracy of response at high memory loads still remain unclear. High temporal resolution of Electroencephalography (EEG) technique makes it the best tool to resolve the temporal dynamics of brain networks. EEG-defined microstate is the quasi-stable scalp electrical potential topography that represents the momentary functional state of brain. Thus, it has been possible to assess the information processing currently performed by the brain using EEG microstate analysis. We hypothesize that the EEG microstate preceding the trial could determine its outcome in a visuospatial working memory (VSWM) task. Twenty-four healthy participants performed a high memory load VSWM task, while their brain activity was recorded using EEG. Four microstate maps were found to represent the functional brain state prior to the trials in the VSWM task. One pre-trial microstate map was found to determine the accuracy of subsequent behavioural response. The intracranial generators of the pre-trial microstate map that determined the response accuracy were localized to the visuospatial processing areas at bilateral occipital, right temporal and limbic cortices. Our results imply that the behavioural outcome in a VSWM task could be determined by the intensity of activation of memory representations in the visuospatial processing brain regions prior to the trial.

Neural mechanisms underlying melodic perception and memory for pitch

The neural correlates of music perception were studied by measuring cerebral blood flow (CBF) changes with positron emission tomography (PET). Twelve volunteers were scanned using the bolus water method under four separate conditions: (1) listening to a sequence of noise bursts, (2) listening to unfamiliar tonal melodies, (3) comparing the pitch of the first two notes of the same set of melodies, and (4) comparing the pitch of the first and last notes of the melodies. The latter two conditions were designed to investigate short-term pitch retention under low or high memory load, respectively. Subtraction of the obtained PET images, superimposed on matched MRI scans, provides anatomical localization of CBF changes associated with specific cognitive functions. Listening to melodies, relative to acoustically matched noise sequences, resulted in CBF increases in the right superior temporal and right occipital cortices. Pitch judgments of the first two notes of each melody, relative to passive listening to the same stimuli, resulted in right frontal-lobe activation. Analysis of the high memory load condition relative to passive listening revealed the participation of a number of cortical and subcortical regions, notably in the right frontal and right temporal lobes, as well as in parietal and insular cortex. Both pitch judgment conditions also revealed CBF decreases within the left primary auditory cortex. We conclude that specialized neural systems in the right superior temporal cortex participate in perceptual analysis of melodies; pitch comparisons are effected via a neural network that includes right prefrontal cortex, but active retention of pitch involves the interaction of right temporal and frontal cortices.

Individual differences in anxiety and the restriction of working memory capacity

M.W. Eysenck has proposed that the performance deficits often associated with elevated levels of anxiety reflect an underlying restriction in the functional capacity of working memory. The current experiment was designed to test this account, by contrasting the performance of 24 high anxiety and 24 low anxiety students on a grammatical reasoning task performed under two simultaneous memory load conditions. As anticipated, the high anxiety group did indeed show disproportionately long decision latencies on this reasoning task. Furthermore, the effects of the simultaneous memory load manipulation were fully consistent with predictions derived from Eysenck's theoretical account of this performance deficit. Specifically, although all subjects were slower to perform the reasoning task under the high simultaneous memory load condition, this slowing was disproportionately severe for the high anxiety subjects. It is argued that these results provide support for Eysenck's proposal, that a restriction in working memory capacity underlies the performance deficits commonly shown by highly anxious individuals.

Wayfinding by Newcomers in a Complex Building

We conducted several experiments to determine the characteristics of an optimal wayfinding aid for new users of a complex building. In Experiment 1 wayfinders who used signs found their destinations fastest. Those using you-are-here maps were much slower than even those wayfinders given no aids. The main advantage of signs over you-are-here maps results from information-processing differences: Signs provide clear cues about turns and decisions without requiring study time or imposing a high memory load. In Experiment 2 we found that people prefer routes that require the least amount of energy expenditure. Contrary to findings of previous research, we did not find complexity to be an important variable. A third experiment, using artificial floor plans of buildings, confirmed that minimizing energy is much more important than complexity in determining preferred routes. Finally, in Experiment 4, we investigated wayfinders' heuristics and the information necessary to provide unambiguous signs.

Reading and Visual Memory: Remembering Scenes That Were Never Seen

In Experiment 1 (N = 16), under conditions of high memory load (60 pictures and 50 paragraphs) and a 1-week retention interval, undergraduate subjects reported their memory for photographs of scenes (cued recall and free-recall tasks). Subjects frequently reported memory for photographs that they had actually never seen, but had read about in a brief paragraph. In Experiment 2 (N = 40), the same pattern of results was obtained with immediate testing. Experiment 2 also demonstrated that the likelihood of subjects falsely attributing scene memory (based on reading) to actually having viewed a photograph was reduced when metacognitive awareness of imaging during reading was made salient. Awareness of image creation was induced by requiring subjects to rate the paragraphs with respect to imagery vividness. Although other measures of memory remained the same, subjects in the induced-imagery condition made 50% fewer confusion errors than subjects who read the paragraphs without imagery instructions. The results are discussed in the context of Johnson and Raye's (1981) reality monitoring model.

