The Act of Answering Questions Elicited Differentiated Responses in a Concealed Information Test.

The concealed information test (CIT), a psychophysiological detection of deception test, compares physiological responses between crime-related and crime-unrelated items. In previous studies, whether the act of answering questions affected physiological responses was unclear. This study examined effects of both question-related and answer-related processes on physiological responses. Twenty participants received a modified CIT, in which the interval between presentation of questions and answering them was 27 s. Differentiated respiratory movements and cardiovascular responses between items were observed for both questions (items) and answers, while differentiated skin conductance response was observed only for questions. These results suggest that physiological responses to questions reflected orientation to a crime-related item, while physiological responses during answering reflected inhibition of psychological arousal caused by orienting. Regarding the CIT's accuracy, participants' perception of the questions themselves more strongly influenced physiological responses than answering them.

Entire Sound Representations Are Time-Compressed in Sensory Memory: Evidence from MMN.

In order to examine the encoding of partial silence included in a sound stimulus in neural representation, time flow of the sound representations was investigated using mismatch negativity (MMN), an ERP component that reflects neural representation in auditory sensory memory. Previous work suggested that time flow of auditory stimuli is compressed in neural representations. The stimuli used were a full-stimulus of 170 ms duration, an early-gap stimulus with silence for a 20-50 ms segment (i.e., an omitted segment), and a late-gap stimulus with an omitted segment of 110-140 ms. Peak MMNm latencies from oddball sequences of these stimuli, with a 500 ms SOA, did not reflect time point of the physical gap, suggesting that temporal information can be compressed in sensory memory. However, it was not clear whether the whole stimulus duration or only the omitted segment duration is compressed. Thus, stimuli were used in which the gap was replaced by a tone segment with a 1/4 sound pressure level (filled), as well as the gap stimuli. Combinations of full-stimuli and one of four gapped or filled stimuli (i.e., early gap, late gap, early filled, and late filled) were presented in an oddball sequence (85 vs. 15%). If compression occurs only for the gap duration, MMN latency for filled stimuli should show a different pattern from those for gap stimuli. MMN latencies for the filled conditions showed the same pattern as those for the gap conditions, indicating that the whole stimulus duration rather than only gap duration is compressed in sensory memory neural representation. These results suggest that temporal aspects of silence are encoded in the same manner as physical sound.

A temporal window for estimating surface brightness in the Craik-O'Brien-Cornsweet effect.

The central edge of an opposing pair of luminance gradients (COC edge) makes adjoining regions with identical luminance appear to be different. This brightness illusion, called the Craik-O'Brien-Cornsweet effect (COCe), can be explained by low-level spatial filtering mechanisms (Dakin and Bex, 2003). Also, the COCe is greatly reduced when the stimulus lacks a frame element surrounding the COC edge (Purves et al., 1999). This indicates that the COCe can be modulated by extra contextual cues that are related to ideas about lighting priors. In this study, we examined whether processing for contextual modulation could be independent of the main COCe processing mediated by the filtering mechanism. We displayed the COC edge and frame element at physically different times. Then, while varying the onset asynchrony between them and changing the luminance contrast of the frame element, we measured the size of the COCe. We found that the COCe was observed in the temporal range of around 600-800 ms centered at the 0 ms (from around -400 to 400 ms in stimulus onset asynchrony), which was much larger than the range of typical visual persistency. More importantly, this temporal range did not change significantly regardless of differences in the luminance contrast of the frame element (5-100%), in the durations of COC edge and/or the frame element (50 or 200 ms), in the display condition (interocular or binocular), and in the type of lines constituting the frame element (solid or illusory lines). Results suggest that the visual system can bind the COC edge and frame element with a temporal window of ~1 s to estimate surface brightness. Information from the basic filtering mechanism and information of contextual cue are separately processed and are linked afterwards.

The relationships among trait anxiety, state anxiety and the goal performance of penalty shoot-out by university soccer players.

