Effects of mild psychological stress on facial impressions.

Introduction: Appearance plays an important role in maintaining a positive impression in social interactions. Psychological stress is known to have an adverse effect on facial skin, as indicated in previous studies. However, no study has investigated the negative effect of stress on facial impressions. Therefore, we aimed to investigate changes in impressions from facial images before and after mental stress tasks using an online survey. Method: Thirteen Japanese men were recruited to have their facial photographs taken before and after undergoing a psychological stress task. We observed the physiological effects of an increased heart rate and decreased blood flow on the cheek skin. Four average facial images were created for each time point (control: "baseline;" stress: "0H," "1H," and "3H") from their facial photographs. An online survey was conducted with 700 Japanese participants, who compared the "baseline" to other images and selected one of two options in each of the six questionnaire items of impressions. Results: The results showed that the rate of participants who chose "baseline" was significantly lower in the items "looks tired," "looks old," and "looks irritated" and higher in "looks clean-cut" and "looks healthy" compared to other images created from photographs after the stress task ("0H," "1H," and "3H"). Conclusion: These results suggest that psychological stress loading not only causes physiological changes in autonomic nervous activity and skin blood flow but also negatively impacts facial impressions for a few hours following a mild stress load.

Neural correlates of product attachment to cosmetics.

The neurobiological basis of brand and product attachment has received much attention in consumer neuroscience research, although it remains unclear. In this study, we conducted functional MRI experiments involving female users of famous luxury brand cosmetics as participants, based on the regions of interest involved in human attachment and object attachment. The results showed that the left ventral pallidum (VP), which is involved in positive reward, and the right posterior cingulate cortex (PCC), which is involved in self-concept, a key concept in object attachment, are the core regions in cosmetic attachment. Moreover, the performed psychophysiological interaction analyses showed that VP-temporoparietal junction connectivity positively correlated with activity in the dorsal raphe nucleus, and PCC-anterior hippocampus (aHC) connectivity positively correlated with subjective evaluation of attachment. The former suggests that object attachment is a human-like attachment and a stronger tendency of anthropomorphism is associated with stronger feelings of security. The latter suggests that the individual's concept of attachment as well as the relationships with the attached cosmetics are represented in the aHC, and the PCC-aHC associations produce subjective awareness of the attachment relationships. These associations between memory and reward systems have been shown to play critical roles in cosmetic attachment.

Reliability of Online Surveys in Investigating Perceptions and Impressions of Faces.

Online experimental methods are used in psychological studies investigating the perceptions and impressions of facial photographs, even without substantial evidence supporting their reliability and validity. Although, the quality of visual stimuli is more difficult to control remotely, the methods might allow us to obtain a large amount of data. Then the statistical analysis of a larger volume of data may reduce errors and suggest significant difference in the stimuli. Therefore, we analyzed the reliability and validity of online surveys in investigating the perceptions (shine, red, and dark) and impressions (attractiveness, trustworthy, and so on) of facial photographs created from averaged faces with skin tones modified using computer graphics (CG). In this study, we conducted online (Online1) and laboratory experiments with well-controlled conditions (Control). For each experiment, 50 participants (men and women in Japan, age: 20-59years) completed the same questionnaire regarding their impressions of the same 28 CG facial photographs. The results showed significant correlations between the two experiments for all 19 items in the questionnaire. SD in the Online1 compared to the Control from the stimuli and individual differences were 56-84 and 88-104% in each questionnaire items, respectively. Moreover, the rates of mismatching perceptual evaluations to the corresponding physical features demonstrated in the photographs were 4.9-9.7% on average in an additional online survey of another 2,000 participants (Online2). These results suggest that online surveys can be applied to experiments to investigate impressions from CG facial photographs instead of general laboratory experiment by obtaining an appropriate number of participants to offset larger statistical errors that may result from the increased noise in the data from conducting the experiment online.

Luxury Cues of Cream Heighten the Reward Value of Its Tactile Experience.

