We investigated the combined effects of perceptual grouping cues (proximity and contour closure/proximity and orientation similarity) on object representation, using motion-induced blindness, a phenomenon in which salient visual stimuli perceptually disappear when surrounded by moving patterns. We presented as visual targets two stimuli in which a solid square was embedded in an outlined square. Participants reported whether the targets disappeared independently or simultaneously. The results showed that a relatively high proximity cue (with a 0.2-deg separation between the targets) modulated the perceptions of the independent or simultaneous disappearances of targets, regardless of other grouping cues. The contour closure cue modulated these disappearances in the 0.4- to 0.8-deg separations. Finally, the orientation similarity cue began to modulate these disappearances in the 0.6- to 0.8-deg separations. We suggest that the separation between the visual stimuli modulates the combined effects of perceptual grouping cues on complete object representation.
Affective meanings aroused by various objects, such as paintings, melodies, or words, can be quantified by the semantic differential (SD) technique (Osgood, Suci, & Tannenbaum, 1957). In this technique, three main factors ("Evaluation," "Activity," and "Potency") have been consistently extracted from factor analyses of participants' subjective ratings of various objects using bipolar scales of adjective pairs. In the present study, we investigated brain activity during SD ratings of linedrawing stimuli using functional magnetic resonance imaging (fMRI). We compared brain activity among the three main factors underlying affective meanings. The overall results showed that Evaluation, Activity, and Potency produced brain activities in the inferior frontal gyrus, the superior temporal gyrus, and the superior frontal gyrus, respectively. These findings suggest that the psychological structures underlying affective meanings are distributed in specific areas of the brain.
A startle reflex to a startle pulse is inhibited when preceded by a prestimulus. We introduced a key-press action (self-action) or an 85 dB noise burst as a prestimulus, followed by a 115 dB noise burst as a startle pulse. We manipulated temporal offsets between the prestimulus and the startle pulse from 30-1,500 ms to examine whether self-action modulates the startle reflex and the temporal properties of the modulatory effect. We assessed eyeblink reflexes by electromyography. Both prestimuli decreased reflexes compared to pulse-alone trials. Moreover, the temporal windows of inhibition were different between the types of prestimuli. A faster maximal inhibition and narrower temporal window in self-action trials suggest that preceding self-action inhibits the startle reflex and allows prediction of the coming pulse in different ways from auditory prestimuli.
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