Facilitation and inhibition in the spatiotemporal template for detecting target ring


Using the classification image technique (Ahumada, 1996), this study investigated the nature of spatiotemporal facilitatory and inhibitory templates when detecting a target ring. The stimulus consisted of fifteen temporal frames of five spatial elements: one-center disk and four-surrounding concentric rings. When a target was present, the middle brighter ring than the screen background always served as the target, and the rest of the elements were darker than the background. Random luminance noises were changed on every stimulus frame. On a non-target trial the non-target pattern was presented across all 15 frames. On a target trial the target pattern was presented at the middle three temporal frames. Results showed a transient facilitatory response at the target location around the target presentation and an inhibitory response from the outer elements even after the target’s actual presentation. These results suggest that spatiotemporal templates are not simple copies of the spatiotemporal target pattern.

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