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Negative priming in associative learning: evidence from a serial-conditioning procedure.

Three experiments investigated the suggestion that a predicted or primed stimulus commands less processing and consequently elicits a weaker conditioned response (CR) than a stimulus that is not primed. In each experiment rats received initial training in which the presentation of each of 2 serial compounds, A-X and B-Y, was followed by the delivery of food. Subsequently, X's capacity to elicit the CR, approaching the site of food delivery, was assessed when X was preceded by Stimulus A (i.e., primed) or was presented after Stimulus B. Stimulus X elicited a more vigorous response when it was presented after B than when it followed A. These results show that the ability of one event to elicit its CR is reduced if its presentation has been predicted by some other event. This negative priming effect supports one aspect of Wagner's (1981) model of Pavlovian conditioning.

Animals↗

The recall of digits by normal, deaf and autistic children.

Normal, autistic and deaf children were tested for their immediate memory of visually presented digits. The digits were exposed either with or without a left to right spatial display arrangement, and had to be recalled forewards as well as backwards. Normal and deaf children tended to be sensitive to both display conditions and recall requirements whereas autistic children were mainly affected by direction of recall. Serial position effects in the normal and deaf groups were more dependent on order of retrieval than on input order.

Autistic Disorder↗

Construct validity of various verbal and visual memory tests.

Factor analysis was conducted on attention, information processing, verbal and visual memory scores of 112 patients. Factor structure did not vary as a function of age. The Expanded Paired Associates Test, Verbal Selective Reminding Test, Continuous Recognition Memory Test, and Continuous Visual Memory Test defined a general memory factor. The PASAT, WMS Mental Control, and WAIS-R Digit Span defined an attention/information processing factor. Immediate Visual Reproduction (VR) loaded primarily on visual/nonverbal intelligence, whereas delayed VR loaded primarily with the memory factor. The Trail Making Test, Part B was more closely associated with visual/nonverbal intelligence than with attention/information processing. Serial Digit Learning was more closely associated with attention/information processing than with general memory.

Adolescent↗

Modulation of brain magnetic activity by different verbal learning strategies.

In this study we examined spatiotemporal profiles of brain activity in the context of tasks designed to engage different verbal learning strategies (serial order, phonological, and semantic). The profile of activation associated with the serial-order strategy, which resulted in poor recall performance, featured early activation of the inferior frontal, sensorimotor, and insular region in the left hemisphere, between 200 and 400 ms after stimulus onset. Subsequently, activation was more prominent in dorsolateral prefrontal cortices bilaterally. In contrast, activation profiles associated with the phonological strategy featured predominantly activation of the superior temporal gyrus in the left hemisphere between 500 and 600 ms. Predominant activation of the left middle temporal gyrus, between 500 and 700 ms, was the key feature of the activation profile observed when the semantic elaboration strategy was utilized. These results suggest that different brain circuits are engaged to support learning of new verbal information as a function of the level and type of initial processing applied to the stimuli.

Adult↗

Stimulus novelty and significance as determinants of electrodermal responsivity: the serial position effect.

Three experiments examined the effects of stimulus novelty and significance on the skin conductance component of the orienting response. The test stimuli used in the different experiments involved either a neutral change in stimulation (i.e., adding or deleting components to the standard stimuli), or an introduction of a significant element to the standard stimulus. The serial position of the test stimulus was manipulated in all three experiments. In Experiment 1, nonsignificant test stimuli were introduced at the second, fourth, sixth, or eighth trial of the complex sequence of eight stimuli (i.e., a sequence comprised of varying standard stimuli). None of the test stimuli produced enhanced skin conductance responses under these conditions. Experiment 2 utilized the same design with only one difference: the test stimuli were presented following a simple stimulus sequence (i.e., repetition of a fixed standard stimulus). In this design enhanced skin conductance responses to the test stimuli were observed in almost all experimental conditions, with an advantage of a late over an early presentation of the test stimulus. Experiment 3 was designed to compare serial position effects of significant and neutral test stimuli. A serial position effect was obtained only for the neutral test stimuli, showing once again an advantage for late presentations. It was suggested that different mechanisms might underlie skin conductance responses to significant stimuli and to novel neutral stimuli.

Adult↗

Pauses and durations exhibit a serial position effect.

This article reports evidence of two kinds of serial position effects in immediate serial recall: One involves interresponse pauses, and the other response durations. In forward and backward recall, responding was faster at initial and final positions than at center positions, exhibitinga bow-shaped function relative to serial position. These data were obtained in a spoken recall study in which ungrouped lists of four to six words and postcuing of recall direction were used. The pause pattern is consistent with several models of serial memory, including a distinctiveness model (Brown, Neath, & Chater, 2002) and a version of the ACT-R model augmented with a spontaneous grouping strategy (Maybery, Parmentier, & Jones, 2002). The duration pattern suggests that response articulation depends on the processing context, rather than being modular.

