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Tactile agnosia. Underlying impairment and implications for normal tactile object recognition
C L Reed1, R J Caselli, M J Farah
1Department of Psychology, University of Denver, CO 80208, USA.
Brain : a Journal of Neurology
|June 1, 1996
Summary
Tactile agnosia, an impairment in recognizing objects by touch, is not due to general spatial deficits. This study shows it specifically affects tactile shape perception, worsening with complexity.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Sensory Perception
Background:
- Investigating tactile agnosia, a condition affecting object recognition via touch.
- Examining the relationship between tactile agnosia and broader spatial cognition abilities.
Observation:
- A subject with unilateral tactile agnosia demonstrated intact tactile sensation and spatial cognition.
- Testing revealed deficits specifically in high-level, somatosensory shape perception, not general spatial processing.
Findings:
- The impairment was confined to tactile shape ('what') processing, distinct from spatial ('where') information.
- Tactile object recognition deteriorated with increasing shape complexity, despite normal exploration and length encoding.
- Deficits were specific to the affected hand, with other body surfaces showing normal function.
Implications:
- Tactile shape perception can be impaired independently of general spatial abilities or tactile spatial processing.
- Suggests a specialized neural system for tactile shape analysis within the somatosensory cortex.
- Highlights the modality-specific nature of high-level perceptual deficits in tactile agnosia.