Our previous study has demonstrated that in the cardinal orientation, offset detection depends on the relative position of the vernier bars, i.e., how the left and right or upper and lower vernier bars are displaced from each other in space (Karim & Kojima, 2008, 2010). The present study examined whether the fact can be generalized to the oblique orientation. Experiment 1 demonstrated that for a pair of vernier bars, one displaced from the other and arranged side-by-side with a large gap between them at +45° orientation observers were, on average, somewhat better at discriminating an offset if the relative position of the lower right-hand bar was to the right of the upper left-hand bar than vice versa. A similar asymmetry was evident in Experiment 2, where observers judged vernier offset for a pair of bars at -45° orientation. In that case, average acuity was significantly better when the relative position of the upper right-hand bar was to the right of the lower left-hand bar than the opposite. The asymmetries in performance were consistent across the two orientations and did not diminish with learning, thus indicating configuration-specific processing of the vernier stimuli.
Autism is a disorder of neural development characterized by impairments in social cognition and communications. By applying multidimensional scaling to the analysis of temporo-spatial gaze behaviors, we quantitatively demonstrated that normal control participants shared highly stereotypical gaze patterns while viewing socially relevant video stimuli, whereas children and adults with autism spectrum disorders (ASD) were variable in their gaze patterns. Many distant cortical areas has been implicated for such deficits of social ability. From these observations, we hypothesized that ASD derives from anomalous neural connections in their brain with long-range underconnectivity. In support of the hypothesis, we found a weakness of individuals with ASD in naming familiar objects moved behind a narrow slit, which was worsened by the absence of local salient features. Temporal integration of successive visual information during slit viewing involves a distributed cortical network, including higher visual areas and parietal association areas. Thus, the long-range underconnectivity implicated in the autistic brain may result in a deficit in visual temporal integration across these areas.
Various aspects of visual information are analyzed by parallel circuits in the retina. The outputs are sent through optic fibres, which consist mostly of the axons of retinal ganglion cells, to multiple visual centres in the brain. At present we do not know how visual information is coded by spike trains in retinal ganglion cells. It has been reported that oscillatory synchronized activities are generated among visual neurons in a manner which depends on certain key features of light stimulation. Although these activities are assumed to play an important role in perceptual integration, their functional significance has yet to be elucidated. Using frogs we performed multi-electrode recordings from isolated retinas and behavioral tests. An expanding dark spot evoked oscillatory synchronized activities among dimming detectors (OFF-sustained ganglion cells), and elicited escape behavior. Intraocular injection of GABA_A and GABA_C receptor antagonists suppressed and enhanced escape behavior, respectively. The behavioral modification correlated only with the change in oscillatory synchronized activities among dimming detectors. These activities are likely to encode escape-related information in frogs.
The artificial vision makes the machine substitute a part of the visual system, and enables to see again. In Japan, about 188,000 blind people exist. The main four causative diseases are diabetic retinopathy, glaucoma, age-related macular degeneration, and inherited retinal dystrophy. Because age-related macular degeneration and inherited retinal dystrophy damage the photoreceptor cell and the retinal pigment epithelium chiefly, if we can offer some information to the retinal ganglion cell, it will be able to bring the input as somewhat sight to the brain. On the other hand, diabetic retinopathy and glaucoma cause the degeneration of the retinal ganglion cell. Therefore, rebuilding the vision of diabetic retinopathy and glaucoma is impossible with electrical retinal stimulation. We guess that the ideal artificial vision system is a type which gets the image by the intraoccular camera and which stimulates occipital lobe by light. It will have high resolution and will be able to be applied to most diseases in the near future.
With the development of Cognitive Behavioral Therapies and Evidence-Based Practice, the American Psychological Association and the British Psychological Society are large umbrella organization under which clinical psychologists cooperated with the researchers of psychonomic science. The benefits of cooperation between clinical psychology and psychonomic science in Japan are discussed, taking an example of the study of schizotypal personality traits (schizotypy). A perspective that situates schizophrenia on a continuum implies that a cognitive psychological approach to the schizotypal personality in the general population could be useful to understand schizophrenia. The establishment of abnormal psychology in Japan is proposed, which will interface clinical psychology practice with academic psychology.
