Astrid Hopfensitz

The Modular Nature of Trustworthiness Detection.

The capacity to trust wisely is a critical facilitator of success and prosperity, and it has been conjectured that people of higher intelligence are better able to detect signs of untrustworthiness from potential partners. In contrast, this article reports five trust game studies suggesting that reading trustworthiness of the faces of strangers is a modular process. Trustworthiness detection from faces is independent of general intelligence (Study 1) and effortless (Study 2). Pictures that include nonfacial features such as hair and clothing impair trustworthiness detection (Study 3) by increasing reliance on conscious judgments (Study 4), but people largely prefer to make decisions from this sort of pictures (Study 5). In sum, trustworthiness detection in an economic interaction is a genuine and effortless ability, possessed in equal amount by people of all cognitive capacities, but whose impenetrability leads to inaccurate conscious judgments and inappropriate informational preferences.

Face-ism and kernels of truth in facial inferences

In a recent article in the Science & Society section of this journal [1], Olivola and colleagues delivered a powerful argument about fighting the phenomenon that they called ‘face-ism’.

Low second-to-fourth digit ratio predicts indiscriminate social suspicion, not improved trustworthiness detection

Testosterone administration appears to make individuals less trusting, and this effect has been interpreted as an adaptive adjustment of social suspicion, that improved the accuracy of trusting decisions. Here, we consider another possibility, namely that testosterone increases the subjective cost of being duped, decreasing the propensity to trust without improving the accuracy of trusting decisions. In line with this hypothesis, we show that second-to-fourth digit ratio (2D : 4D, a proxy for effects of testosterone in the foetus) correlates with the propensity to trust, but not with the accuracy of trusting decisions. Trust game players (n = 144) trusted less when they had lower 2D : 4D (high prenatal testosterone), but their ability to detect the strategy of other players was constant (and better than chance) across all levels of digit ratio. Our results suggest that early prenatal organizing effects of testosterone in the foetus might impair rather than boost economic outcomes, by promoting indiscriminate social suspicion.

Can we detect cooperators by looking at their face

Humans are willing to cooperate with each other for mutual benefit—and to accept the risk of exploitation. To avoid collaborating with the wrong person, people sometimes attempt to detect cooperativeness in others’ body language, facial features, and facial expressions. But how reliable are these impressions? We review the literature on the detection of cooperativeness in economic games, from those with protocols that provide a lot of information about players (e.g., through long personal interactions) to those with protocols that provide minimal information (e.g., through the presentation of passport-like pictures). This literature suggests that people can detect cooperativeness with a small but significant degree of accuracy when they have interacted with or watched video clips of other players, but that they have a harder time extracting information from pictures. The conditions under which people can detect cooperation from pictures with better than chance accuracy suggest that successful cooperation detection is supported by purely intuitive processes.

Honest smiles as a costly signal in social exchange (Commentary).

Smiling can be interpreted as a costly signal of future benefits from cooperation between the individual smiling and the individual to whom the smile is directed. The target article by Niedenthal et al. gives little attention to the possible mechanisms by which smiling may have evolved. In our view, there are strong reasons to think that smiling has the key characteristics of a costly signal.

Split-Second Trustworthiness Detection From Faces in an Economic Game

Economic interactions often imply to gauge the trustworthiness of others. Recent studies showed that when making trust decisions in economic games, people have some accuracy in detecting trustworthiness from the facial features of unknown partners. Here we provide evidence that this face-based trustworthiness detection is a fast and intuitive process by testing its performance at split-second levels of exposure. Participants played a Trust game, in which they made decisions whether to trust another player based on their picture. In two studies, we manipulated the exposure time of the picture. We observed that trustworthiness detection remained better than chance for exposure times as short as 100 ms, although it disappeared with an exposure time of 33 ms. We discuss implications for ongoing debates on the use of facial inferences for social and economic decisions.

Mill ownership and farmer's cooperative behavior: the case of Costa Rica coffee farmers

We analyze how Costa Rican coffee farmers behavior in an experimental public good game depends on the type of mill where the farmers sell their coffee (Cooperative vs. privately owned mills), and on the background of their game partners (partners selling to same type of mill or not). We find that cooperative farmers do not display more public good orientation than private market farmers when playing with partners from the same type of mill. However, while farmers selling to private mills make no difference with respect to the background of partners, farmers selling to cooperatives significantly decrease contributions when paired with non-cooperative members. Finally, we study how self-selection into a mechanism that punishes the lowest contributors affects contributions both inside the group and with partners of the opposite background, and show that this increases contributions in the games played with farmers selling to different mill type.

How to Adapt to Changing Markets: Experience and Personality in a Repeated Investment Game

Investment behavior is traditionally investigated with the assumption that risky investment is on average advantageous. However, this may not always be the case. In this paper, we experimentally studied investment choices made by students and financial professionals under favorable and unfavorable market conditions in a multi-round investment game. In particular, the probability of winning was set so that investment in one condition was advantageous, and in one condition was disadvantageous. To investigate who is more likely to adapt their investment behaviors to the changing market conditions, we also measured personality and self-efficacy. We expected that investment behavior in changing markets could be predicted by a combination of experience (students, professionals), personality (anxiety, optimism, impulsivity, and Openness to Experience), and self-efficacy (belief in one’s ability to make good decisions in an investment task). Results indicate that professionals do not significantly differ from students in their decisions. Personality and self-efficacy both predicted investment behavior. In particular, we found that optimism and anxiety were a liability in unfavorable markets, leading to unreasonable levels of risk. Impulsivity was a liability in both favorable and unfavorable markets, leading to high risk on unfavorable markets, and low risk in favorable markets. Openness to experience was an asset in unfavorable markets, leading to adjusted risk taking. Finally, self-efficacy was generally related to higher levels of risk.