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At least 397 records · Page 22Linked to original sources
PubMed1992

Monkeys (Macaca fascicularis) with rhinal cortex ablations succeed in object discrimination learning despite 24-hr intertrial intervals and fail at matching to sample despite double sample presentations.

Six cynomolgus monkeys (Macaca fascicularis) learned preoperatively a set of 10 concurrent object discriminations with 24-hr intertrial intervals. Three then had the rhinal cortex removed bilaterally, whereas the other 3 remained as unoperated controls. The animals with ablations were impaired in reacquiring the preoperatively acquired set but subsequently learned without any impairment a new set of 10 discriminations that was presented in the same way. The monkeys with rhinal cortex ablations then failed to learn delayed matching to sample, with double sample presentations, in 510 trials, whereas the control animals learned this task in 270 trials on average. The results add to existing evidence that rhinal cortex ablation produces a severe impairment in visual short-term recognition memory and show for the first time that this impairment is accompanied by normal long-term discrimination learning ability.

Animals↗
PubMed1989

Unilateral periarcuate and posterior parietal lesions impair conditional position discrimination learning in the monkey.

Monkeys were trained on a conditional position discrimination in which the conditional cue was a light blinking at two distinct rates and the discriminanda (illuminated buttons) appeared in varying symmetrical positions of eccentricity. Unilateral arcuate, posterior parietal, or principal sulcus lesions were performed at criterion. The monkeys were tested to recovery when a homologous lesion was made contralaterally. The first of two analyses examined a period of 4 weeks following each lesion; the unit of analysis was lesions. The arcuate and parietal lesions produced impairments on both widely eccentric and central discriminanda locations; initially, virtually all responses were deflected to the ipsilateral side. There was significant improvement after the arcuate and parietal lesions from weeks 1 to 4. An analysis of total trials to criterion showed major deficits from the second arcuate and parietal lesions, with the arcuate lesion impairment being particularly severe. These results establish that a spatial concept of left vs right is seriously deranged by unilateral lesions of cortical association areas involved in spatial orientation and discrimination.

Animals↗
PubMed1983

Two-year follow-up study of discrimination learning by mentally retarded children.

Mentally retarded children were taught to discriminate the dimensions of a visual display using a matching-to-sample procedure that provided full verbal feedback of the reasons for successes and failures. A control group attempted the matching procedure but received no feedback. The trained subjects exhibited marked superiority in intradimensional transfer. Two years later, the trained subjects continued their advantage but to a lesser degree.

Adolescent↗
PubMed2002

Visual discrimination learning and strategy behavior in the fat-tailed dunnart (Sminthopsis crassicaudata).

Fat-tailed dunnarts (Sminthopsis crassicaudata) were trained on visual discrimination learning-set, reversal-set, and spatial delayed-alternation tasks. The learning set involved 36 2-way black-and-white pattern discriminations and 5 probe reversals. Ten reversals of a black-and-white pattern discrimination were followed by 5 novel tasks. Spatial alternation was tested at delays up to 20 s. Learning-set and reversal-set formation, including 1-trial learning and spontaneous transfer from learning set to reversals and vice versa, was found. Learning-set-experienced dunnarts showed no retention of previously learned tasks 1 week after testing but demonstrated consistently high Trial 2 performance, indicating the retention of a response strategy. Delayed-alternation tasks were learned up to 10-s delays. These results provide the first evidence of a visually guided "win-stay, lose-shift" strategy in a marsupial.

Analysis of Variance↗
PubMed2000

Individual vocal recognition and the effect of partial lesions to HVc on discrimination, learning, and categorization of conspecific song in adult songbirds.

Among songbirds, the capacity to associate particular songs with particular singers (i.e., vocal recognition) forms the cognitive basis for more complex communication behaviors such as female choice and territoriality. In the present study, we combine operant conditioning techniques and excitotoxic lesions to the forebrain nucleus HVc to examine the role of this region in the discrimination, associative learning, and categorization of conspecific song. We trained adult male and female European starlings, Sturnus vulgaris, to recognize simultaneously the songs of several conspecific males. Then, using a series of transfer procedures, we demonstrate that correct recognition does not generalize to song bouts containing novel motifs from familiar singers. This suggests that starlings do not make use of individually invariant source or filter characteristics for vocal recognition. We then lesioned a portion of HVc bilaterally with ibotenic acid, and exposed the birds to a series of manipulations testing the discrimination, associative learning, and categorization of conspecific song. The lesions attenuated song production among males, but retention of the basic recognition task (i.e., maintenance of the discrimination) was unaffected. However, when the response contingencies were reversed-as a test of associative learning independent of discrimination-the initial performance and subsequent learning rate were negatively correlated with the size of the HVc lesions. This suggests that HVc plays a role in the formation of associations between a song and some referent. The results of this study are discussed in light of earlier claims regarding the role of HVc in the perceptual processing of conspecific song.

Acoustic Stimulation↗
PubMed2003

Relational discrimination learning between amplitude-modulated sounds in the rat.

We studied the cue used by rats to discriminate between amplitude-modulated (AM) sounds. Water-deprived rats were exposed to two sounds, and licking a spout during the presentation of one of the two (S+) was rewarded with water, while licking during the other (S-) was not. The AM depth was 100, 60 or 20%. Rats were trained to discriminate between 100 and 60% AM sounds over 2 consecutive days. On the next day, the performance in discriminating between 60 and 20% AM sounds was evaluated. Of the four possible combinations of stimuli, a good performance was observed only when the relationship between S+ and S- regarding the AM depth was kept constant throughout the experiments, indicating that the relationship regarding the AM depth was the cue used by the rats for the discrimination.

Acoustic Stimulation↗
PubMed2005

Acquired distinctiveness and equivalence in human discrimination learning: evidence for an attentional process.

In a first stage of training, participants learned to associate four visual cues (two different colors and two different shapes) with verbal labels. For Group S, one label was applied to both colors and another to both shapes; for Group D, one label was applied to one color and one shape, and the other label to the other cues. When subsequently required to learn a task in which a given motor response was required to one of the colors and one of the shapes, and a different response to the other color and the other shape, Group D learned more readily than Group S. The task was designed so that the associations formed during the first stage of training could not generate differential transfer to the second stage. The results are consistent, however, with the proposal that training in which similar cues are followed by different outcomes will engage a learning process that boosts the attention paid to features that distinguish these cues.

Association Learning↗
PubMed1999

Effects of similarity and experience on discrimination learning: a nonassociative connectionist model of perceptual learning.

This article describes a novel connectionist model of perceptual learning (PL) that provides a mechanism for nonassociative differentiation (J. J. Gibson & E. J. Gibson, 1955). The model begins with the assumption that 2 processes--1 that decreases associability and 1 that increases discriminability--operate during preexposure (S. Channell & G. Hall, 1981). In contrast to other models (e.g., I. P. L. McLaren, H. Kaye, & N. J. Mackintosh, 1989), in the current model the mechanisms for these processes are compatible with a configural model of associative learning. A set of simulations demonstrates that the present model can account for critical PL phenomena such as exposure learning and effects of similarity on discrimination. It is also shown that the model can explain the paradoxical result that preexposure to stimuli can either facilitate or impair subsequent discrimination learning. Predictions made by the model are discussed in relation to extant theories of PL.

Animals↗