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Results for “Reversal Learning”

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At least 1,009 records · Page 56Linked to original sources
PubMed1997

Employing computer technology to assess visual attention in young children and adolescents with severe mental retardation.

The intent of this investigation was to establish a valid and sensitive computer measurement technique for educational assessment applications. An integral part of the investigation was to establish the similarities and differences in how prior reinforcement histories of individual stimuli affect attention to compound visual cues for young children of normal development versus adolescents with severe mental retardation, both groups having comparable mental age. A series of identical conflict compound discrimination tasks was presented to the two groups. In addition, generalization effects were investigated for both groups by presenting compounds containing some or all novel cues. The similarities and differences in performance for young children of normal development and adolescents with severe mental retardation were analyzed using multiple testing procedures. In addition to assessing stimulus control by presenting stimulus components separately following acquisition of compound discriminations, response topographies of the compound stimuli were recorded with a touch screen attached to a computer monitor screen. This study demonstrated that overselective attention did not occur only for students with severe mental retardation but also for young children of normal development if multiple tests were employed. A difference was found, however, between the two populations in the efficiency with which they shifted attention among elements of complex stimuli depending on prior conditioning histories. Presentation of compounds whose components had conflicting reinforcement histories was found to be a more sensitive assessment technique than presentation of compounds containing some or all novel components for distinguishing between the two groups. The use of multiple testing procedures was critical in preventing false conclusions from altered test performances arising from reinforcement contingencies in effect during the test.

Adolescent↗
PubMed1990

Fixed-consecutive-number performance in male and female Wistar rats.

The present experiment was designed to investigate whether or not response rate differences between male and female Wistar rats observed in many different experimental procedures could be attributed to sex differences in behavioral perseverance, as has been suggested by the results of previous experiments. Male and female Wistar rats were thus exposed to different fixed-consecutive-number schedules of reinforcement. Fixed-consecutive-number schedules require subjects to emit a specified number of responses on one (work) lever, before a response on another (food) lever results in the presentation of reinforcement. The response requirement on the work lever was manipulated in different experimental conditions. Subjects had to emit between 3 and 7, 8 and 12 or 13 and 17 responses on the work lever before a response on the food lever produced reinforcement. When subjects emitted fewer or more than the required number of responses on the work lever, a 5-s time-out period was presented. Males responded at higher rates than females during all experimental conditions; response rates of males and females increased as the response requirement on the work lever was increased. Sex differences in response efficiency were not observed, but males seemed to reach final response efficiency faster than females. Response efficiency decreased as the response requirement on the work lever was increased. Error analysis showed that both males and females made more errors by not producing enough responses on the work lever than by producing too many. However, males were more likely than females to emit more responses than the requirement on the work lever, while females were more likely than males not to produce enough responses on the work lever.

Animals↗
PubMed1997

On the relation between skilled performance of simple division and multiplication.

Are corresponding multiplication and division facts (e.g., 7 x 8, 56 divided by 7) based on common or on independent memory processes? University students received division problems alternated with multiplication problems under instructions for speeded responses. Response times were highly correlated for corresponding division and multiplication problems, and error characteristics indicated parallel retrieval structures. Specifically, division errors were constrained by the distance between the dividend and the product implied by the error, rather than by distance from the correct quotient. This suggests that division memory is organized in terms of multiplicative relationships. Multiplication errors (e.g., 7 x 9 = 56) were primed by previous division trials (56 divided by 7 = 8), but division errors were not primed by previous multiplications. The error priming results suggest that multiplication is often used at least to check division.

Adolescent↗
PubMed1984

Disruption of passive avoidance learning in the rat by electrical stimulation of the hippocampus.

The effect of electrical stimulation to discrete regions of the dorsal hippocampus on passive avoidance was examined in five experiments. Rats stepped from a brightly lit, white compartment to a dark compartment. Following footshock in the dark compartment, step-through latencies were recorded 1 min, 24 hr, and 48 hr after footshock. When given 20 step-through trials prior to footshock, dentate-stimulated animals exhibited lack of passive avoidance with particularly short latencies at 1 min, and CA1 rats showed reduced latencies compared with latencies of cortical and nonoperated controls. In Experiment 2, rats given stimulation in the same regions performed the avoidance task without prior step-through experience. All groups showed less passive avoidance than the control group in Experiment 1, and there were no significant differences between groups. With a single step-through trial before the footshock trial, longer avoidance latencies were recorded, but again groups did not differ significantly. Dentate-implanted animals, given 20 prior exposure trials but with stimulation at different stages of the task sequence, demonstrated a passive avoidance deficit at 1 min after footshock. The results are discussed in terms of the generation of expectancy that the black compartment was a safe place and the effects of brain stimulation on the expectancy, with particular reference to Vinogradova's (1975) theory of hippocampal function.

