[The learning of visual binary decision sequences by means of auditory feedback].
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Three experiments investigated a dissociation originally described by Neumann, Esselmann, and Klotz. Stimuli were geometric shapes, preceded by similar shapes that were masked by metacontrast. Each experiment consisted of three parts. In the reaction time (RT) part, participants saw an array of geometric shapes, one of which was marked by bars, and had to respond to the marked shape's position by pressing an appropriate button. A prime (a similar, but smaller stimulus) preceded either the marked or an unmarked stimulus. In the temporal order judgment (TOJ) part, the task was to judge the temporal order of the marked and the unmarked stimulus. In the detection part, detectability of the prime was tested. Although its detectability was zero or close to zero, the prime affected both RT and the apparent onset as measured by TOJ. The effect on RT was significantly larger than the effect on TOJ (Exp. 1). Increasing the spatial context (number of non-target stimuli in the display) did not affect this pattern (Exp. 2). By contrast, reducing the temporal context (range of stimulus onset asynchronies) abolished the prime's effect in the TOJ task, although the prime affected RT under identical conditions. It is concluded that partially different mechanisms mediate the prime's effect in the two tasks and that the effect of stimulus context on TOJ found in the Neumann et al. study was due to temporal, not spatial context.
Working memory (Baddeley and Hitch 1974) incorporates the notion of a visuo-spatial sketch pad; a mechanism thought to be specialized for short-term storage of visuo-spatial material. However, the nature and characteristics of this hypothesized mechanism are as yet unclear. Two experiments are reported which examined selective interference in short-term visual memory. Experiment 1 contrasted recognition memory span for visual matrix patterns with that for visually presented letter sequences. These two span tasks were combined with concurrent arithmetic or a concurrent task which involved manipulation of visuo-spatial material. Results suggested that although there was a small, significant disruption by concurrent arithmetic of span for the matrix patterns, there was a substantially larger disruption of the letter span task. The converse was true for the secondary visuo-spatial task. Experiment 2 combined the span tasks with two established tasks developed by Brooks (1967). Span for matrix patterns was disrupted by a visuo-spatial task but not by a secondary verbal task. The converse was true for letter span. These results suggest that the impairment in short-term visual memory resulting from secondary arithmetic reflects a small general processing load, but that the selective interference due to mode of processing is by far the stronger effect. Results are interpreted as being entirely consistent with the notion of a specialized visuo-spatial mechanism in working memory.
The "reading" of a sequence of narrative pictures has been studied as a specific cognitive area. Sequences of pictures were presented to children between 3 and 7 1/2 years old in either the right or wrong order. We studied four problems: the child's difficulty in seeing the same character throughout different representations, the liking-up process of several pictures into one story, the correlation between the temporal order and the spatial disposition of pictures, and the child's tendency to consider the setting of pictures as a puzzle to solve. The characteristic difficulties observed seem to be related to the double status of the picture, which is both a physical and a symbolic object. We set out to reconstruct the path taken from the initial dilemma in which a child finds herself/himself, caught between the signifier and the signified, up until the point where, all contradictions resolved, she/he definitively acquires the principles of the way in which a sequence of pictures functions. Although more or less distinct stages concerning the acquisition of different rules inherent in a sequence of pictures can be observed, the existence of transitional periods favors a continuous progression.
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Accuracy of report of words in a rapidly presented sequence is reduced if 1 word is a repetition of a previous word. This is repetition blindness. If, however, the items are pronounceable nonwords, or pseudohomophones, repetition improves recall. A repetition advantage for nonwords also occurs when subjects merely count the items or when the item between the critical nonwords is a familiar word. Familiarizing subjects with the nonwords improved the level of recall but did not affect the repetition advantage. These results are considered in relation to token individuation and other accounts of repetition blindness. The findings suggest that for identical linguistic stimuli the types bound to episodic memory tokens that are vulnerable to repetition blindness are lexical units.