Aging increases the energetic demands of episodic memory: A cardiovascular analysis.

We hypothesized that older volunteers allocate more attentional resources to memory maintenance than do younger volunteers. Allocation of a resource supporting memory maintenance was inferred from performance and cardiovascular measures. Eighteen 18- to 26-year-old men and eighteen 60- to 79-year-old men performed a serial memory task both as a single task and as a dual task that added simple reaction time stimuli. Items presented early or later in the serial list created relatively low or high memory load. The results suggested that older men allocated greater attention to memory maintenance, particularly during high-memory-load items. They showed a slowing of dual-task reaction time and increased heart rate during high- vs. low-memory-load items. Cardiac and vascular reactions further suggested that memory maintenance is supported by phasic autonomic adjustments and that with age, more of this support is required for adequate maintenance of episodic memory.

Early and late selection in young and old adults: an event-related potential study.

ABSTRACTThe present experiment investigated differences in processing between young and old adults in a combined visual selection‐memory search paradigm. No evidence was found for age‐related differences in early visual selective attention. The elderly achieved relatively fast reaction times in the memory search task at the cost of a high error percentage. From these findings, and from the morphology of the event‐related potential, it was concluded that old subjects perform controlled memory search more superficially than young subjects, In both old and young subjects high memory load was associated with decreased positivity in the P3 and Slow Wave area. This is interpreted in terms of Okita et al.'s(1985) concept of search negativity. N2 amplitude was found to be larger to non‐target trials for both attended and unattended inputs. The latter result is discussed in relation to theories about N2 as an indicator of automatic mismatch detection.

Sex differences in the effects of noise and nightwork on performance efficiency

Abstract An experimental investigation of the combined effects of noise and nightwork revealed the following sex differences. Female subjects showed a large night-time impairment on a test of manual dexterity, but performed working memory tasks better at night than in the day. In contrast to this, male subjects showed a small impairment at night on both types of task. Other tasks, such as the simple reaction time task, were impaired at night for both sexes, and some tasks, such as the high memory load search task, showed no night-time impairment in males or females. There was no evidence of noise producing different effects in the two sexes, and few instances of sex differences in the size of post-meal impairments. Overall, these results show mat the effect of working at night depends on the nature of the task and also the sex of the person performing it.

The combined effects of occupational health hazards: an experimental investigation of the effects of noise, nightwork and meals.

An experimental study of the effects of noise, nightwork and meals showed that these factors influenced different aspects of performance. Speed of performing a low memory load version of a visual search task was influenced by working at night but was unaffected by either noise or meals. A high memory load version of the search task was performed more slowly after consumption of a meal, both during the day and at night, but was not influenced by nightwork. Subjects working in noise produced more errors on the high memory load task than those working in quiet, but neither nightwork nor meals had significant effects on the number of errors. The only evidence of an interaction between factors was obtained in the high memory load search task, where noise reduced the size of the post-meal decline in speed. These results show that the effects of noise, nightwork and meals are largely independent, the exception being the beneficial effect of noise on post-lunch performance. They also demonstrate that the effects of all of these factors depend on the nature of the task being performed, and on whether speed or accuracy is the variable under consideration.

A case study of reproduction conduction aphasia II: Sentence comprehension

Abstract We present data regarding assignment of thematic roles to noun phrases by RL, a reproduction conduction aphasic, in semantically reversible sentences with a variety of syntactic structures. RL makes systematic errors in sentence interpretation. With auditory presentation of sentences, he has difficulty with sentences containing relative clauses in subject position. This is consistent with his having difficulty due to a high local memory load imposed by these structures. With written presentation, RL does not distinguish three sentence types which contain the sequence NP-V-NP-V-NP. His pattern of results suggests that he does not recognise that verbs are embedded or conjoined in the sentence types in question. This may reflect the absence of prosodic cues to syntactic structure in written material. In both modalities, RL has some difficulty with passive morphology, but distinguishes passive from active sentences. The pattern of results with auditory presentation suggests that memory stores and structure-building operations internal to a sentence parser-interpreter are impaired in RL. We consider the relationship between aspects of working memory and sentence parsing-interpretation on the basis of this case and other cases in the recent neuropsychological literature.