Attention↗

The effects of methylphenidate on repeated acquisition of serial discrimination reversals.

Rats were trained to bar-press for sucrose solution in the presence of one of two stimulus conditions. On each daily training session, the stimulus during which bar-pressing was reinforced was reversed. The subjects were trained in this Serial Discrimination Reversal procedure until successive acquisitions of the discrimination had stabilized. Drug treatments consisting of saline or 0.25, 1.0, 2.0, 4.0, 6.0 or 8.0 mg/kg of methylphenidate were then administered 20 min prior to the daily training sessions. Acquisition of the discrimination was enhanced by low doses of methylphenidate (1,2, and 4 mg/kg) and attentuated by higher doses (6 and 8 mg/kg).

Animals↗

Detectability as a function of spatial location: effects of selective attention.

In a series of previous reports we have described differences in detectability of a target in a background of nontarget patterns as a function of its spatial location. These differences, referred to as a "detectability gradient," have been attributed to target detection accomplished by a serial processing mechanism--a scan. The mathematical model of such a mechanism, developed in the previous report, is equally applicable to a series of attentional shifts or to a perceptual, i.e., a preattentive, mechanism. The present experiments were designed to test the hypothesis that this scan is attentional in nature. The results provide additional evidence for the scanning hypothesis but do not support the view that this scan represents a series of attentional shifts.

Adult↗

A comparison of the effects of frontal cortical and thalamic lesions on measures of spatial learning and memory in the rat.

Two experiments were conducted to compare the effects of radiofrequency lesions of thalamus and frontal cortex on three measures of spatial learning and memory: delayed non-matching to sample (DNMTS), radial arm maze with imposed delays, and serial reversal learning. Thalamic lesions were aimed at the lateral internal medullary lamina (L-IML) and cortical lesions at the projection areas of the mediodorsal nucleus along the medial wall (MW) and dorsal to the rhinal sulcus (RS) in frontal cortex. In Experiment 1 rats were trained on DNMTS prior to surgery. After recovery, rats with MW lesions showed persistent deficits on DNMTS that were significantly greater than for RS lesions. The deficits observed in MW lesioned animals were comparable to the effects of L-IML lesions on this task that have been described in previous studies. In Experiment 2 animals were trained to perform the radial arm maze task prior to treatment. After recovery, animals with L-IML lesions were impaired on the radial arm maze and on subsequent acquisition of the serial reversal task. Rats with RS and MW lesions showed transient impairments on the radial arm maze task, but otherwise performed as well as controls on both these tasks.

Animals↗

Serial sevens versus world backwards: a comparison of the two measures of attention from the MMSE.

This paper reports on a comparison of the two alternative tests of attention in the Mini-Mental State Examination (MMSE), a well-known cognitive screening tool. The two tests, serial subtraction by seven and backwards spelling of the word world, are often used interchangeably. In a large population-based sample, the two tests were found to be weakly associated with each other, with the former test appearing more difficult, although both were strongly associated with educational level. The authors discuss the implications of this finding in clinical and research settings, and make recommendations for more consistent use of the instrument.

Aged↗

Effects of prenatal alcohol exposure on serial pattern performance in the rat.

The effect of prenatal alcohol exposure on serial-pattern learning was investigated in adult rats. Pregnant dams were administered a liquid diet which contained 35% ethanol-derived calories (35% EDC) on days 6-20 of gestation. Two control groups were included: a liquid diet control which was pair-fed and had sucrose substituted for ethanol (0% EDC); and a group fed standard lab chow throughout pregnancy. Offspring from each of these prenatal groups were trained to run a straight alley for food pellets. Pellet amount on successive trials was 14, 7, 3, 1, 7. Subjects were exposed to this pattern four times a day for 8 consecutive days. The mean latency to enter the goal-box for the four trials that comprised a monotonically decreasing series of pellet amounts (14, 7, 3, 1) was indirectly related to pellet amount. The mean latency on each trial and the degree of change in running speed across trials was found to be directly related to in utero alcohol exposure. Alcohol exposed offspring demonstrated less change in latencies over trials than controls. Also, the mean latency on the last trial for 7 pellets was shorter than that seen on the previous trial (1 pellet) and similar to that seen after the first trial in which 7 pellets were available. This indicated that satiation was not a factor in the increasing latencies. These data indicate a deficit in serial pattern performance as a function of prenatal alcohol exposure similar to what is observed in children with FAS.

Animals↗

Topographical changes in alpha power in medicated and unmedicated schizophrenics during digits span reverse matching test.

