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.

Syntactic and Semantic Processing in Japanese Sentence Reading: A Research Using Functional Near-Infrared Spectroscopy (fNIRS).

In order to examine whether syntactic processing is a necessary prerequisite for semantic integration in Japanese, cortical activation was monitored while participants engaged in silent reading task. Congruous sentences (CON), semantic violation sentences (V-SEM), and syntactic violation sentences (V-SYN) were presented in the experiment. The participants' oxygenated hemoglobin concentration changes during the reading task were measured using functional near-infrared spectroscopy. The results suggest that the CON sentences did not require additional cognitive load on syntactic processing or semantic processing. The V-SEM sentences demanded great cognitive load on semantic processing. Besides, it also elicited great cognitive load on syntactic processing. The V-SYN sentences induced great cognitive load on syntactic processing, but it did not induce additional load on semantic processing. These evidence demonstrates that, in Japanese language processing, the difficultness of semantic processing could influence the difficultness of syntactic processing, while the difficultness of syntactic processing would not influence the difficultness of semantic processing. Our findings are suggestive of the possibility that in Japanese language reading, semantic processing precedes syntactic processing, or semantic processing and syntactic processing are in parallel.

Selective adaptation in sentence comprehension: Evidence from event-related brain potentials.

In this study, two event-related potential experiments were conducted to investigate whether readers adapt their expectations to morphosyntactically (Experiment 1) or semantically (Experiment 2) anomalous sentences when they are repeatedly exposed to them. To address this issue, we experimentally manipulated the probability of occurrence of grammatical sentences and syntactically and semantically anomalous sentences through experiments. For the low probability block, anomalous sentences were presented less frequently than grammatical sentences (with a ratio of 1 to 4), while they were presented as frequently as grammatical sentences in the equal probability block. Experiment 1 revealed a smaller P600 effect for morphosyntactic violations in the equal probability block than in the low probability block. Linear mixed-effects models were used to examine how the size of the P600 effect changed as the experiment went along. The results showed that the smaller P600 effect of the equal probability block resulted from an amplitude's decline in morphosyntactically violated sentences over the course of the experiment, suggesting an adaptation to morphosyntactic violations. In Experiment 2, semantically anomalous sentences elicited a larger N400 effect than their semantically natural counterparts regardless of probability manipulation. Little evidence was found in favour of adaptation to semantic violations in that the processing cost associated with the N400 did not decrease over the course of the experiment. Therefore, a dynamic aspect of language-processing system was demonstrated in this study. We will discuss why the language-processing system shows a selective adaptation to morphosyntactic violations.

Similarities and Differences Between Native and Non-native Speakers' Processing of Formulaic Sequences: A Functional Near-Infrared Spectroscopy (fNIRS) Study.

The present study reported an experiment examining whether both native speakers (NSs) and non-native speakers (NNSs) give formulaic sequences (FSs) priority over novel phrases in processing, as the dual route model has postulated. In this experiment, NSs and NNSs were asked to read Japanese versions of semi-transparent restricted collocations (e.g., kenka-o uru 'pick a fight (acc)'), novel phrases (e.g., tomato-o uru 'sell tomatoes (acc)'), and violated phrases (e.g., kenka-o sagasu 'find out a fight (acc)'); and they judged the naturalness of these sequences. Participants' reaction times were measured, as well as their cortical activation. The results revealed that, for the NSs, collocations required shorter reaction times and elicited less cortical activation than the novel stimuli. For NNSs, collocations similarly required shorter reaction times, but they elicited greater cortical activation than novel phrases. These results support the dual route model, both for NSs and NNSs.

Inter-participant variabilities and sample sizes in P300 and P600.

Reliably and efficiently detecting physiological differences between conditions of interest is of importance in psychophysiology. In particular, when it comes to the observation of relatively small differences, such as a P600 effect, a language-related brain potential elicited by ungrammatical sentences compared to grammatical sentences, inter-participant variability is a critical factor since a larger inter-participant variability decreases statistical significance, and therefore increases the necessary sample size. The present study investigated how stable individual P600s are, at which sample sizes the P600 becomes stable, and how many participants are necessary to observe a P600 effect. P600s were recorded from 48 participants, as well as P300 (P3b) from 40 participants for comparison. Unlike the P3b effect, which had an approximately 10 µV difference between the target and standard stimuli, P600 increased in amplitude by only 1.4-1.7 µV at Pz during the processing of ungrammatical sentences relative to the grammatical counterparts. The sample size analysis suggests that 20 to 30 participants are needed to detect a P600 effect at Pz, and the distribution of variances does not change significantly with a larger sample size.

Differences in the efficiency of pattern encoding in relation to autistic-like traits: an event-related potential study.

We examined the effects of complexity on the efficiency of pattern encoding in the general population differing on autism-spectrum quotient (AQ) scores. We compared brain activity (electroencephalography) during a same-different task for High and Low AQ groups. The task was composed of identical comparison and categorical comparison (CC) conditions that presented simple or complex patterns. In the CC condition, the Low AQ showed large P3b amplitudes with simple patterns than with complex patterns, whereas the High AQ showed the same amplitude levels for these patterns. These indicate that, similar to simple patterns, complex patterns are efficiently encoded in the High AQ. Moreover, the High AQ had no impairment in the global pattern encoding compared with the Low AQ.

Reported visual imagery and apparent motion: an event-related potential study.

A previous behavioral study showed that a group of individuals with high vividness of visual imagery (High group), as determined from the score for the Vividness of Visual Imagery Questionnaire (VVIQ), could perceive the apparent motion path more strongly than a group of individuals with low vividness of visual imagery (Low group). To examine the physiological differences underlying these differences in perception, we compared the brain activity during an apparent motion task for the High and the Low groups using electroencephalography. We initially screened 60 potential participants using the VVIQ. On the basis of their scores, we invited 20 people from the lower and the higher ends of the VVIQ distribution to participate in our event-related potential study. Our results showed that individuals in both the High and the Low groups were sensitive to the apparent motion content of the task. Perception of apparent motion evoked a negative potential starting around 90 ms, followed by a positive potential beginning at 150-170 ms after the second stimulus. The scalp distributions of both negative and positive potentials for the High group were broader than those for the Low group. Moreover, the onset of positivity in the High group (150 ms) was earlier than that in the Low group (170 ms). We believe that these results may be mechanistically associated with the differences in the perception of apparent motion between individuals with high and low vividness of visual imagery.