Takayuki Osugi

The spatial distribution of inhibition in preview search.

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 said 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 only at the precise locations of old items or at and around the locations of old items. We also investigated the effect of inhibition overreaching boundaries to encompass neighboring regions. Participants searched for a target or detected a probe that appeared after the new items appeared. The results revealed that the probe reaction times at locations inside grouped regions were longer than those at a blank region where no items had been presented and were comparable to those at a location occupied by old items. Probe detection was not delayed when the probe was presented near but external to the external boundary of the grouped regions. The overreaching effect was obtained before and after the new items appeared. We conclude that the inhibitory template for visual marking represents clusters of old items for at least 200 ms before the onset of new items, and that this spatial schema is preserved until at least 200 ms after the onset of new items.

Visual marking survives graphical change if meaning is retained

National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan When some distractors (old items) appear before others (new items) in an inefficient visual search task, the old items are excluded from the search (visual marking). Previous studies have shown that shape changes of static old items are sufficient to eliminate this effect when global luminance is maintained, suggesting that shape identity must be maintained for successful visual marking. It was unclear whether the change in meaning or shape was critical, because these changes were confounded in previous studies. The present study examined whether consistency in the semantic or the graphical identity of old items is critical for visual marking by introducing shape change in the absence of meaning change. The results indicated that visual marking survived graphical changes in old items as long as their meaning was maintained, suggesting that the memory template underlying visual marking represents the semantic identity of old items.

Previewing distractors reduces efficiency of visual processing at previewed locations.

Visual marking refers to the phenomenon in which old items in a visual search are excluded from the search when new items appear in the visual field. Visual marking may result from inhibition of irrelevant information at the location of old items before new items appear. Moreover, sensitivity to increments in contrast at the old locations has been shown to be lower than that to increments at the new locations. We used equivalent noise analysis to examine whether the reduction in sensitivity is the result of an increase in internal noise or a decrease in calculation efficiency. Following a search in which reaction time was measured, participants were asked to indicate whether a Gaussian luminance blob was present. Parameters estimated from the threshold-versus-noise contrast function indicated that calculation efficiency at old locations was lower than that at new locations, and internal noise did not increase at old locations but rather decreased slightly. Thus, the reduction in sensitivity at old locations is attributable a decrease in calculation efficiency. These data suggest that an inhibitory template for visual marking may benefit visual search by diverting limited attentional resources, such as time and resolution, away from previewed locations and reserving them for the target search.

Onset of background dynamic noise attenuates preview benefit in inefficient visual search

When certain distractors (old items) appear before others (new items) during an inefficient visual search task, observers exclude the old items from the search (preview benefit), possibly because their locations are deprioritized relative to the locations of the new items. We examined whether participants were able to ignore task-irrelevant changes in a scene (i.e., the onset of repetitive changes, continual repetitive changes, and the cessation of repetitive changes in the background), while performing a preview search task. The results indicated that, when the noise continually changed position throughout each trial, or when dynamic noise was changed to static noise simultaneous with the appearance of the search display, the preview benefit remained. In contrast, when the static background noise was changed to dynamic background noise, simultaneous with the appearance of the search display, this task-irrelevant background event abolished the preview benefit on search efficiency. Therefore, we conclude that the onset of task-irrelevant repetitive changes in the background disrupts the process of inhibitory marking of old items.

Effects of bowing on perception of attractiveness

Bowing is a greeting behavior. The present study examined the modulation effect of bowing on perception of attractiveness. In each trial, a portrait digitized from university yearbooks was presented on a computer screen. The portrait was mildly tilted toward participants to simulate a greeting bow (25-degree angle). Participants evaluated the subjective attractiveness of the face using a visual analog scale (0-100). The mean attractiveness judgment of the bowing portrait was significantly higher relative to that of the bending-backward or standing-still control conditions (Experiment 1). Additional control experiments revealed that alternative accounts relying on apparent spatial proximity and physical characteristics could not solely explain the effect of bowing (Experiment 2) and indicated that the effect was specific to objects perceived as faces (Experiment 3). Furthermore, observers’ in-return bowing behavior did not reduce the bowing effect (Experiment 4), and bowing motion increased the ratings of subjective politeness and submissiveness (Experiment 5). Finally, tilting the 3D faces elicited the same effect from observers as did tilting the still photos (Experiment 6). These results suggest that a tilting motion of portraits (or images of face-like objects) mimicking bowing enhances perceived attractiveness, at least as measured in a culture familiar with greeting by bowing.

