Is decision-making influenced by interactions between extended wakefulness and weak emotional stressors? An experimental study.

In this study, we aimed to determine whether 21-hour continuous wakefulness decreases performance in the Iowa Gambling Task and examine the effect of the interaction between a weak emotional stressor and prolonged continuous wakefulness on the decision-making process, as measured by the Iowa Gambling Task. Approximately half of 38 healthy college students were in the sleep deprivation condition (they performed the task at 4:30 a.m.); the remainder were in the daytime condition (they performed the task during the day). The participants in each sleep condition were further divided into non-exposed and exposed to an emotional stressor via a social exclusion procedure before the task, with the Iowa Gambling Task score as the dependent variable. In the sleep deprivation condition, performance in the final block of the task was significantly worse in the group with an emotional stressor than the group without. There was no main effect of sleep conditions or emotional stressors on the task performance in either block. The results of this study suggest that even 21 hours of continuous wakefulness, which can occur in daily work life, may prevent appropriate learning in people exposed to an emotional stressor, even if the stress caused due to it is low.

Shadows alter facial expressions of Noh masks.

BACKGROUND: A Noh mask, worn by expert actors during performance on the Japanese traditional Noh drama, conveys various emotional expressions despite its fixed physical properties. How does the mask change its expressions? Shadows change subtly during the actual Noh drama, which plays a key role in creating elusive artistic enchantment. We here describe evidence from two experiments regarding how attached shadows of the Noh masks influence the observers' recognition of the emotional expressions. METHODOLOGY/PRINCIPAL FINDINGS: In Experiment 1, neutral-faced Noh masks having the attached shadows of the happy/sad masks were recognized as bearing happy/sad expressions, respectively. This was true for all four types of masks each of which represented a character differing in sex and age, even though the original characteristics of the masks also greatly influenced the evaluation of emotions. Experiment 2 further revealed that frontal Noh mask images having shadows of upward/downward tilted masks were evaluated as sad/happy, respectively. This was consistent with outcomes from preceding studies using actually tilted Noh mask images. CONCLUSIONS/SIGNIFICANCE: Results from the two experiments concur that purely manipulating attached shadows of the different types of Noh masks significantly alters the emotion recognition. These findings go in line with the mysterious facial expressions observed in Western paintings, such as the elusive qualities of Mona Lisa's smile. They also agree with the aesthetic principle of Japanese traditional art "yugen (profound grace and subtlety)", which highly appreciates subtle emotional expressions in the darkness.

The mysterious noh mask: contribution of multiple facial parts to the recognition of emotional expressions.

BACKGROUND: A Noh mask worn by expert actors when performing on a Japanese traditional Noh drama is suggested to convey countless different facial expressions according to different angles of head/body orientation. The present study addressed the question of how different facial parts of a Noh mask, including the eyebrows, the eyes, and the mouth, may contribute to different emotional expressions. Both experimental situations of active creation and passive recognition of emotional facial expressions were introduced. METHODOLOGY/PRINCIPAL FINDINGS: In Experiment 1, participants either created happy or sad facial expressions, or imitated a face that looked up or down, by actively changing each facial part of a Noh mask image presented on a computer screen. For an upward tilted mask, the eyebrows and the mouth shared common features with sad expressions, whereas the eyes with happy expressions. This contingency tended to be reversed for a downward tilted mask. Experiment 2 further examined which facial parts of a Noh mask are crucial in determining emotional expressions. Participants were exposed to the synthesized Noh mask images with different facial parts expressing different emotions. Results clearly revealed that participants primarily used the shape of the mouth in judging emotions. The facial images having the mouth of an upward/downward tilted Noh mask strongly tended to be evaluated as sad/happy, respectively. CONCLUSIONS/SIGNIFICANCE: The results suggest that Noh masks express chimeric emotional patterns, with different facial parts conveying different emotions This appears consistent with the principles of Noh which highly appreciate subtle and composite emotional expressions, as well as with the mysterious facial expressions observed in Western art. It was further demonstrated that the mouth serves as a diagnostic feature in characterizing the emotional expressions. This indicates the superiority of biologically-driven factors over the traditionally formulated performing styles when evaluating the emotions of the Noh masks.