The present study examined how the level of trait anxiety, which is a personality characteristic, influences state anxiety and penalty shoot-out performance under pressure by instruction. The high and low trait anxiety groups were selected by using Spielberger's Trait Anxiety Scale, with trait anxiety scores, and control and pressure conditions manipulated by instructions. The participants were two groups of eight university male soccer players. They individually performed 20 shots from the penalty shoot-out point, aiming at the top right and top left corner areas in the soccer goal. Each condition had 10 trials in a within-subject design. The dependent measures comprised the number of successful goals and the state anxiety scores under each instructional condition. The result showed a significant main effect of instruction. State anxiety scores increased more and the number of successful goals decreased more in high trait anxiety groups than in low trait anxiety groups under pressure instructional condition. These findings suggest that players with higher trait anxiety scores tend to experience increased state anxiety under a pressure-laden condition, and higher state anxiety interferes with goal performance.

Awareness of Central Luminance Edge is Crucial for the Craik-O'Brien-Cornsweet Effect.

The Craik-O'Brien-Cornsweet (COC) effect demonstrates that perceived lightness depends not only on the retinal input at corresponding visual areas but also on distal retinal inputs. In the COC effect, the central edge of an opposing pair of luminance gradients (COC edge) makes adjoining regions with identical luminance appear to be different. To investigate the underlying mechanisms of the effect, we examined whether the subjective awareness of the COC edge is necessary for the generation of the effect. We manipulated the visibility of the COC edge using visual backward masking and continuous flash suppression while monitoring subjective reports regarding online percepts and aftereffects of adaptation. Psychophysical results showed that the online percept of the COC effect nearly vanishes in conditions where the COC edge is rendered invisible. On the other hand, the results of adaptation experiments showed that the COC edge is still processed at the early stage even under the perceptual suppression. These results suggest that processing of the COC edge at the early stage is not sufficient for generating the COC effect, and that subjective awareness of the COC edge is necessary.

Smooth pursuit eye movements improve temporal resolution for color perception.

Human observers see a single mixed color (yellow) when different colors (red and green) rapidly alternate. Accumulating evidence suggests that the critical temporal frequency beyond which chromatic fusion occurs does not simply reflect the temporal limit of peripheral encoding. However, it remains poorly understood how the central processing controls the fusion frequency. Here we show that the fusion frequency can be elevated by extra-retinal signals during smooth pursuit. This eye movement can keep the image of a moving target in the fovea, but it also introduces a backward retinal sweep of the stationary background pattern. We found that the fusion frequency was higher when retinal color changes were generated by pursuit-induced background motions than when the same retinal color changes were generated by object motions during eye fixation. This temporal improvement cannot be ascribed to a general increase in contrast gain of specific neural mechanisms during pursuit, since the improvement was not observed with a pattern flickering without changing position on the retina or with a pattern moving in the direction opposite to the background motion during pursuit. Our findings indicate that chromatic fusion is controlled by a cortical mechanism that suppresses motion blur. A plausible mechanism is that eye-movement signals change spatiotemporal trajectories along which color signals are integrated so as to reduce chromatic integration at the same locations (i.e., along stationary trajectories) on the retina that normally causes retinal blur during fixation.

Saccadic compression of rectangle and Kanizsa figures: now you see it, now you don't.

BACKGROUND: Observers misperceive the location of points within a scene as compressed towards the goal of a saccade. However, recent studies suggest that saccadic compression does not occur for discrete elements such as dots when they are perceived as unified objects like a rectangle. METHODOLOGY/PRINCIPAL FINDINGS: We investigated the magnitude of horizontal vs. vertical compression for Kanizsa figure (a collection of discrete elements unified into single perceptual objects by illusory contours) and control rectangle figures. Participants were presented with Kanizsa and control figures and had to decide whether the horizontal or vertical length of stimulus was longer using the two-alternative force choice method. Our findings show that large but not small Kanizsa figures are perceived as compressed, that such compression is large in the horizontal dimension and small or nil in the vertical dimension. In contrast to recent findings, we found no saccadic compression for control rectangles. CONCLUSIONS: Our data suggest that compression of Kanizsa figure has been overestimated in previous research due to methodological artifacts, and highlight the importance of studying perceptual phenomena by multiple methods.

