The Time Course Of Cognitive Processing:Object’s Different Dimensional Properties

The cognitive representation of an object includes not only its surface properties, representing perceptual information about the object, but also its name properties, representing semantic information about the object. Previous research has investigated an object’s perceptual properties and semantic property, but little work has been done on the neural mechanism of perceptual properties and name properties presented together. The aim of these studies were to explore the time course of cognitive processing of an object’s different dimensional properties, using event-related potentials (ERPs) with high temporal resolution in two experimental studies.In study 1, Fifteen undergraduate participants engaged in a "same or different" judgment task involving irregular forms under four different conditions:shape-changed (SC), color-changed (CC), name-changed (NC) and identical condition (IC). The results showed that P1 component, P2 component and N2 component were all evoked in three of conditions, including SC condition, CC condition and NC condition. SC condition elicited an enhanced P1 component than CC and NC condition at an early stage, while P2 component and N2 component were elicited most strongly in the CC condition and a clear N400 component was elicited in NC condition. These findings suggested some specificity in processing each property, with shape processed earlier than color and name, but color-processing responses stronger than shape and name at perceptual level.In study 2, eighteen undergraduate participants engaged in a "same or different" judgment task involving irregular forms under three different conditions:shape-changed (SC), color-changed (CC), and identical condition (IC). The study was to explore whether the specificity of shape property processed in study 1 was related with the object’s name property presented together. The results showed that P1 and N2 components were evoked in SC and CC condition when object’s name property was not presented, while the averaged amplitudes of P1 component were not significantly different between SC and CC condition. The averaged amplitudes of N2 component were stronger in CC condition than in SC condition. The results suggested that the specificity of processing shape property was related with the name property presented, while the color property processing was not changed with the name presented.