In an inefficient visual search task, when some distractors (old items) temporally precede some others (new items) the old items are excluded from the search, a phenomenon termed visual marking. This effect is considered to occur because the locations of the old items are inhibited before the new items appear. The present study used a probe-detection task to examine whether this inhibition occurs selectively at the locations of task-relevant old items or those of task-relevant and task-irrelevant old items. The participants searched for a target, or detected a probe, that appeared after the new items. The results revealed that the probe reaction times at locations of task-relevant old items were longer than those at the locations occupied by task-irrelevant old items and a blank region where no items had been presented. However, a task-relevancy effect was not obtained when the target did not appear at the locations of task-irrelevant old items. We conclude that the inhibitory template for visual marking represents the locations of task-relevant old items selectively.
The present study examined whether the spin of a horizontally translating target in an animation movie modulates the magnitude of forward displacement of a remembered final position of the target. The rotation of an axis bar corresponding to the diameter of a circular target represented the target's spin. There were three spin conditions: forward, backward, and without spin. The observers had to manually localize the vanished position of the target without eye movements. Experiment 1 showed that forward displacement was larger in the forward spin condition than in the backward spin condition and also confirmed that this modulation of forward displacement by object spin was not due to observers' eye movements. Experiment 2 demonstrated that the modulation of forward displacement was not observed when horizontal translational motion was removed from the stimuli, suggesting that the interaction between the target's spin and the horizontal translational motion is critical. These results indicate that implicit friction due to object spin modulates forward displacement without the involvement of eye movements.
In general, a visual search for a target that is determined by the conjunction of features becomes inefficient (Treisman & Gelade, 1980). However, Watson and Humphreys (1997) discovered that a search became efficient when half of the distracters were previewed (preview effect). Moreover, Braithwaite, Humphreys, and Hodsoll (2003) found that the preview effect was weakened when the previewed stimuli and the target had the same color (negative carryover). They suggested that there was inhibition which was based on the features of the previewed stimuli, and that the inhibition was generalized to the target. We conducted two experiments to examine whether there is category-based inhibition. The preview effect was observed in both experiments. Also, there was a category-based negative carryover when the target category could not be anticipated (Experiment 2) but with anticipation this phenomenon was eliminated (Experiment 1). The results suggest that, depending on the task setting, category-based negative carryover can occur. However there is a possibility that the effect could be observed with any other factor, rather than the generalization of inhibition.
As previous studies have shown, amodally perceived figures can be completed by using two different rules: smooth continuity and symmetry. Markovich (2002) showed that amodal perception is affected by stimulus orientation. In the present study, we investigated further how amodal perception is affected by stimulus orientation and by the shape of the occluding and occluded patterns. The results demonstrated that: (1) a "symmetrical amodal figure" tends to appear in a vertical axis rather than a horizontal or diagonal axis; (2) depending on the pattern orientation, an amodal figure can be induced by the shape of the occluder. This means that we perceive an amodal figure not only by smooth continuity or symmetry, but also by the contextual condition and frame of reference.
We examined how the perceived simultaneity and temporal order of two visual stimuli depends upon the depth position of the stimuli specified by binocular disparity cue. When two stimuli were presented simultaneously at different depth positions in front of or around a fixation point, the observer perceived the more distance stimulus appeared before the nearer stimulus (Experiment 1). This illusory temporal order was found only for sudden stimulus presentation (Experiment 2). Similar tendency was found in the processing for motion-in-depth (Experiment 3). For the involuntary attention, which was caused by sudden presentation of a preceding stimulus, the effect of the preceding stimulus, which was presented in the depth space nearer than the fixation point, was larger than that of the stimulus, which was presented in the more distant space than the fixation point (Experiment 4). These results suggest that a common processing, which are related to the detection of the motion-in-depth underlies these bias in terms of the stimulus depth position, and therefore, that, in order to understand the basis of the perception of the simultaneity and temporal order, we have to clarify the temporal bias in the processing which are involved in conducting the experimental task.
If time-marking events constitute a temporal pattern as in music, they are often perceived as being played at a particular tempo, lending a sense of "rhythm keeping." The present study examined how actual event timing in drum phrases would affect the formation of this impression. A sense of rhythm keeping was derived even with physically non-isochronous patterns if some beats were subdivided by markers. This tolerance for timing deviations varied along the base tempo of the phrases, being only partially consistent with the prediction from the conventional illusion of a divided time interval. These results were discussed in terms of the processing of time intervals and sequences of them.
We unconsciously sense passage of time, and generate regular recurrent trains of movements like vocalization, walking or respiration, without an effort. This ability of temporal perception must be traced down to the loci in the human brain. Although still premature, the research on this line is indicating that at least three distinct modes are present to sense the time passage in the brain. Very long time, like an event in childhood is dealt with mechanisms involving memory consolidation, retrieval and association. The Hippocampus and orbitofrontal cortex are implicated in this mode of time perception. Time of the day sense and its underlying clock has been well delineated recently by the molecular biological technique. The circadian pacemaker is located in the Suprachiasmatic nucleus of the hypothalamus and driven by the feedback loop at the gene and protein level. Third mode of time sensing is the generation of short interval of time. These second to minute rhythms are in part taken care of in the nucleus of the basal forebrain such as the Striatum and Caudate nucleus.