松下 戦具

Mental rotation is known to be mediated by sensorimotor processes. To deepen our understanding of the role of somatosensory inputs in mental rotation, we investigated the effects of holding weight by the hands on mental rotation performance. In an experiment, 22 male and 22 female students performed a chronometric mental rotation task while holding either light or heavy bags in both hands. Results showed that females holding heavy bags were quicker and more accurate at mental rotation than females holding light bags, as evidenced by shallower slopes for response times (RTs) and error rates. In contrast, males showed no such heavy-bag-induced improvement. Unlike slopes, intercepts for RTs and error rates were equivalent regardless of sex and bag weight. Consistent with previous research on embodied cognition, the present findings demonstrated the facilitatory role of somatosensory cues by weight in mental rotation and suggested sex differences in embodied processes in mental rotation.

Whereas geometric illusions in human faces have been reported by several studies, illusions of color or lightness in faces have seldom been explored. Here, we psychophysically investigated whether lip color influences facial skin's perceived lightness. Results of Experiment 1 demonstrated that redder lips lightened and darker lips darkened the perceived complexion. These lightness or darkness inducing effects differ from the classical illusion of lightness contrast in nonface objects for two reasons. First, illusory effects are more assimilative than contrastive. Second, the inducing area (i.e., lips) is much smaller than the influenced area (facial skin). Experiment 2 showed that the assimilative lightness induction was caused by holistic processing of faces. This is the first study to scientifically substantiate the claim of cosmetics manufacturers and makeup artists that lip colors can alter perceived facial skin color. Implications for face perception, lightness illusion, and perceptual effects of cosmetics are discussed.

GROOVE IS A PLEASANT FEELING THAT COMPELS people to move their bodies along with music. In the past, there was some consensus among both musicians and researchers that the main factor in inducing this feeling is onset asynchrony of sounds. However, recent studies have asserted that no-asynchrony is the condition that will obtain the highest groove. The current study examined whether no-asynchrony exclusively elicits the highest groove. In Experiment 1, we measured the groove increment of a backbeat drum pattern as a function of the asynchronies between bass guitar and hi-hat cymbal sounds. Upon evaluation, the scores of no conditions exceeded those of the synchronous condition. However, the condition with slight bass guitar precedence over the hi-hat achieved an approximately equal score to the condition with complete synchrony, and that score was higher than the ones achieved with bass delay. In Experiment 2, we measured the participants' sensitivities to timing discrimination. The results confirmed that the amount of bass precedence in Experiment 1 was perceptible to the listeners. These findings suggest that complete synchronization is not always the best condition to achieve groove and that listeners prefer perceivable asynchronies in some cases.

Does an assimilative illusion like the Delboeuf illusion occur in the human face? We investigated factors that might influence the perceived size of the eyes in a realistic face. Experiment 1 manipulated the position of the eyebrows (high or low), the presence/absence of eye shadow, and the viewing distance (0.6 m or 5 m), then measured the perceived eye size using a psychophysical method. The results showed that low eyebrows (i.e., closer to the eyes) make the eyes appear larger, suggesting that the assimilation of eyes into the eyebrows is stronger when the eye-eyebrow distance is shorter. The results also demonstrated that the application of eye shadow also makes the eyes look larger. Moreover, the effect of eye shadow is more pronounced when viewed from a distance. In order to investigate the mechanism of the eye size illusion demonstrated in Experiment 1, Experiment 2 measured the magnitude of the Delboeuf illusion at a viewing distance of 0.6 m or 5 m, with or without gray gradation simulating the eye shadow that was used in Experiment 1. The experiment demonstrated that the Delboeuf illusion is modulated by viewing distance and gradation in the same way as the eye size illusion. These results suggest that the eye size illusion induced by the eyebrows and the Delboeuf illusion involve the same mechanism, and that eye shadow causes the assimilation of the eyes into itself and enhances assimilation between the eyes and the eyebrows.

We investigated whether the position of the eyebrows influences the perceived shape of the eyes by employing psychophysical measurements. Experiment 1 used arched and straight eyebrows at five different inclinations as stimuli and measured the perceived inclination of the eyes. The results demonstrated that the eyes are perceived to be somewhat inclined in the same direction as the eyebrows. Experiment 2 measured the perceived eye size by manipulating the distance between the eyes and the eyebrows and the curvature of the eyebrows across three levels. The results showed that the lower eyebrows (ie closer to eyes) made the eyes appear larger and the higher eyebrows made the eyes appear smaller, while eyebrow curvature had no effect on perceived eye size. Experiment 3 examined the role of the eye eyebrow distance in the eye inclination illusion shown in experiment 1. The eye inclination illusion was unaffected by the eye eyebrow distance, suggesting that the eye inclination illusion and the eye size illusion may involve different kinds of assimilation. These illusions are discussed in terms of face perception and possible practical applications.

Recognition memory performance for familiar faces is better than that for unfamiliar faces. However, it is unclear whether this familiarity effect also occurs for unfamiliar faces which resemble familiar faces. In Experiment1, we tested recognition memory for unfamiliar faces, and showed that unfamiliar faces that resemble familiar faces are recognized more accurately than are unfamiliar faces that do not. In Experiment2, we attempted to measure how accurately the degree of resemblance is remembered. We had participants remember unfamiliar faces that resembled either familiar faces or unfamiliar faces. Then the participants were asked to choose the face that they thought they had seen from an array of faces whose degree of resemblance was systematically varied. The results demonstrated that resemblance to familiar faces enhances encoding of facial information, and that the degree of resemblance to familiar faces is exaggerated in memory. Experiment3 indicated that people perceive mild anti-caricatures to be most like the real faces that are familiar to them. This finding suggests that exaggerated resemblance in memory is not due to exaggerated representations of familiar faces.

We examined the perception of depth and stability when viewing a video movie made with a camera that moved laterally back and forth 65mm. The two viewing conditions were: (a) head movement synchronized to the stimulus movement and (b) head stationary. In Experiment 1 (N=16), both conditions showed approximately the same magnitude of apparent depth. We argue that (a) in the head movement condition, observers used the cue produced by observer-produced motion parallactic depth, whereas (b) in the no head movement condition, they used the kinetic depth cue or cue(s) from "structure from motion". In Experiment 2 (N=15), the head movement condition showed a greater stability (less perceived motion) compared to the head stationary condition. The results indicate that simulating observer-produced motion parallax (head movement condition) on a video movie of an actual object has no advantages in terms of depth perception. The advantage lies in producing greater stability.

In this article, we provided a mathematical model for analyzing the distribution of reaction time and estimated which types of visual search processes would be observed, such as memory-driven or memory-free types mentioned in Horowitz and Wolfe (2003). Our model was a convolution of the Weibull and Gaussian distributions (Weibull-Gaussian model). We conducted visual search experiments and model fittings for the obtained data. The model comparison revealed that the Weibull-Gaussian model was more appropriate than the ex-Gaussian model. Applying the model to the data revealed that the parameter indicating the type of process changed within a session. These results indicated that the visual search processes were not fixed in one type.