The effect of lutein supplementation on visual fatigue: a psychophysiological analysis.

We used psychophysiological technology to examine the effect of an oral supplement, a combination of lutein, zeaxanthin and blackcurrant extract (LUT), on visual fatigue, within the context of a randomized, double-blind, placebo-controlled cross-over trial. The LUT supplement and placebo samples were randomly assigned to thirteen participants, who took the samples for two LUT (and vice versa) for another 2 week. Each participant completed visual proof reading tasks for 2h during each of four testing sessions. Saccade tests were administered before and after the proof reading task, during which the participants moved their eyes back and forth between two targets positioned in the center of two checkerboards. We recorded EEG, EOG, heart rate, and facial muscle potential/performance during the saccade tests. Blood pressure was measured and subjective fatigue and stress scores were collected before and after the proof reading task. We averaged EEG starting at saccade offset in order to analyze eye fixation related potentials (EFRP). Our results suggested that the proof reading task induced visual fatigue. An analysis of EFRP and other psychophysiological data revealed significant differences between the LUT and placebo conditions. These results suggest that supplementation with LUT could help to reduce symptoms of visual fatigue.

Strength and variability of the backscroll illusion.

When a walking person is presented in a movie, the background image appears to move in a direction opposite to that of the person's locomotion. This study aimed to quantify the strength of this backscroll illusion and to examine interobserver and intraobserver variability. Stimuli were movie clips that presented a walking person in profile against a background of dynamic grating composed of two vertical sinusoidal gratings moving in opposite directions. Employing a motion-nulling method, we controlled the ratio of luminance contrasts of the component gratings to determine points that canceled the percept of unidirectional motion in the grating background. Results across 50 observers showed that the backscroll illusion disappeared when a luminance contrast of moving grating components consistent with a walker's direction was about twice as high as that for the opposite motion direction. Intraobserver variability was relatively small. However, nulling points for individual observers were more variable under conditions with dynamically moving walkers than conditions presenting only a static picture of a walker. We speculated on the underlying mechanisms of the backscroll illusion in relation to similar phenomena.

Effects of communication skills on stress responses while speaking Japanese and English.

The present study was conducted to examine the effects of communication skills on stress responses, such as physiological (blink and heart rate), emotional (state of anxiety and mood), and behavioral responses (smiling and expressing an opinion) in stressful communication situations, specifically answering questions and giving a speech in Japanese and English. Participants were 32 students (16 men and 16 women; Mage = 19.5 yr., SD = 1.3) attending a Japanese university. A high communication skills group was selected from the upper tertile scores of the Social Skills Inventory, and a low communication skills group was selected from the lower tertile scores. Analysis indicated that individuals who had high communication skills performed without heart-rate increase and with more positive attitude during stressful communication tasks. Individuals who had low communication skills displayed higher anxiety prior to the experiment than those who had high communication skills.

Infants' sensitivity to shading and line junctions.

We examined the sensitivity to shading and line junction cues in human infants aged 5-8 months using computer-generated displays containing a rectangular-wave grating and a serrated aperture. In Experiment 1, infants were presented with a pair of displays: a two-dimensional to three-dimensional (2D-3D) display, alternating between 2D and 3D images, and a 2D-2D display, alternating between two 2D images. The 3D image consisted of black-and-white borders aligned with the peaks of a serrated aperture, creating the appearance of a 3D folded surface. The 2D image consisted of the black-and-white borders misaligned with the peaks of a serrated aperture, which does not create a 3D impression for adults. Seven- and 8-month-old infants looked longer at the 2D-3D display than the 2D-2D display. In contrast, 5- and 6-month-old infants did not exhibit a looking preference. In Experiment 2, we used images with double-cycle rectangular-wave gratings to impair shading information. These images consisted of black-and-white borders aligned with half of the peaks and misaligned with latter half of the peaks of a serrated aperture, giving the appearance of surface markings. Seven- and 8-month-old infants did not exhibit a significant difference in preference between the two test displays. These results could not be explained by the young infant's failure of discrimination due to the experimental procedure (Experiment 3). These results showed that the sensitivity to shading and line junctions change between 5-6 and 7-8 months of age.