Attentional Capture to a Singleton Distractor Degrades Visual Marking in Visual Search

Visual search is easier after observing some distractors in advance; it is as if the previewed distractors were excluded from the search. This effect is referred to as the preview benefit, and a memory template that visually marks the old locations of the distractors is thought to help in prioritizing the locations of newly presented items. One remaining question is whether the presence of a conspicuous item during the sequential shift of attention within the new items reduces this preview benefit. To address this issue, we combined the above preview search and a conventional visual search paradigm using a singleton distractor and examined whether the search performance was affected by the presence of the singleton. The results showed that the slope of reaction time as a function of set size became steeper in the presence of a singleton, indicating that the singleton distractor reduced the preview benefit. Furthermore, this degradation effect was positively correlated with the degree of conventional attentional capture to a singleton measured in a separate experiment with simultaneous search. These findings suggest that the mechanism of visual marking shares common attentional resources with the search process.

Inhibition of return shortens perceived duration of a brief visual event

We investigated the influence of attentional inhibition on the perceived duration of a brief visual event. Although attentional capture by an exogenous cue is known to prolong the perceived duration of an attended visual event, it remains unclear whether time perception is also affected by subsequent attentional inhibition at the location previously cued by an exogenous cue, an attentional phenomenon known as inhibition of return. In this study, we combined spatial cuing and duration judgment. After one second from the appearance of an uninformative peripheral cue either to the left or to the right, a target appeared at a cued side in one-third of the trials, which indeed yielded inhibition of return, and at the opposite side in another one-third of the trials. In the remaining trials, a cue appeared at a central box and one second later, a target appeared at either the left or right side. The target at the previously cued location was perceived to last shorter than the target presented at the opposite location, and shorter than the target presented after the central cue presentation. Therefore, attentional inhibition produced by a classical paradigm of inhibition of return decreased the perceived duration of a brief visual event.

Effects of Head Nodding and Shaking Motions on Perceptions of Likeability and Approachability

It has been demonstrated that bowing motion of computer-generated female three-dimensional figures enhanced perceived attractiveness. Given that nodding and shaking head motions are used as communicative signals, such as signals of approval (and denial), these motions could be expected to modulate perceived trait impressions of model faces. We used movie clips of the nodding and shaking head motions of computer-generated figures and examined the modulation effects of these motions on perceived trait impressions (i.e., attractiveness, likability, and approachability). The results showed that the nodding head motion significantly increased ratings of subjective likability and approachability relative to those of the shaking or control conditions, whereas the shaking motion did not influence the ratings. Furthermore, it was shown that a nodding head motion of the computer-generated models primarily increased likability attributable to personality traits, rather than to physical appearance. We concluded that head nodding motion is treated as information regarding approach-related motivations and enhances perceived likeability.

A Drastic Change in Background Luminance or Motion Degrades the Preview Benefit

When some distractors (old items) precede some others (new items) in an inefficient visual search task, the search is restricted to new items, and yields a phenomenon termed the preview benefit. It has recently been demonstrated that, in this preview search task, the onset of repetitive changes in the background disrupts the preview benefit, whereas a single transient change in the background does not. In the present study, we explored this effect with dynamic background changes occurring in the context of realistic scenes, to examine the robustness and usefulness of visual marking. We examined whether preview benefit in a preview search task survived through task-irrelevant changes in the scene, namely a luminance change and the initiation of coherent motion, both occurring in the background. Luminance change of the background disrupted preview benefit if it was synchronized with the onset of the search display. Furthermore, although the presence of coherent background motion per se did not affect preview benefit, its synchronized initiation with the onset of the search display did disrupt preview benefit if the motion speed was sufficiently high. These results suggest that visual marking can be destroyed by a transient event in the scene if that event is sufficiently drastic.