Perceptual and cognitive mechanisms play crucial roles in developmental disorders, such as developmental dyslexia, and autism. With regard to developmental dyslexia, various hypotheses such as disorders in phonological processing, the magnocellular system, and cerebrum-cerebellum circuits have been discussed. Perceptual stability may be an important factor in the problems with reading in developmental dyslexia. The human brain may not have evolved sufficiently to automatically process "letter" as with "face". This could explain why it is difficult to transform and integrate information related to sounds and letters/words in developmental dyslexia. Studies in cognitive neurosciences should contribute to determining the cause of developmental dyslexia and other disorders.
An historical outline of schizophrenia research is described with the close relationship between psychiatry and psychology. Especially, we focused and discussed on the theory of information processing deficits in schizophrenia generated by Broadbent's information processing model (filter theory of attention). In order to show effective methods to elucidate dynamic and active aspects of schizophrenic pathology, we introduced our psychophysiological researches on smooth pursuit eye movements, saccades and prepulse inhibition using the paradigm of self-stimulation. Finally, we suggest that it is necessary to have collaboration between psychiatrists and psychologists for further fruitful research.
To examine whether individuals with ADHD show a deficit in interference control, Stroop/reverse-Stroop interference and the processing of global and local information were compared between a group with predominantly inattentive type ADHD and a non-ADHD group. Participants with ADHD showed a control deficit in reverse-Stroop interference and in local-to-global interference. Results indicate that reverse-Stroop and Navon tasks are promising diagnostic tools in the assessment of ADHD.
To investigate how quickly we can perceive being watched by other people, we evaluated the effect of duration on the quantitative judgment of gaze direction and the perception of "being looked at". The stimuli were models of heads generated by a computer, and the rotation angle and gaze direction of each head was varied independently. The participants were asked to judge whether the stimulus was looking at them (being-looked-at judgment), and to judge where the stimulus was looking (quantitative gaze direction judgment). The results revealed that neither the direction that gives the best perception of being-looked-at, nor the perceptually straight direction of the participants were affected by the duration (100ms, 1000ms, or an unlimited duration). These results indicate that the judgment of whether or not a looker's gaze is directed towards one completes at an early level in the gaze perception process and within 100ms.
We examined whether amblyopic suppression involves luminance-based information. The stimuli consisted of four square patches presented dichtopically so that one eye viewed the top-left and bottom-right patches, while the other eye viewed the top-right and bottom-left patches. The observers adjusted the luminance of a stimulus in order to match the perceived luminance between the two eyes. Amblyopes decreased the luminance of the patches presented to the fellow fixing eye while they increased luminance for the amblyopic eye. Similar results were obtained when only the mean luminance was adjustable and the luminance contrast remaining fixed. These results suggest that the world appears darker when viewed through an amblyopic eye.
By adding small patches of different luminances to a uniform field surrounding a target, the effect of the surrounding luminance on target brightness can be enhanced (articulation effect). The present study investigated whether the articulation effect is governed only by retinal proximity or also affected by spatial organization by common-fate motion. The target in the present study was a moving patch located at the center of an articulated surround. It was moved with small patches and/or the uniform background within the surround with the same speed, direction, and timing. The target was easily grouped with the patches and/or the background depending upon what simultaneously moved, although retinal proximity was kept almost constant. The results indicated clear influences of spatial organization as well as retinal proximity on the articulation effect. These findings suggest that the brightness computation on the articulated field could depend upon both the spatial luminance distribution in the retinal image, and spatial structure where retinal elements were spatially organized by common-fate motion.
Since human hands frequently interact with external objects, it is important to detect events that will occur near the hands as fast as possible. Previous studies have suggested that the visual detection of a target near a hand is facilitated relative to detection distant from the hand (Reed et al., 2006). However, their investigations have focused on the palm, because it is normally the contact surface of the hand. Our study investigated whether a facilitated detection would occur with the back of the hand, that has little interaction with objects, when it was facing towards targets. The results showed a different pattern between the palm of the hand and the back. In addition, this pattern appears to be related to the function of the back of the hand. These results have suggested that the functional characteristics of the surfaces of the hand affect detection of targets near the hand differently.
We investigated the influence of pre-penetration and penetration velocity changes (deceleration/constant velocity/acceleration) on visual hardness judgments. Participants were asked to judge, using an analog scale, the relative hardness of the penetrated objects compared to a standard pattern with no changes in acceleration. The results show that perceptual hardness was higher when the penetrating object decelerated during pre-penetration, or accelerated during penetration, but was lower when the velocity changed from acceleration to deceleration. Our findings reveal that the visual perception of hardness is influenced by velocity changes of the penetrating object during penetration. In addition, the current results imply that velocity change during pre-penetration, which is not directly related to actual penetration in a natural environment, is one factor determining the visual perception of texture.
