Effects of information conflict and complexity in visual figures on voluntary visual exploration, using structural information theory

This study was designed to examine the effects of information conflict and complexity on voluntary visual exploration quantitatively. 31 adults viewed each of 16 slides of geometrical figures and places for as long as they wished. The stimuli had two values of information conflict and complexity which had been calculated by means of structural information theory. Free looking times indicated that only when information conflict was low, voluntary visual exploration was positively correlated with complexity. Furthermore, voluntary visual exploration correlated positively with information conflict when complexity was low.     

Emotions Evoked by Viewing Pictures may Affect Temporal Aspects of Visual Processing

We examined how impression (such as safety, pleasantness, and impact), as well as emotional arousal and valence, evoked by viewing a picture affects temporal resolution of visual processing and perceived picture duration. In the first experiment as an index of temporal resolution of visual processing, we measured the noticeable duration of a monochrome picture after presenting a color picture. In the second experiment, we measured the duration of the picture presentation, which was equivalent to the duration of the presentation of a gray rectangle that should not evoke specifically safe or pleasant impressions. We found that the minimum duration in which an observer could notice a monochrome image in viewing a dangerous picture was shorter than that in viewing safe pictures. We also found that observers overestimated the duration of the picture presentation in viewing dangerous pictures. However, there was no significant correlation between the results of the two experiments. These results suggest that the basis for improvement of the temporal resolution in visual processing differs from that for the elongation of the perceived duration.     

A way to install conditioned modulation in the Rescorla-Wagner Axiom: The amplifier model of Pavlovian conditioning (AMP)

Although the Rescorla-Wagner axiom has been successful in explaining and predicting many phenomena in Pavlovian conditioning, it offers no explanation for the ability of stimuli to modulate conditioned responding to other stimuli (i.e., the occasion-setting effect). This article provides a mathematical model for Pavlovian conditioned modulation by adding simple rules to the Rescorla-Wagner axiom. In spite of its rudimentary stage, the proposed model can explain many of the basic findings of modulatory learning and suggests some new areas of research.     

Time-shrinking: a discontinuity in the perception of auditory temporal patterns.

Recent research at our laboratories in the field of human auditory time perception revealed that the duration of short empty time intervals (less than approximately 200 msec) is considerably underestimated if they are immediately preceded by shorter time intervals. Within a certain range, the amount of subjective time shrinking is a monotonous function of the preceding time interval; the shorter it is, the more it shrinks its successor. In the present study, the preceding interval was kept constant at 50 msec, and the following interval, for which the duration had to be judged, varied from 40 to 280 msec. The results showed that at up to 100 msec, the perceived duration increased to a much lesser extent than did the objective duration. Beyond 120 msec, the perceived duration quickly increased and reached a veridical value at 160 msec. Such a sudden change of perceived duration in a temporal pattern in which the objective duration varies gradually indicates a typical example of categorical perception. We suggest that such a categorization of the time dimension might be a clue for processes of speech and music perception.     

On the perception of two successive sound bursts

Summary This paper is concerned with both time perception and the methodology of perceptual psychology. The perception of the pattern of two successive sound bursts was studied by two different methods, i.e., magnitude estimation and phenomenal report. The temporal interval between the bursts was varied from 38 ms to 3394 ms. First, the observer estimated the duration or speed of each pair by a number without modulus. The estimations could not be fitted by a single power function across the entire range of intervals. That is, the exponent changed discontinuously. Next, the observer categorized freely the impressions of all the pairs. The quality of the phenomenon changed at the point where the exponent changed. All the observers arrived at the same three categories expressing the phenomena of the pairs. The boundaries between them corresponded approximately to the intervals of 150 ms and 2000 ms. The pairs in the middle category were often associated with body movements. The other categories also are of a unique nature. Finally, the possibility and the usefulness of employing psychophysical methods and phenomenological methods together is discussed.We are grateful to Professor Y. Umeoka, University of Tokyo, for his constant advice     

Failure of hierarchical conditional rule learning in the pigeon (Columba livia)

Pigeons were trained with a conditional discrimination task in three-key operant chambers. Choosing either the left or right key was followed by food according to combinations of three preceding events: (a) a houselight illumination condition (dark or light), (b) presence or absence of green flashes on the three keys, (c) a color (amber or blue) of the center sample key. With these 2×2×2 event combinations, eight types of correct trials were prepared: (1) dark→no flash→amber→LEFT, (2) dark→no flash→blue→RIGHT, (3) dark→flash→amber→RIGHT, (4) dark→flash→blue→LEFT, (5) light→no flash→amber→RIGHT, (6) light→no flash→blue→LEFT, (7) light→flash→amber→LEFT, and (8) light→flash→blue→RIGHT. Seven of these eight types were used for training of a given bird, and then the remaining trial type was presented as the test. If the birds had learned the conditional structure of the events (the hierarchical switching rule), they would have responded correctly to the test type. However, they chose the opposite side key, suggesting that they had learned cue configuration or multiple rules to solve the task. Accepted after revision: 13 January 2001 Electronic Publication     

