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Biomedical subjects

P Perruchet

Publications and source records attributed to P Perruchet.

11 recordsLinked to original sources
PubMed1995

Conceptual implicit memory: a developmental study.

The widely accepted standpoint that implicit memory emerges earlier in development than explicit memory, and is more stable from childhood to adult age, is based on experimental data essentially collected in perceptual tasks. The present study was aimed at investigating whether these findings still hold when a more conceptual task is used. We compared the performance of children at two age levels (2nd and 4th grades) on a category-exemplar generation task. Results showed that performances of the two groups were comparable when the target items were typical of their categories, as in Experiment 2, and for a subset of the items in Experiment 1. However, the older children outperformed the younger children in Experiment 1 when the items selected were atypical of their categories. Interpretations of these findings are discussed.

Child↗
PubMed1994

Ventilatory conditioning by self-stimulation in rats: a pilot study.

This article describes an experimental attempt to condition breathing pattern in rats. In this experiment, a freely moving rat was first rewarded by an electrical stimulation of the medial forebrain bundle whenever inspiratory duration (TI) exceeded 300 ms. A bidirectional control was then used: TIs longer than 400 ms were rewarded, and then TIs shorter than 300 ms were rewarded. The frequency of TIs longer than 300 ms increased when this event was rewarded, further increased when TIs above 400 ms were rewarded, and decreased during reversal conditioning (TI < 300 ms). At the beginning of the experiment, stimulation caused increased arousal and motor activity, but after prolonged conditioning, the brain stimulation was associated with quiet wakefulness. Although the general procedure appears to be well-suited to the experimental study of voluntary breathing, some possible improvements are suggested for further, more extensive investigations.

Animals↗
PubMed1994

The dissociation of explicit and implicit memory in depressed patients.

Twenty-three in-patients fulfilling DSM-III-R criteria for major depressive disorder were submitted to a standard cued recall test, and to a word-stem completion test devised to assess the effect of the initial presentation without the explicit retrieval of the words being necessary. Results show that depressed patients are impaired on the cued recall task in comparison with controls matched for sex, age, and educational level. However, the two groups do not differ in the word-stem completion task. This dissociation between explicit and implicit expressions of memory disappeared when patients recovered, although they were still hospitalized and under psychotropic medication. These results are examined in the light of the distinction between effortful and automatic processes.

Adult↗
PubMed1992

Conscious knowledge and changes in performance in sequence learning: evidence against dissociation.

Two experiments examined the relation between explicit knowledge and motor performance on the serial reaction time task developed by Nissen and Bullemer (1987). Tests of free recall and recognition of sequence components revealed that reliable explicit knowledge was acquired after an amount of practice that was hardly sufficient to improve mean motor performance. In addition, reaction time improvement was limited to the ending trials of the 3- and 4-trial sequence components that Ss recalled or recognized. These results were replicated in Experiment 3, in which Ss were trained under attentional distraction in the task developed by Cohen, Ivry, and Keele (1990). Overall, these findings undermine the most direct experimental support for the widespread view that conscious knowledge and performance in sequence-learning tasks tap 2 independent knowledge bases in normal Ss.

Adult↗
PubMed1991

Effect of practice on the voluntary control of a learned breathing pattern.

Changes in orientation of attention and ventilatory data were examined in three normal volunteers who practiced a learned ventilatory pattern over eight training sessions. The breathing task was a voluntary increase of inspiratory duration up to a given target with the aid of informative feedback on this variable. The orientation of attention was investigated through reaction time (RT) to auditory stimuli presented at different points in inspiration and expiration, during either automatic or voluntary control of breathing. Findings show that RTs are longer during voluntary than automatic breathing throughout the experiment, and that they decrease across sessions in both conditions. In the first sessions, RTs were longer during expiration than inspiration but this difference cancels out in the last sessions. The results are discussed in terms of attentional demands of control of breathing, automatization, and the connection between automatic and voluntary control of breathing. This work shows that after eight practice sessions, the orientation of attention displays significant changes; however, the control of breathing remains attention demanding.