A high-loaded hemisphere successfully ignores distractors.

We used a response competition paradigm to investigate whether a distractor is effectively rejected under conditions where it is projected to a highly-loaded hemisphere. In two experiments we asked right-handed participants to identify a target among five task-relevant letters while they ignored a distractor. We manipulated both the distractor visual-field (low-load/high-load) and the compatibility of the target and the distractor. In the low-loaded visual-field, we presented a distractor with one task-relevant stimulus to one visual-field and the remaining task-relevant stimuli to the opposite visual-field. In the high-loaded visual-field, we presented a distractor and task-relevant stimuli in reverse. In Experiment 1 (left/right), we found a compatibility effect for the low-loaded, but not for the high-loaded visual-field. In Experiment 2, this modulation of the compatibility effect did not appear when the upper/lower visual-field was manipulated. These findings demonstrate that a distractor is successfully ignored when it is presented to a highly-loaded hemisphere.

Hemisphere division and its effect on selective attention: a generality examination of Lavie's load theory.

The present study examined the role of visual presentation mode (unilateral vs. bilateral visual fields) on attentional modulation. We examined whether or not the presentation mode affects the compatibility effect, using a paradigm involving two task-relevant letter arrays. Sixteen participants identified a target letter among task-relevant letters while ignoring either a compatible or incompatible distracter letter that was presented to both hemispheres. Two letters arrays were presented to visual fields, either unilaterally or bilaterally. Results indicated that the compatibility effect was greater in bilateral than in unilateral visual field conditions. Findings support the assumption that the two hemispheres have separate attentional resources.

[Independent resource of each hemisphere modulates selective attention].

Based on the load theory and the assumption that each hemisphere has independent resources, we examined the effects of perceptual load in each hemisphere on the compatibility effect. In Experiments 1, and 2ab, two letter-strings were presented to the left and right visual-fields with a distracter, which was presented on the center of the screen. Two conditions were prepared by pairing a letter-string which contained a target with one which did not. Right-handed participants were asked to identify the target in the letter-strings while ignoring the distracter. The results showed that the compatibility effect was larger when the perceptual load of the letter-string which did not contain a target was low. This suggests that the residual resources of the hemisphere where the target was not projected facilitated the processing of the distracter. In Experiment 3, two letter-strings were presented to both hemispheres. The results showed that the compatibility effect was constant, irrespective of the perceptual load of the letter-string. Our findings suggested that selective attention is modulated by the resources of each hemisphere.

[The effects of global and local processing on intra- and inter-hemispheric interaction].

Our study investigated intra- and inter-hemispheric interference in local and global processing. A pair of single letter and a Navon-type hierarchical pattern was presented to a unilateral (Within-Field) or bilateral visual field (Across-Field), where one letter was the target and a Navon-type hierarchical pattern as a distracter. In Experiment 1, where a small letter was the target, the local interference was larger when the distracter was presented to the left hemisphere (LH) than when it was presented to the right hemisphere (RH), for both presentation modes (Within- and Across Field). The size of the global interference was constant irrespective of the side where the distracter was presented, for both presentation modes. In Experiment 2, which used a large-single letter as a target, only a global interference was found and the size of the effect was larger when the distracter was presented to the RH than the LH in the Within-Field condition. These findings suggested that intra- and inter-hemispheric interactions are modulated by global and local processing.

[The asymmetry of interhemispheric interaction in reverse-stroop task].

The purpose of the present study was to examine the effect of interference on interhemispheric interaction in the reverse-stroop task. In two experiments, color-word in black ink and color-patch in red or blue ink were briefly presented to a bilateral visual-field (BVF). The participants were asked to identify the color word, ignoring the color patch. In Experiment 1, color-words written in kanji character were used as target ([Chinese character: see test] or [Chinese character: see test]). In Experiment 2, color-words written in kana character were used as target ([Chinese characters: see test] or [Chinese characters: see test]). The result in Experiment I showed that the size of the interference effect was invariant irrespective of the visual-field of the target. On the contrary, in Experiment 2, the interference effect was larger in the condition where the kana color-word was presented to left visual-field (LVF) than to right visual-field (RVF). These results suggested that the interference effect would be modulated by the dominant hemisphere for processing the target.