In our previous study, the brain activity of areas related to social dominance [dorsomedial prefrontal cortex (DMPFC)] and reward [ventral striatum (VS)] was compared before and after providing information (cue) indicating that an applied cream was luxury. Both the DMPFC and VS showed significantly higher activation after this cue, and the cue also facilitated the connection between the DMPFC and VS via the dorsolateral prefrontal cortex (DLPFC). Therefore, it may likewise have an effect on primary (SI) and secondary (SII) somatosensory areas. In the current study, we explored this hypothesis by performing correlation analyses of the same data and found a significant positive correlation between the VS and the right SII during the application of the cream even before the cue, and significant correlations between the VS and the right SI, SII, and DLPFC after. These results suggest that the emotional value based on texture is mainly processed through the connection between the SII and VS, and luxury cues further facilitate the connection between the VS and the SI, which plays a role in discriminating the physical aspects of creams. Therefore, we provide neuroscientific evidence of the synergistic effect of luxury cues on pleasant tactile and social dominance feelings.

Luxury Cues Facilitate the Connection Between Social Dominance and Reward Mediated by the Lateral Prefrontal Cortex.

Luxury skin care products have emotional value because of their texture and accompanying product information. The influence of these factors appears to be linked. Here, we investigated the influence of information on brain activity during hand massages with skin care creams in healthy female volunteers. In the first session, participants received hand massages using two skin care creams (luxury and basic). In the second session, participants were shown information which indicated whether each cream was a luxury or basic product during the massage. In the third session, they received a hand massage as per the first session. Functional magnetic resonance imaging data were recorded during massages. Differential activity in the ventral striatum (VS), the caudate nucleus, and the dorsomedial prefrontal cortex (DMPFC) was significantly higher in the third session than in the first session. Moreover, differential activity in the right dorsolateral prefrontal cortex (DLPFC) was positively correlated with differential activity in both the VS and the DMPFC in the third session. These results suggest that the neural substrate of the effects is based on both the dopamine reward system and the self-other distinction system involved in social dominance and that the right DLPFC plays a critical role in the association between these systems.

Analysis of skin conductance response during evaluation of preferences for cosmetic products.

We analyzed skin conductance response (SCR) as a psychophysiological index to evaluate affective aspects of consumer preferences for cosmetic products. To examine the test-retest reliability of association between preferences and SCR, we asked 33 female volunteers to complete two experimental sessions approximately 1 year apart. The participants indicated their preferences in a typical paired comparison task by choosing the better option from a combination of two products among four products. We measured anticipatory SCR prior to expressions of the preferences. We found that the mean amplitude of the SCR elicited by the preferred products was significantly larger than that elicited by the non-preferred products. The participants' preferences and corresponding SCR patterns were well preserved at the second session 1 year later. Our results supported cumulating findings that SCR is a useful index of consumer preferences that has future potential, both in laboratory and marketing settings.

Ginkobiloba extract improves working memory performance in middle-aged women: role of asymmetry of prefrontal cortex activity during a working memory task.

In order to clarify the mechanism through which extract of Ginkgo biloba leaves (EGb) improves cognitive function, we examined the effects of EGb on cerebral blood oxygenation in the prefrontal cortex (PFC) and on performance during a working memory task, using near-infrared spectrometry (NIRS). First, we evaluated differences in behavioral performance of the Sternberg working memory test (ST) and in the activation pattern of the PFC during ST between 15 young and 19 middle-aged healthy women. Then, we examined the effect of EGb (120 mg/day for 6 weeks) on ST performance and PFC activation pattern in the middle-aged group. The middle-aged group exhibited a longer reaction time (RT) in ST than the young group and showed a different PFC activation pattern during ST, i.e., the middle-aged group showed bilateral activation while the young group showed right-dominant activation. In the middle-aged group, administration of EGb for 6 weeks shortened the RT of ST and changed the PFC activation pattern to right-dominant, like that in the young group. The results indicate the PFC plays a role in the physiological cognitive function-enhancing effect of EGb. EGb might improve working memory function in middle-aged individuals by counteracting the occurrence of aging-related hemispheric asymmetry reduction.