Animals↗
PubMed1991

Assessing attentional control of breathing by reaction time.

The reaction time (RT) to an auditory stimulus was measured in 27 subjects during spontaneous breathing and during controlled breathing, which consisted of maintaining a set inspiratory duration. During spontaneous breathing, reaction times were unrelated to the time the stimulus was delivered during the breathing cycle. During controlled breathing, reaction times were longer than during spontaneous breathing. Peak reaction times were observed at the transition from inspiration to expiration. After the end of controlled breathing, reaction times gradually became shorter until they reached their initial level. The findings are discussed in terms of varying allocation of attentional resources to breathing. It is argued that probe RT methodology provides a suitable means for investigating attentional control of breathing.

Adult↗
PubMed1991

Classical conditioning of ventilatory responses in humans.

A classical conditioning experiment, in which an auditory stimulus was paired with a hypoxic stimulus, was carried out on 34 normal subjects assigned to two groups (experimental and control). Each subject took part in one session divided into two phases, acquisition and test. In the acquisition phase, eight hypoxic and eight auditory stimuli were paired in the experimental group and unpaired in the control group. In the test phase, which was identical for the two groups, the hypoxic stimuli were suppressed and three purely auditory stimuli were presented. Significant differences between the two groups in ventilatory response to these auditory stimuli provided evidence for conditioning. In the control group, no significant changes were elicited by the auditory stimuli, whereas a conditioned increase in total cycle duration was observed in the experimental group. The conditioned response closely resembled the first component of the hypoxic response. Analysis of the pattern of the conditioned response, along with postexperimental interviews, strongly suggests that this response was not mediated by volitional factors.

Acoustic Stimulation↗
PubMed1989

Correlational analyses of explicit and implicit memory performance.

Sixty-four subjects were administered two tests of explicit memory (selective recall and recognition) and four tests of implicit memory (identification in a perceptual clarification procedure, word-fragment completion, tachistoscopic identification, and anagram solution). Each test drew on a different subset of a long list of previously displayed words. Although the four implicit memory tests showed sizable priming effects, correlational and factor analyses showed striking dissociations. On the one hand, performance on the perceptual clarification procedure and word-completion tests were related to one another, as well as to recall and recognition. On the other hand, performance on tachistoscopic identification and anagram solution were related to one another, but not to the measures for the other tasks. A framework is proposed to reconcile these new results with current knowledge on the explicit/implicit memory distinction, based in particular on studies of amnesic subjects. It is argued that a small number of tasks, especially tachistoscopic identification, may serve as relatively uncontaminated and ubiquitous indicators of implicit memory. However, explicit remembering could affect performance in so-called implicit memory tasks that allow for a strategy of controlled selection of candidate responses from accumulating cues, in experimental conditions that make the explicit remembering of relevant events possible.

Adult↗
PubMedDate not supplied

A pitfall for the expectancy theory of human eyelid conditioning.

Two simple eyeblink conditioning experiments with random intermittent reinforcement schedules were performed. In Experiment 1, subjects had to rate their expectancy for an unconditioned stimulus (US) on a seven-level scale prior to each trial. As anticipated, expectancy for US increased with a successive conditioned stimulus (CS) alone, and decreased with successive CS-US pairings. However, Experiments 1 and 2 showed that the frequency of eyeblink conditioned responses (CRs) evolved in a direction opposite to that of expectancy changes: CRs increased, whereas expectancy for US decreased, and vice versa. The possible effect of sensitization on eyeblink response was ruled out by the lack of a run effect in an unpaired control group in Experiment 2. These results tend to disconfirm the expectancy theory of conditioning. Although they were explicitly predicted by the conventional "strength" theory of conditioning, an alternative interpretation is proposed within a cognitive framework.

Adult↗