Reduction of stimulus visibility compresses apparent time intervals.

The neural mechanisms underlying visual estimation of subsecond durations remain unknown, but perisaccadic underestimation of interflash intervals may provide a clue as to the nature of these mechanisms. Here we found that simply reducing the flash visibility, particularly the visibility of transient signals, induced similar time underestimation by human observers. Our results suggest that weak transient responses fail to trigger the proper detection of temporal asynchrony, leading to increased perception of simultaneity and apparent time compression.

Biological motion alters coherent motion perception.

When a movie presents a person walking, the background appears to move in the direction opposite to the person's gait. This study verified this backscroll illusion by presenting a point-light walker against a background of a random-dot cinematogram (RDC). The RDC consisted of some signal dots moving coherently either leftward or rightward among other noise dots moving randomly. The method of constant stimuli was used to vary the RDC in motion coherence from trial to trial by manipulating the direction and percentage of the signal dots. Six observers judged the perceived direction of coherent motion in a two-alternative forced-choice procedure. Response rates for coherent motion perception in the direction opposite to walking were evaluated as a function of motion coherence. The results showed that the psychometric function shifted toward the direction determined by a bias in the opposite direction to the walker. The mean threshold was about half as high as that in a control condition in which the positions of the point-lights were scrambled to impair the recognition of the walker. The results demonstrate that biological motion noticeably affects the appearance of motion coherence in the background.

Asymmetry in the perception of motion in depth induced by moving cast shadows.

An expanding object, which may represent an approaching motion, is easier to detect than a contracting one, which may represent a receding object. To confirm the generality of asymmetry in the detection of approaching and receding motions, we focused on the perception of apparent motion in depth created by moving cast shadows. The visual search for an approaching target among receding distractors was more efficient than for the opposite condition (Experiment 1). However, this asymmetry disappeared when a light shadow was added (Experiments 2 and 3). This suggests that the visual system is specialized to detect approaching motion defined by cast shadows, as well as other three-dimensional cues such as expanding motion and shading.

The effects of linear perspective on relative size discrimination in chimpanzees (Pan troglodytes) and humans (Homo sapiens).

In this study, we tested the corridor illusion in three chimpanzees and five humans, applying a relative size discrimination task to assess pictorial depth perception using linear perspective. The subjects were required to choose the physically larger cylinder of two on a background containing drawn linear perspective cues. We manipulated both background and cylinder size in each trial. Our findings suggest that chimpanzees, like humans, exhibit the corridor illusion.

Backscroll illusion in far peripheral vision.

The backscroll illusion refers to the apparent motion perceived in the background of a movie image that presents a locomotive object such as a person, an animal, or a vehicle. Here, we report that the backscroll illusion can occur in far peripheral visual fields at retinal eccentricity of more than 30 degrees. In psychological experiments, we presented a walking person in profile against an ambiguously moving background of vertical counterphase grating. This stimulus, which subtended 30 degrees of visual angle in width and height, was projected onto a hemispheric screen and positioned at horizontal eccentricity between 0 degrees and 50 degrees at intervals of 10 degrees. The eccentricity was changed randomly trial by trial, and stimulus duration was as short as 350 ms so that observers could not effectively move their eyes to the stimulus. Six observers viewed the stimulus either monocularly or binocularly and reported their perceptual impression for the grating in a three-alternative forced-choice procedure: drifting left, drifting right, or flickering. Results showed that the grating appeared to move in the opposite direction of walking at high probabilities even in the far periphery. Additional experiments confirmed that walking action could be recognized from the far peripheral stimulation. Our findings suggest that the visual system uses high-level object-centered motion signals to disambiguate retinal motion signals in the whole visual field.

Perception of motion trajectory of object from the moving cast shadow in infants.

