Diversity of aphantasia revealed by multiple assessments of visual imagery, multisensory imagery, and cognitive style.

Aphantasia-a condition wherein individuals have a reduced or absent construction of voluntary visual imagery-is diagnosed using either the Vividness of Visual Imagery Questionnaire (VVIQ) or self-identification. However, a significant discrepancy exists between the proportions of aphantasia in the populations assessed using these two criteria. It is unclear why the reported proportions differ excessively and what percentage of people cannot form visual imagery. We investigated the replicability of the proportion of people with aphantasia using both criteria in the same population of participants. Therefore, we explored the potential causes of the discrepancy and characteristics of putative aphantasia in terms of multisensory imagery, cognitive style, and face recognition ability. First, we conducted an online sampling study (Study 1: N = 2,871) using the VVIQ, self-identification of a reduction in visual imagery, Questionnaire upon Mental Imagery (QMI), and Verbalizer-Visualizer Questionnaire (VVQ). We found that 3.7 and 12.1% fulfilled the VVIQ and self-identification criteria, respectively, roughly replicating the proportions reported in previous studies. The self-identification criterion-but not the VVIQ criterion-contains items related to face recognition; hence, we suspected that face recognition ability was factor contributing to this discrepancy and conducted another online sampling study (Study 2: N = 774). We found a significant correlation between VVIQ and face recognition ability in the control group with self-identification, but not in the group defined by low VVIQ (VVIQ ≤32). As the participants in the control group with self-identification tended to exhibit moderately high VVIQ scores but low face recognition ability, we reason that the discrepancy can be partially explained by the contamination of individual differences in face recognition ability. Additional analyses of Study 1 revealed that the aphantasia group included participants who lacked all types of sensory imagery or only visual imagery in multisensory imagery and exhibited a non-specific cognitive style. This study indicates that the VVIQ alone may be insufficient to diagnose individuals who report an inability to form visual imagery. Furthermore, we highlight the importance of multiple assessments-along with the VVIQ-to better understand the diversity of imagery in aphantasia.

Auditory startle reflex inhibited by preceding self-action.

A startle reflex to a startle pulse is inhibited when preceded by a prestimulus. We introduced a key-press action (self-action) or an 85 dB noise burst as a prestimulus, followed by a 115 dB noise burst as a startle pulse. We manipulated temporal offsets between the prestimulus and the startle pulse from 30-1,500 ms to examine whether self-action modulates the startle reflex and the temporal properties of the modulatory effect. We assessed eyeblink reflexes by electromyography. Both prestimuli decreased reflexes compared to pulse-alone trials. Moreover, the temporal windows of inhibition were different between the types of prestimuli. A faster maximal inhibition and narrower temporal window in self-action trials suggest that preceding self-action inhibits the startle reflex and allows prediction of the coming pulse in different ways from auditory prestimuli.

Effect of second language exposure on brain activity for language processing among preschoolers.

We investigated brain activity in 3-5-year-old preschoolers as they listened to connected speech stimuli in Japanese (first language), English (second language), and Chinese (a rarely exposed, foreign language) using near-infrared spectroscopy. Unlike the younger preschoolers who had been exposed to English for almost 1 year, brain activity in the bilateral frontal regions of the older preschoolers who had been exposed to English for almost 2 years was higher for Japanese and English speech stimuli than for Chinese. This tendency seemed to be similar to that observed in adults who had learned English for some years. These results indicate that exposure to a second language affects brain activity to language stimuli among preschoolers.

Effects of non-native language exposure on the semantic processing of native language in preschool children.

We investigated the effects of non-native language (English) exposure on event-related potentials (ERPs) in first- and second-year (four- and five-year-old) preschool Japanese native speakers while they listened to semantically congruent and incongruent Japanese sentences. The children were divided into a non-native language exposed group (exposed group) and a group without such experiences (control group) on the basis of their exposure to non-native language. We compared the ERPs recorded from the two groups in each of the two preschool years. N400 was observed both in the first- and second-year preschoolers. Differences owing to exposure to non-native language appeared in the second-year preschoolers but not in the first-year preschoolers. In the second-year preschoolers, the N400 onset in the exposed group was shorter than that in the control group, but there was no difference in the N400 offset between the exposed and control groups. Furthermore, the scalp distribution of the N400 in the exposed group was broader than that in the control group. These results indicate that the time course and scalp distribution of semantic processing for native language sentences in young children fluctuated depending on exposure to non-native language.

Discrete cortical regions associated with the musical beauty of major and minor chords.

Previous research has demonstrated that the degree of aesthetic pleasure a person experiences correlates with the activation of reward functions in the brain. However, it is unclear whether different affective qualities and the perceptions of beauty that they evoke correspond to specific areas of brain activation. Major and minor musical keys induce two types of affective qualities--bright/happy and dark/sad--that both evoke aesthetic pleasure. In the present study, we used positron emission tomography to demonstrate that the two musical keys (major and minor) activate distinct brain areas. Minor consonant chords perceived as beautiful strongly activated the right striatum, which has been assumed to play an important role in reward and emotion processing, whereas major consonant chords perceived as beautiful induced significant activity in the left middle temporal gyrus, which is believed to be related to coherent and orderly information processing. These results suggest that major and minor keys, both of which are perceived as beautiful, are processed differently in the brain.

Brain activity associated with dual-task management differs depending on the combinations of response modalities.

Several functional imaging studies have demonstrated the importance of fronto-parietal network in dual-task management. However, neural correlates underlying the difference in intensity of dual-task interference between the same and different response modalities remain unknown. Therefore, we investigated the relationship between brain activity associated with dual-task management and the combinations of response modalities. We used the dual-task requiring bilateral finger responses (DT-same condition) and that requiring finger and oral responses (DT-different condition) to visual and auditory stimuli. The right premotor cortex, precuneus and right posterior parietal cortex were significantly activated in the DT-same condition. The neural activities in the right premotor cortex significantly correlated to the delayed responses in the DT-same condition relative to the single-task conditions, indicating that the right premotor cortex is partly associated with dual-task management (i.e., the regulation of information flow). In addition, neural activity in this brain region was significantly higher in the DT-same condition than in the DT-different condition, suggesting that the difference in intensity between the same and different response modalities is partly associated with difference in the load on the premotor cortex between the DT-same and DT-different conditions. The significant activation of the parietal cortex also differed between the DT-same and DT-different conditions. These results demonstrate that brain activity associated with dual-task management differs depending on the combination of response modalities and that such a difference in brain activity, particularly in the right premotor cortex, might be partly associated with the difference in intensity of dual-task interference between the DT-same and DT-different conditions.

Presentation of a visual nearby moving object alters stream/bounce event perception.

Two identical visual objects moving across each other in a two-dimensional display can be perceived as either streaming through or bouncing off each other. The bouncing event percept is promoted by the presentation of a brief sound at the point of coincidence of the two objects. In this study, we examined the effect of the presence of a moving object near the two objects as well as the brief sound on the stream/bounce event perception. When both the nearby moving object and brief sound were presented, a streaming event, not a bouncing event, was robustly perceived (experiment 1). The percentage of the streaming percept was also systematically affected by the proximity of the nearby object (experiment 2). These results suggest that the processing of intramodal grouping between a nearby moving object and either of the two objects in the stream/bounce display interferes with crossmodal (audiovisual) processing. Moreover, we demonstrated that, depending on the trajectory of the nearby moving object, the processing of intramodal grouping can promote the bouncing percept, just as crossmodal processing does (experiment 3).