Animals↗
PubMedDate not supplied

Training transfer between card sorting and false belief understanding: helping children apply conflicting descriptions.

Two studies investigated the parallel developmental progress in theory of mind and executive control, as exemplified by correlations between the Dimensional Change Card Sorting task (DCCS; Frye, Zelazo, & Palfai, 1995) and the false-belief task. Experiment 1 with sixty 3-year-old children confirmed earlier studies (e.g., Perner & Lang, 2002), suggesting that children's problem with the DCCS lies in the redescription of stimulus objects. Experiment 2 with forty-four 3- to 4-year-olds reinforced the correlational evidence for a developmental link by showing transfer of training: False-belief training improved DCCS performance, and DCCS training significantly increased children's performance on the false-belief task. Results are discussed in relation to 5 theories explaining the existing correlational evidence.

Awareness↗
PubMedDate not supplied

7-Nitro indazole, a selective neuronal nitric oxide synthase inhibitor in vivo, impairs spatial learning in the rat.

Nitric oxide (NO) is an intercellular messenger that has been suggested to have a role in learning and memory formation. Previous studies with nonselective NO synthase inhibitors have produced contradictory results in learning experiments. However, these drugs also produced blood pressure changes, as NO is an endothelial-derived relaxing factor. A novel NO synthase inhibitor, 7-nitro indazole (7-NI), as a dose (30 mg/kg i.p.) shown previously to inhibit neuronal NO synthase by 85% without affecting blood pressure, produced amnesic effects both in a water maze and in an 8-arm radial maze. Latency as well as distance was greater in the 7-NI group in the water maze while swim speed was not affected. Latency, working memory (WM), and reference memory (RF) errors were also higher in the 7-NI group in the 8-arm maze. At the end of the second training day, these differences were no longer apparent. However, on the fourth training day, a transfer test in the water maze showed that 7-NI had produced a spatial memory deficit, reducing quadrant bias and the number of annulus crossings. Learning of a visual cue task was not affected. No difference between groups was visible in an open field test. We conclude that neuronal NO synthase activity plays a role in learning and memory formation in the rat.

Animals↗
PubMed2003

Mild procedural learning disturbances in neuroleptic-naive patients with schizophrenia.

This study investigated whether drug-naive patients with schizophrenia present procedural learning disturbances, given that this function is known to involve the striatum and that structural abnormalities of the striatum have been described in these patients. Eleven neuroleptic-free schizophrenic patients were compared with 11 healthy control subjects on a visuomotor procedural learning task (the Mirror Drawing Test). Average performance and learning rate did not differ between the two groups. However, schizophrenia patients were lower in learning smoothness (the consistency with which performance improves from trial to trial), which would indicate difficulty in benefiting from past experience to perform better on a current task. Because low smoothness has recently been found to be associated with striatal dysfunction, these results might indicate a premature dysfunction of the striatum in young drug-naive patients with schizophrenia. However, this dysfunction is not severe enough to prevent learning.

Adult↗
PubMed1999

The effects of acutely administered low dose sarin on cognitive behaviour and the electroencephalogram in the common marmoset.

Previous studies have suggested that administration of a clinically sign-free dose of sarin to non-human primates gives rise to subtle changes in brain electrical activity as measured by electroencephalography (EEG) several months following exposure. The functional significances of such changes are unclear. The present study monitored EEG by using implantable radiotelemetry, and also assessed the performance of complex behavioural tasks, in non-human primates for up to 15 months following exposure to a low dose of sarin. Baselines of EEG and behaviour were shown to be stable over several months in control animals. The doses of sarin administered caused erythrocyte cholinesterase inhibitions of 36.4% to 67.1%. Overall, no significant changes in EEG patterns were observed although there were increases in beta 2 amplitude which approached significance (p=0.07). No deleterious effects on performance were seen on the touchscreen mediated discrimination tasks presented from the Cambridge Neuropsychological Test Automated Battery (CANTAB). This study illustrates the validity of the approach employed and makes an important contribution to the investigation of the long-term effects of organophosphorous compounds.

Acetylcholinesterase↗
PubMed2004

The preparation effect in task switching: carryover of SOA.

A common finding in task-switching studies is switch preparation (commonly known as the preparation effect), in which a longer interval between task cue and trial stimulus (i.e., a longer stimulus onset asynchrony, or SOA) reduces the cost of switching to a different task. Three experiments link switch preparation to within-subjects manipulations of SOA. In Experiment 1, SOA was randomized within subjects, producing switch preparation that was more pronounced when the SOA switched from the previous trial than when the SOA repeated. In Experiment 2, SOA was blocked within subjects, producing switch preparation but not on the first block of trials. In Experiment 3, SOA was manipulated between subjects with sufficient statistical power to detect switch preparation, but the effect was absent. The results favor an encoding view of cognitive control, but show that any putative switching mechanism reacts lazily when exposed to only one SOA.

Adult↗