A moving cast shadow of the object affects the perception of the object's trajectory in adults [Kersten, D., Mamassian, P., & Knill, D. C. (1997). Moving cast shadow induce apparent motion in depth. Perception, 26, 171-192]. In the present study, we investigated by using a habituation-dishabituation procedure whether infants at 4- to 7-months old discriminate the motion trajectory of a ball from the moving shadow it casts. In Experiment 1, 4- to 5-month-old and 6- to 7-month-old were tested for ability to discriminate between a "depth" display containing a ball and a cast shadow with a diagonal trajectory and an "up" display containing a ball with a diagonal trajectory and a cast shadow with a horizontal trajectory. Six- and 7-month-old, but not 4- and 5-month-old, infants looked significantly longer at the "up" display than at the "depth" display. In Experiment 2, we tested whether 4- to 5-month-old and 6- to 7-month-old infants would perceive "up" motion as categorically different from "depth" depending on the object's 3-D trajectory. We used displays containing a ball and a cast shadow with the same trajectories as those in Experiment 1 except that the cast shadows appeared above the ball. These displays did not produce 3-D impressions in adults. Neither age group of infants exhibited significant differences between "up" and "depth" displays. When the results from the two experiments are considered, 6- and 7-month-old infants discriminated the motion trajectory of the ball from the moving cast shadows. This developmental emergence of depth perception from a moving cast shadow at 6 months of age is consistent with that of other pictorial depth cues.

A continuously lit stimulus is perceived to be shorter than a flickering stimulus during a saccade.

When subjects made a saccade across a single-flashed dot, a flickering dot or a continuous dot, they perceived a dot, an array (phantom array), or a line (phantom line), respectively. We asked subjects to localize both endpoints of the phantom array or line and calculated the perceived lengths. Based on the findings of Matsumiya and Uchikawa (2001), we predicted that the apparent length of the phantom line would be larger than that of the phantom array. In Experiment 1 of the current study, contrary to the prediction, the phantom line was found to be shorter than the phantom array. In Experiment 2, we investigated whether the function underlying the filled-unfilled space illusion (Lewis, 1912) instead of the function underlying the saccadic compression could explain the results. Subjects were asked to localize both endpoints of a line or an array while keeping their eyes fixated. Although the results of Experiment 2 showed that the perceived length of a line was shorter than that of an array, the function underlying the filled-unfilled illusion could not fully account for the results of Experiment 1. To explain the present results, we proposed a model for the localization process and discussed its validity.

Comparison of blinking behavior during listening to and speaking in Japanese and English.

Blinking behavior during conversation may be different between conditions in listening and responding to questions because sifting attention from external to internal is possibly associated. The purpose of this study was to compare blinking behavior, duration, heart rates, and mental states during the tasks of listening to and responding to questions in Japanese and English. Participants were 67 (35 men and 32 women) undergraduate students. Blink rate while responding to questions in English did not differ from that while responding to questions in Japanese, but blink rate while listening to questions in English was significantly reduced compared to that while listening to Japanese. While anxiety and uneasiness were increased by the English conversation, blink rate and heart rate were decreased. Blinking behavior may be related to thinking and attention.

Comparison between the lambda response of eye-fixation-related potentials and the P100 component of pattern-reversal visual evoked potentials.

The purpose of this study was to compare the lambda response of eye-fixation-related potentials (EFRPs) with the P100 component of pattern-reversal visual-evoked potentials. EFRPs were obtained by averaging EEGs time-locked to the offset of the saccade. The dipole of the lambda response and that of the P100 component were estimated by the dipole-tracing method (Musha & Homma, 1990). The locations of their dipoles at the occipital sites were very close to each other when the difference waveform, which was calculated by subtracting the EFRP to the patternless stimulus from the EFRP to the patterned stimulus, was used for the lambda response. This finding implies that the lambda response and P100 have a common neural generator in the visual cortex. However, the peak latency of the lambda response was shorter than that of P100. The saccades in the EFRP trial were considered to be the cause of the difference.