The radial optic flow sensitivity during locomotion was tested in 4 experiments. The results of the experiments indicated that the optic flow sensitivity was significantly lower in the condition where the visual and vestibular sensory inputs were congruent for the ego-motion direction rather than in the condition where the visuo-vestibular inputs were incongruent. These results suggest that the optic flow sensitivity is suppressed during locomotion when the relationship of the visual and vestibular sensory inputs is in a normal state.
Letter discrimination is impaired when the letter is presented within an apparent motion (AM) trajectory of a spot. This finding suggests that the internal representation of AM stimuli can interfere with perception at a relatively high processing level. Here, we investigated whether AM interference also occurs at an earlier processing level. We found that the detection threshold of patterns defined by a luminance dimension was impaired in an AM trajectory. Further, this suppressive effect of AM became weaker when the contrast polarity, orientation, or shape of the inducers of the AM and the target was inconsistent. These findings suggest that AM stimuli and their internal representation affect early visual processes involved in detecting a pattern and that the internal representation of an AM stimulus reflects the stimulus's attribute.
Accumulated evidence has shown that the perception of a visual object is altered by an auditory stimulus. This study investigated how the "offset" timing of an auditory stimulus would influence the perceived position of a moving visual object. A visual target moved smoothly in a horizontal direction and disappeared at an unpredictable position. Concurrently with the visual target, a pure-tone sound was continuously presented. The onset of the sound was temporally aligned with that of the visual target but the offset timing varied. The results showed that the perceived final position changed systematically with the temporal gap between the visual and sound offsets. This finding suggests that an offset of an auditory signal may signal changes of a visual object.
In motion-induced blindness (MIB), a visual target is frequently perceived to disappear on moving random dots (Bonneh, Cooperman, & Sagi, 2001). In this study, we reported a new crossmodal effect: that a short noise burst releases MIB. In Experiment 1, we showed that the target which disappeared in MIB reappeared soon after the presentation of the burst at the same position as the target. In Experiment 2, we elucidated that the reappearance of the target started approximately 400ms after the burst presentation. In Experiment 3, the bursts were randomly presented for the 30-second stimulus period. The results showed that the disappearance duration of the target was shorter in the burst condition than that in the no-burst condition. These results clearly indicate that abrupt auditory stimuli shorten the duration of reactivating a visual target when the audio-visual stimulation spatially corresponds.
Finger pointing is used to cue an interesting object or position. In this study, we evaluated the area size designated by finger pointing using a visual search task. In general, a target is detected faster when it was cued by any method, including finger pointing. Experiment 1 revealed that observers conduct a visual search faster when the target position is specified by pointing, than in a no-cue condition. The improvement using pointing was comparable to that by conventional cueing with a line segment. In Experiment 2 the stimulus display was physically delimited by line frames to reduce the number of stimulus items to undergo a visual search. The data were compared to those from Experiment 1 to obtain the actual limitation realized by pointing. This analysis suggested that the observers' attention was limited to within 10 to 15 degrees radius by the effect of pointing..
Identification of a visual target is impaired by a salient distractor which is presented simultaneously or previously (attentional capture). It has also been reported that there is interference with identification of a target when it is followed by another target within 500ms (attentional blink). Although it has been assumed that these performance subtracters share a common underlying mechanism, there is no direct evidence supporting this view. We examined the intra-individual correlations of these performance subtracters observed in two attentional capture tasks (a spatial attentional capture task and a spatio-temporal attentional capture task) and an attentional blink task. The results from 135 participants showed no significant correlations among the deficits in these three tasks, suggesting that the underlying mechanisms of these deficits were independent.
We investigated one of the basic properties of selective memory accuracy of a brief visual event scene in a short-range of temporal sequence. In the present study, we used a slow appearance frequency of a serial visual presentation of letters for already segmented scenes of a time sequence. A brief visual change simultaneously appeared with one of a letter scene as a salient event. In four experiments, we examined the temporal and spatial effect of this peculiar visual event on the memery of the letters, which appeared independently. The results of the present study presumably indicate that if a salient visual change occurs with a close temporal proximity to a sequence of brief scenes, then our memory system assigns a high priority to the scene of the peculiar event as a snapshot. In addition, the memory of the scene details are preserved only for the information registered as belonging to the same object.