In Experiments 1 and 2, subjects were exposed to letter strings that followed a pattern--the second letter was always the same. This exposure was disguised as a test of immediate memory. Following this training, subjects could discriminate new letter strings following the pattern from letter strings not following the pattern more often than would be expected by chance, which is the traditional evidence for concept learning. Discrimination was also better than would be predicted from subjects' explicit report of the pattern, demonstrating the co-occurrence of concept learning and implicit learning. In Experiment 3, rules were learned explicitly. Discrimination was worse than would be predicted from subjects' explicit report, validating the implicit learning paradigm. In Experiment 4, deviations from a prototypical pattern were presented during training. In the test of discrimination, prototypes were as familiar as old deviations and more familiar than new deviations, even when considering only implicit knowledge. Experiment 5 found implicit knowledge of a familiar concept. These results are consistent with the hypothesis that the distinguishing features of a concept can be learned implicitly, and that one type of implicit learning is concept learning.
College students and older adults (mean ages 20.4 and 71.5 years) performed in a "keeping track" task that required them to recall, in response to probe questions, the most recently presented of each of a fixed set of categories. Questions alternated with presentations of new sets of items. Response accuracy, reaction times, and verbal reports provided information on the participants' strategies. The findings were consistent with the view (e.g., Hasher & Zacks, 1979) that older adults' poorer memory results from reduced use of effortful strategies. The older persons used fewer active encoding strategies than the college students and were less accurate and slower to respond. A subgroup of the elderly adults reported some active encoding activities; they performed more like the college students than the remaining elderly participants. A follow-up study in which college students were allowed reduced opportunity for active encoding produced performance intermediate between the other two groups.
A test battery designed to assess cognitive functions normally related to the left and right cerebral hemispheres was validated on 30 patients with unilateral (16 right, 14 left) lesions. The tests were preselected to reflect typical functioning of the hemispheres according to general agreement in the literature. A Cognitive Laterality Quotient (CLQ) was calculated from the difference in performance between the "right" and "left" test batteries and, therefore, reflected the relative functioning attributed to the right and left hemispheres. Using the CLQ measurement and a control group of 30 non-neurological patients matched for age and education, 28 out of 30 brain-damaged patients (93%) were categorised correctly according to side of lesion; the other two were considered to have either abnormal lateralisation (one was left handed) or asymmetrical premorbid cognitive profiles. Using only one (paired) test whose two subparts were designed to vary only slightly in task requirements to measure either right or left functioning, 29 out of 30 patients were correctly categorised. It is suggested that the concept of relative assessment of basic cognitive functions is more fruitful than general assessment of intellectual functions for use in diagnosis and rehabilitation of neurological patients or normal subjects with developmental or acquired behavioural cognitive abnormalities.
This study was conducted to investigate how the mode of stimulus presentation affects recall in the classroom environment. 289 undergraduates were randomly assigned to one of 7 experimental groups. All subjects were presented the same stimuli in one of 7 possible modes: (1) Printed Word, (2) Spoken Word, (3) Picture, (4) Printed Word + Spoken Word, (5) Picture + Spoken Word, (6) Picture + Printed Word, and (7) Printed Word, Picture + Spoken Word. 30 words, 6 from each of 5 categories, were presented to each group. A new stimulus was presented every 5 sec. Subjects were to recall (in writing) as many stimuli as possible in 5 min. regardless of order. One-way between groups analyses of variance were conducted on recall and cluster index scores. A significant main effect of mode of presentation showed that recall was best for the Picture or multimodal group (Printed Word, Picture + Spoken Word). Groups receiving only the spoken or printed word showed significantly poorer recall than the multimodal groups. No statistically significant differences between groups were found on the cluster index score. It appears that the simultaneous presentation of redundant stimuli in multiple modalities does support the multiple-resource hypothesis by displaying enhanced recall when information is available from multiple attentional resources.
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Memory for temporal order information was examined in patients with chronic schizophrenia using the recency discrimination task. In this task, subjects were shown a pair of previously studied words and were asked to choose which one of the two words they had seen more recently. In addition, subjects performed the Wisconsin Card Sorting Test (WCST). The results showed that schizophrenic patients differed from normal control subjects in their performance on the recency discrimination task. In addition, for schizophrenic patients, performance on the recency discrimination task was inversely related to the number of perseverative errors on the WCST. These results provide further evidence of prefrontal-type cognitive deficits in schizophrenia.
