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Face repetition effects in implicit and explicit memory tests as measured by fMRI.
R N A Henson1, T Shallice, M L Gorno-Tempini
1Wellcome Department of Cognitive Neurology, University College London, 17 Queen Square, London WC1N 3AR, UK. r.henson@ucl.ac.uk
Cerebral Cortex (New York, N.Y. : 1991)
|December 12, 2001
Summary
Repetition suppression, a decrease in brain response to repeated stimuli, was only observed in implicit tasks, not explicit ones. This suggests it is not an automatic result of perceptual processing.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Neuroimaging
Background:
- Neuroimaging studies suggest repeated stimulus processing leads to decreased neural responses, known as repetition suppression.
- This effect is thought to reflect neural efficiency but its automaticity is debated.
Purpose of the Study:
- To investigate whether repetition suppression is an automatic neural process.
- To examine the influence of task type (implicit vs. explicit) on repetition suppression during face perception.
Main Methods:
- Functional magnetic resonance imaging (fMRI) was used to scan volunteers.
- Participants performed two tasks: implicit fame-judgements and explicit recognition judgements on repeated presentations of famous and unfamiliar faces.
Main Results:
- Repetition suppression was observed only during the implicit fame-judgement task.
- Specifically, suppression occurred in the right lateral fusiform region for famous faces and the left inferior occipital region for both famous and unfamiliar faces.
- No repetition suppression was found during the explicit recognition task.
Conclusions:
- Repetition suppression is not an automatic consequence of repeated perceptual processing.
- Task demands and the nature of cognitive processing significantly modulate neural responses to repeated stimuli.