title: Temporal cues contribute to tactile perception of roughness.
abstract: Optimal perception of surface roughness requires lateral movement between skin and surface, suggesting the importance of temporal cues. The roughness of periodic gratings is affected by changing either inter-element spacing (groove width, G) or element width (ridge width, R). Peripheral neural responses to gratings depend quantitatively on a spatial variable, G, and a temporal variable, grating temporal frequency (F(t)), with changes in R acting indirectly through concomitant changes in F(t). We investigated, psychophysically, the contribution of temporal cues to human tactile perception of roughness, using gratings varying in either R or G. Gratings were scanned across the immobile fingerpad with controlled movement speed (S) and contact force. In one experiment, we found that roughness magnitude estimates depended on both G and F(t). In a second experiment, discrimination of the roughness of gratings varying in either R or G was affected by manipulating F(t). Overall, the effect of G on roughness judgments was much stronger than that of F(t), probably explaining why many previous studies using surfaces that varied only in inter-element spacing led to the conclusion that temporal factors play no role in roughness perception. However, the perceived roughness of R-varying gratings was determined by F(t) and not spatial variables. Roughness judgments were influenced by G and F(t) in a manner entirely consistent with predicted afferent response rates. Thus perceived roughness, like peripheral afferent responses, depends in part on temporal variables.
authors: Department of Neurology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
authors: C J
authors: CJ
authors: Cascio
authors: K
authors: K
authors: Sathian
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D003463:Cues; D004056:Differential Threshold / Q000502:physiology; D004193:Discrimination Learning / Q000502:physiology*; D005260:Female; D005385:Fingers / Q000294:innervation / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008959:Models, Neurological; D010507:Periodicity; D010812:Physical Stimulation / Q000295:instrumentation / Q000379:methods; D012684:Sensory Thresholds / Q000502:physiology; D013499:Surface Properties; D013997:Time Factors; D014110:Touch / Q000502:physiology*