Neuromagnetic signals associated with reading a kanji character formed by combining two kanji radicals

To find out which brain regions are responsible for the mental construction and recognition of a kanji character initiated by visually presented kanji radicals, rather than by information retained in the memory, a left hen radical and the corresponding right tsukuri radical were simultaneously presented randomly to either the left or right visual field of seven subjects. Thirty left hen radicals and the corresponding right tsukuri radicals were prepared as stimuli; this combination formed over 500 real or pseudo kanji characters. Instead of their usual left and right positions, the left hen radical was always presented above the right tsukuri radical. As quickly and correctly as possible, the subjects released a key when two kanji radicals constituted a single real kanji character and released another key otherwise. We recorded neuromagnetic responses as well as accuracy and reaction time. Left visual field superiority was observed as regards accuracy. This is in good agreement with previous neuropsychological results. Equivalent current dipoles were localized mainly in the left and/or right occipitotemporal regions (ventral visual pathways), the bilateral occipitoparietal regions (dorsal visual pathways) including the supramarginal region, and the areas surrounding the left superior temporal cortex. We suggest that these regions are related to reading and the mental construction of a kanji character from its radicals.     

Illusory temporal order for stimuli at different depth positions

We used four experiments to examine how the perceived temporal order of two visual stimuli depends on the depth position of the stimuli specified by a 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 distant stimulus before the nearer stimulus (Experiments 1 and 2). This illusory temporal order was found only for sudden stimulus presentation (Experiment 3). These results suggest that a common processing, which is triggered by sudden luminance change, underlies this illusion. The strength of the illusion increased with the disparity gradient and the disparity size (Experiment 4). We propose that this illusion has a basis in the processing of motion in depth, which would alert the observer to a potential collision with an object that suddenly emerges in front of the observer.     

A link between stress and depression: shifts in the balance between the kynurenine and serotonin pathways of tryptophan metabolism and the etiology and pathophysiology of depression

Alteration of tryptophan (TRP) metabolism elicited by proinflammatory cytokines has gained attention as a new concept to explain the etiological and pathophysiological mechanisms of major depression. The kynurenine (KYN) pathway, which is initiated by indoleamine 2,3-dioxygenase (IDO), is the main TRP metabolic pathway. It shares TRP with the serotonin (5-HT) pathway. Proinflammatory cytokines induce IDO under stress, promote the KYN pathway, deprive the 5-HT pathway of TRP, and reduce 5-HT synthesis. The resultant decrease in 5-HT production may relate to the monoamine hypothesis of major depression. Furthermore, metabolites of the KYN pathway have neurotoxic/neuroprotective activities; 3-hydroxykynurenine and quinolinic acid are neurotoxic, whereas kynurenic acid is neuroprotective. The hippocampal atrophy that appears in chronic depression may be associated with imbalances in neurotoxic/neuroprotective activities. Because proinflammatory cytokines also activate the hypothalamo-pituitary-adrenal (HPA) axis, these imbalances may inhibit the hippocampal negative feedback system. Thus, changes in the TRP metabolism may also relate to the HPA axis-hyperactivity hypothesis of major depression. In this article, we review the changes in TRP metabolism by proinflammatory cytokines under stress, which is assumed to be a risk factor for major depression, and the relationship between physiological risk factors for major depression and proinflammatory cytokines.     

The category of 1:1 ratio caused by assimilation of two neighboring empty time intervals

We investigated the perception of temporal patterns of two neighboring empty time intervals, t1 and t2, in this order. In a previous study, we reported that bilateral assimilation took place during t1 and t2, as well as unilateral assimilation. [Miyauchi, R. & Nakajima, Y. (2005). Bilateral assimilation of two neighboring empty time intervals. Music Perception, 22, 411-424]. The points of subjective equality (PSEs) of t1 and t2 approached each other. We speculated that these temporal patterns would yield nearly 1:1 ratios perceptually despite the change in the physical temporal ratio between t1 and t2. However, we were uncertain whether these temporal patterns were really perceived as having 1:1 ratios. In the present study, we conducted three experiments. In Experiment 1, we measured subjective similarities of two temporal patterns and analyzed the results by hierarchical cluster analysis and multidimensional scaling. The temporal patterns, where the physical ratio between t1 and t2 was varied systematically, were divided into three clusters, and one cluster consisted of the temporal patterns within a range of -80 ms 相似文献