We reviewed the properties of mental imagery in aphantasia—a condition whereby individuals have difficulty in forming mental imagery, although their visual perception is intact. Individuals with aphantasia have demonstrated lower priming effects regarding visual imagery in the binocular rivalry paradigm. However, these individuals can complete visual short-term memory tasks normally via the use of verbal strategies (i.e., nonvisual strategies). Few studies have provided clear evidence regarding its neurological basis. Thus, future research is necessary to obtain evidence thereof. For object and spatial imagery, nearly no differences existed in spatial imagery between individuals with and without aphantasia with regard to the rating scores of imagery questionnaires, although individuals with aphantasia had a dysfunction in object imagery. We review the imagery model and the debate regarding aphantasia for which findings from studies on aphantasia may provide important suggestions for perceptual and imagery studies. We expect a better understanding of aphantasia will be promoted in society by developing studies that apply various approaches—including case studies, psychological tests, brain science, and educational support—following the present review article.

Flickering patterns can be uncomfortable for normal observers and may even produce epileptic seizures in photosensitive observers. These adverse effects are aspects of “visual discomfort.” To avoid inducing visual discomfort, exploring the underlying mechanisms contributing to discomfort from a source of flicker is important from a scientific perspective and an applied perspective. In this review, the recent literature examining the effects of amplitude and phase spectrum, adaptation, and ambient light level on discomfort from flicker is summarized. The involvement of low-level and higher-level visual processing in visual discomfort in the temporal domain is discussed. Several unsolved problems are also outlined for future studies.

Respiratory phases are associated with the performance on various cognitive tasks. This paper reviews behavioral and psychophysiological studies that compared the effects of inhalation and exhalation phases on perception and cognition. First, previous findings are summarized, based on psychological functions such as simple motor reaction, attention, and memory. Second, four methodical difficulties inherent in conducting such studies are discussed: choice of respiratory route (i.e., nasal vs. oral), manner of breathing (i.e., spontaneous vs. controlled), instruction on how to breathe, and manipulation of the timing of stimulus presentation. Finally, several research questions are raised to understand the relationship between respiratory phases and psychological functions.

The psychological network approach introduced by Kashihara (2019) had the potential to promote tailored therapies for mental disorders, and a cutting-edge commentary by Matsumoto (2020) provided suggestions for future research to integrate cognitive experimental data into psychological network analyses. In response to Matsumoto (2020), this paper reveals that researchers using psychological network approaches should consider the processes of theory construction, including feedback loops between theories, phenomena, and data. First, this paper introduces the status of theory crisis in current psychological science. Second, it discusses that the psychological network approach has been developed to overcome the limitations of latent variable approaches of psychopathology and that it sequentially updates the understanding of psychopathologies by examining the correspondence between network theories, phenomena of mental disorders, and empirical symptom data. Third, this paper responds to the main suggestions provided by Matsumoto (2020) to enhance the sound development of the psychological network approach in the field of psychopathology. Every response emphasizes that psychological network analyses should be used according to theories and phenomena.