Though recent studies have shown that rodents express emotions with their face, whether emotional expression in rodents has a communicative function between conspecifics is still unclear. Here, we demonstrate the ability of visual recognition of emotional expressions in laboratory rats. We found that Long-Evans rats avoid images of pain expressions of conspecifics but not those of neutral expressions. The results indicate that rats use visual emotional signals from conspecifics to adjust their behaviour in an environment to avoid a potentially dangerous place. Therefore, emotional expression in rodents, rather than just a mere ‘expression’ of emotional states, might have a communicative function.

The 20-item prosopagnosia index (PI20) was developed for assessing congenital prosopagnosia, which is characterized by severe facial recognition deficits in the absence of any obvious neurological deficit. We aimed to develop a Japanese version of the PI20 (PI20-J) scale and evaluate its validity and reliability. In study 1, we confirmed the internal consistency, test-retest reliability, and concurrent validity of the scale. In study 2, we examined the relationships between PI20-J score and facial recognition performance and found a moderate correlation between them. In study 3, we examined whether the PI20-J score is related specifically with facial recognition performance, or with general object recognition performance. We found that participants with a high PI20-J score showed weaker facial recognition performance than those with a low PI20-J score. In contrast, the object recognition performance did not depend on the score. Our results suggest that the PI20-J score is related specifically with facial recognition performance. We conclude that PI20-J is highly reliable and valid as a selfreported measure for congenital prosopagnosic traits.

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Preference formation, which is fundamental to personality and daily behavior, is affected by eye movements (i.e. attention). In the last two decades, much research has examined the relationship between decision-making, such as preference formation, and attention (e.g. Smith & Krajbich, 2018). For example, Krajbich and his colleagues showed that gaze toward an option can be considered to be a facilitator of the option's value and that the value of the option can be modeled computationally by using a measure of gazing time toward the option (Krajbich, Armel, & Rangel, 2010; Krajbich & Rangel, 2011). Moreover, manipulating gazing patterns toward each option unconsciously affects a choice (Pärnamets et al., 2015; Shimojo, Simion, Shimojo, & Scheier, 2003). Thus, it is apparent that attention has a crucial role in decision-making. The gaze bias effect is one of the well-known phenomena demonstrating the role of attention on decision-making. When people are faced with a decision, their gaze tends to be biased toward the option they finally choose. This phenomenon is known as the gaze bias effect and has received attention from many scholars

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