The interactive effects of caffeine, impulsivity and task demands on a visual search task

Humphreys and Revelle (1983) have suggested that arousal hinders short-term memory processes but facilities attentional processes. In a conceptual replication of a study of body temperature and performance (Folkard et al., 1976), 84 undergraduates classified as low or high impulsive were given either caffeine or placebo. Two versions of a visual search task, one with a 2-letter target (a low memory load task) and one with a 6-letter target (a high memory load task), were used. As predicted, caffeine differentially affected the two tasks: subjects given caffeine detected a lower proportion of 6-letter targets but a greater proportion of 2-letter targets than did subjects given placebo. An unexpected interaction between Impulsivity, Task Sequence and Target Size suggested that high and low impulsives may have adopted different strategies or may have experienced different motvational states during the course of the experiment. The relevance of these data to Easterbrook's (1959) explanation of the Yerkes-Dodson effect is also discussed. These results are consistent with the assumption that there is an arousal dimension which is common to both caffeine and body temperature, and that this dimension is central to the observed pattern of performance.

Individual differences in field articulation as a factor in language comprehension

Previous research has suggested that performance differences associated with field independence/field articulation (FA) reflect differences in the efficiency of a limited capacity “working memory” (WM) system. An information-processing analysis of language comprehension suggests the involvement of WM. This experiment tested the hypothesis that performance differences in a language comprehension task could be predicted on the basis of level of FA and the mediating role of WM. Three levels of memory load were established by varying the logical structure of sets of semantically related sentences which subjects were required to integrate. In the low memory load condition, there was no difference between high and low FA subjects on a test of integration (inference) and specific memory (recognition). In the high memory load condition, there was a decline in performance for low FA subjects on both inference and recognition. Other aspects of the results suggested that the breakdown in information processing, for low FA subjects in the high memory load condition, occurred during or shortly after initial encoding of the sentences.

Memory based performance measures in studies of shiftwork.

The phase of the circadian rhythm in performance efficiency on a given task is known to be influenced by the memory load involved. Two experiments were performed to determine whether memory load also influences the rate at which rhythms adapt to the phase-shifts involved in (a) transmeridian flight and (b) a long period of nightwork. In the first study, high and low memory load versions of a performance test were given to a 25 y old female subject experiencing a 5h eastward change in time-zone. Differences were found both in the initial phase of the two versions of the test and in the rate at which this phase adapted to the new time. In the second study, two young male subjects, working 21 consecutive night shifts, were given high and low memory load versions of the performance test, and a calculations test, every 4 h around the clock. The results were similar to those of the first study: a cosinor analysis revealed that despite periods of arhythmicity there were large differences between the rate of adap...

From individual to group impressions: Availability heuristics in stereotype formation

When subjects are presented with information about the attributes of individuals and are then asked to make judgments about the characteristics of the group composed of those individuals, the group impression may depend on the way in which data on individuals are organized in memory. Experiment 1 demonstrated that under conditions of low memory load (16 instances of person-trait pairings), subjects organize their perceptions of a group around the characteristics of its individual members, whereas under high memory load (64 instances of person-trait pairings), subjects organize trait information in an undifferentiated way around the group as a whole. Under low memory load, subjects distinguish between repeated occurrences of a trait in the same individual and comparable repeated occurrences of that trait in different individuals; under high memory load, subjects do not make such a differentiation. Subjects' judgments about the frequency of categories of traits were related to the ease of recall of category instances, as predicted by an availability heuristic. Experiments 2 and 3 demonstrated that group members who are most available in memory will be disproportionately represented in the group impression. Specifically, the proportion of extreme individuals in a group was retro-spectively overestimated; this was true for both physical stimuli (height) and social stimuli (criminal acts).

Memory-load and concreteness in the order of dominance effect for verbal concepts

Previous research has shown that concrete concepts are more readily attained than abstract concepts. This order of dominance phenomenon has been well established for figural concepts and has been suggested for verbal concepts. In the present study the effect was confirmed for verbal materials, even when the instances and concepts were equivalent with respect to instance frequency, meaningfulness, and conjoint frequency. In addition, the dominance effect was especially marked under high memory-load conditions, and for subjects who had difficulty in remembering previously presented instances. These findings were interpreted to support a new theory of the order of dominance effect for verbal materials: Concrete concepts are in part more readily attained because, under the high memory-load for previous instances which was obtained in earlier experiments, concrete word instances are more readily available from memory.

The Effect of Memory Load on the Circadian Variation in Performance Efficiency Under a Rapidly Rotating Shift System*

Experimental shift work studios have typically found body temperature and performance efficiency to show very similar circadian rhythms. However, the performance tasks used have placed little, if any, reliance on short term memory. Studies of the variation in performance during the normal waking day have found performance on most tasks to improve over the day but that on short term memory tasks to decrease. The present paper reports an experimental study of the performance of two subjects on a rapidly rotating (-2-2) shift system. Three versions of a now performance test, each with a different memory load, wore administered four times per shift. With the low memory load version, performance showed a high positive correlation with body temperature and was poor during the night shift. However, with the high memory load version, performance was negatively correlated with temperature and was best during the night shift. It is concluded that future shift work studies must take into account the memory load of t...