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In this study, the performance of amnesic patients with presumed temporal lobe damage was compared with that of patients with presumed diencephalic damage using the temporal list discrimination task. The two patient groups performed similarly on a measure of recognition, but the diencephalic group was impaired relative to the temporal lobe group on a measure of temporal discrimination. Discrimination performance in the temporal lobe group was significantly correlated with recognition memory. The data are interpreted as showing a qualitative difference in the form of amnesia arising from damage centred on the medial temporal lobes compared with that centred on the midline diencephalon.
Rats with lesions in either the fornix or the thalamic nucleus medialis dorsalis were unimpaired on the acquisition of two object discrimination tasks. The same animals were then tested on a concurrent learning task in which various object discriminations were presented at different rates during the same session. This arrangement was primarily designed to minimise any response bias effects. Animals were able to acquire the various concurrent tasks, even when only one trial per day was given for a particular discrimination. It was found that fornix lesions had little or no effect and only produced a mild impairment when the rate of stimulus presentation resembled that used in typical concurrent tasks. Lesions of medialis dorsalis produced a more general, but again mild, deficit. In a final task, the animals were trained to discriminate between two stimuli composed of common elements arranged in different spatial combinations. Fornix lesions impaired acquisition of this spatial configural discrimination, while lesions of medialis dorsalis had a variable effect. The results indicate that fornix lesions can spare concurrent discrimination learning, and that any deficits may be related to interference effects associated with common elements in the stimuli. Lesions in medialis dorsalis appear to affect the initial learning of reward-based performance rules.
We recently demonstrated that rats with dorsal anterior cingulate (ACd) cortical lesions were disrupted in the acquisition of a temporal Go/No-Go alternation task, suggesting either an involvement of this medial prefrontal subregion in sequencing temporally ordered behaviors or alternatively in more general response selection processes 'Gisquet-Verrier et al., Psychobiology 28 (2000) 248'. In the present study, the effects of ACd lesions were investigated in two different training situations. Both tasks involved response selection but only one of the two tasks required behavioral sequencing. In experiment 1, rats with ACd lesions were normally able to select Go and No-Go responses, when selection processes were based on a tone/light conditional rule that does not require temporal patterning. In experiment 2, ACd-lesioned rats were disrupted during the acquisition of a spatial alternation task that relies on temporal patterning. These results provide further evidence of ACd involvement in behavioral sequencing, regardless of the nature (spatial or non-spatial) of chained responses. A comparison of ACd lesions-induced effects with those obtained with lesions to the adjacent prelimbic-infralimbic area 'Delatour & Gisquet-Verrier, Behav. Neurosci. 110 (1996) 1282; Delatour & Gisquet-Verrier, Behav. Neurosci. 113 (1999) 941' reveals a double dissociation of these two regions that reflects a functional regionalization of the medial prefrontal cortex in the rat.
Rats with parietal cortex lesions were tested for both item and order memory for a list of spatial events in a probe recognition procedure. Rats with parietal cortex lesions were impaired for all events within the item memory task but had good memory for the early events within the order memory task. These data suggest a dissociation of function between item and order memory for parietal cortex damaged animals. In conjunction with previous findings with rats with medial prefrontal cortex lesions, these data suggest that item and order memory can be coded and represented independently.
The contribution of hippocampal and nonhippocampal memory processing to simultaneous-cue odor discrimination learning was assessed. In this task, rats with hippocampal system damage consequent to fornix lesions (fornix rats) were severely and persistently impaired in discrimination learning, acquisition of learning set, and concurrent discrimination, although they occasionally solved some problems at a normal rate. By using those problems on which fornix rats succeeded, to permit comparisons of performance strategies with normal rats, differences between groups were shown on response latency measures and on probe trials involving the novel pairing of familiar odors. Normal rats had a bimodal distribution of response latencies, and their latency depended on where the S+ was presented. Fornix rats had short response latencies and responded equally quickly wherever the S+ was presented. Furthermore, when the representation of familiar S+ and S- odor pairs was challenged in probe trials, normal rats responded appropriately to the correct stimulus, whereas fornix rats behaved as if presented with a new odor pair. These data provide support for the view that the hippocampus participates in the representation of relations among odor (and other) stimuli and among other experiences and that it permits the flexible use of these representations in new contexts. In contrast, memory processing outside the hippocampal system can represent only the significance of individual stimuli and can be revealed only in a repetition of the original learning event.