The topographical distribution of alpha power reduction was compared in nine unmedicated schizophrenics (predominantly never-treated), 17 medicated schizophrenics, and 15 normal controls. The task involved four procedures: (1) listening to signal sound, (2) listening to digits for memorization, (3) after listening, and (4) listening to digits for recognition. The electroencephalograms (EEGs) during each procedure were analyzed with Fast Fourier Transformation and compared with EEGs at rest. While listening to the digits, medicated schizophrenics showed less alpha power reduction than normal controls and unmedicated schizophrenics. In addition, there were correlations found between the degree of alpha power reduction and medication dose, and score of chronic symptoms. These suggest that patients with different clinical backgrounds have differing cerebral activity.

Adult↗

Auditory and visual verbal short-term memory in aphasia.

Phonological short-term memory was investigated in 24 aphasic left brain-damaged patients and in 12 matched controls. Aphasic patients have a reduced auditory and visual immediate memory span and show the standard detrimental effect of phonological similarity on immediate retention only when the stimuli are auditorily presented, while in the control group the effect is present with both auditory and visual input. Most patients have phonological processing deficits, but two patients have an impaired immediate verbal memory in the absence of analysis disorders. These results, in line with most individual case studies of patients with selective deficits of verbal short-term memory, are interpreted with reference to a model distinguishing a phonological short-term store component of memory, to which auditory input has direct and automatic access, and a rehearsal component, that, after phonological recoding, conveys visually presented stimuli to the phonological store. This latter system, that appears to become fully operational later in development, is less resistive to brain damage.

Adult↗

Simultaneous and successive associations in sensory preconditioning.

Four experiments used a novel stimulus sequence to compare simultaneous and sequential associations among neutral stimuli in a sensory preconditioning procedure. In Experiments 1, 2, and 4, rats received a sequence of the form AB-B' in which A was simultaneous with B but sequential with B'. Subsequently, either B or B' was conditioned, and the response to A assessed. This procedure matches the context of A's presentation in comparing its sequential association with B' and its simultaneous association with B, something that prior paradigms have neglected. Experiment 3 used an analogous B'-AB procedure to compare simultaneous and backward associations. Experiments 1-3 used a flavor-aversion procedure in which A, B, and B' were flavors and lithium chloride was the reinforcer. Experiment 4 used conditioned suppression with auditory and visual stimuli and shock reinforcer. All four experiments found simultaneous associations between A and B to be substantial. Moreover, in all cases, conditioning of B produced a greater response to A than did conditioning to B', which suggests that simultaneous associations are stronger than are sequential ones when this paradigm is employed.

Animals↗

Evidence for auditory temporal distinctiveness: modality effects in order and frequency judgments.

Two new, long-lasting phenomena involving modality of stimulus presentation are documented. In one series of experiments we investigated effects of modality of presentation on order judgments. Order judgments for auditory words were more accurate than order judgments for visual words at both the beginning and the end of lists, and the auditory advantage increased with the temporal separation of the successive items. A second series of experiments investigated effects of modality on estimates of presentation frequency. Frequency estimates of repeated auditory words exceeded frequency estimates of repeated visual words. The auditory advantage increased with frequency of presentation, and this advantage was not affected by the retention interval. These various effects were taken as support for a temporal coding assumption, that auditory presentation produces a more accurate encoding of time of presentation than does visual presentation.

Adult↗

Does organization improve priming?

In five experiments, the effects of organization on implicit memory or priming tests were compared with its effects on the explicit memory tests of free and cued recall. Organization was manipulated by varying list structure (blocked vs. random presentation of categorized items) and by instructions. The results showed that organization had parallel effects on the category-production priming test and free- and cued-recall tests; performance was enhanced by organization on both types of tests. It was also demonstrated that the effect of organization on priming was limited to the category-production test and was not obtained with the word-identification priming test. These results suggest that performance on implicit and explicit memory tests is similarly affected by experimental manipulations when both types of tests rely on conceptually driven processing. In addition, performance on two implicit tests is dissociated when one test relies on conceptually driven processing and the other on data-driven processing.

Adult↗

Sequence effects in the categorization of tones varying in frequency.

In contrast to exemplar and decision-bound categorization models, the memory and contrast models described here do not assume that long-term representations of stimulus magnitudes are available. Instead, stimuli are assumed to be categorized using only their differences from a few recent stimuli. To test this alternative, the authors examined sequential effects in a binary categorization of 10 tones varying in frequency. Stimuli up to 2 trials back in the sequence had a significant effect on the response to the current stimulus. The effects of previous stimuli interacted with one another. A memory and contrast model, according to which only ordinal information about the differences between the current stimulus and recent preceding stimuli is used, best accounted for these data.

Humans↗

Memory self-ratings and objective test performance in a normal elderly sample.

Self-rated decline in memory relative to estimated abilities at age 60 was investigated in a group of 88 normal elderly subjects age 60 to 90. Self-ratings of storage, retrieval, attention/concentration, remote memory, and depression formed a factor which was orthogonal to objective measures of memory function. Self-rated remote memory was also associated with objective measures of recent/remote memory, and self-rated depression was additionally related to objective measures of attention/concentration.

Aged↗