Ulf Toelch

Individual consistency and flexibility in human social information use.

Copying others appears to be a cost-effective way of obtaining adaptive information, particularly when flexibly employed. However, adult humans differ considerably in their propensity to use information from others, even when this ‘social information’ is beneficial, raising the possibility that stable individual differences constrain flexibility in social information use. We used two dissimilar decision-making computer games to investigate whether individuals flexibly adjusted their use of social information to current conditions or whether they valued social information similarly in both games. Participants also completed established personality questionnaires. We found that participants demonstrated considerable flexibility, adjusting social information use to current conditions. In particular, individuals employed a ‘copy-when-uncertain’ social learning strategy, supporting a core, but untested, assumption of influential theoretical models of cultural transmission. Moreover, participants adjusted the amount invested in their decision based on the perceived reliability of personally gathered information combined with the available social information. However, despite this strategic flexibility, participants also exhibited consistent individual differences in their propensities to use and value social information. Moreover, individuals who favoured social information self-reported as more collectivist than others. We discuss the implications of our results for social information use and cultural transmission.

The neural underpinnings of an optimal exploitation of social information under uncertainty.

Social information influences decision-making through an integration of information derived from individual experience with that derived from observing the actions of others. This raises the question as to which extent one should utilize social information. One strategy is to make use of uncertainty estimates, leading to a copy-when-uncertain strategy that weights information from individual and social sources based on their respective reliabilities. Here, we investigate this integration process by extending models of Bayes optimal integration of sensory information to a social decision context. We then use a key parameter of our behavioral model in conjunction with functional magnetic resonance imaging to identify the neural substrate that is specifically linked to the fidelity of this integration process. We show that individuals behave near Bayes optimal when integrating two distinct sources of social information but systematically deviate from Bayes optimal choice when integrating individual with social information. This systematic behavioral deviation from optimality is linked to activity of left inferior frontal gyrus. Thus, an ability to optimally exploit social information depends on processes that overcome an egocentric bias, and this regulatory role involves the left inferior prefrontal cortex. The findings provide a mechanistic explanation for observations wherein individuals neglect the benefits from exploiting social information.

Social performance cues induce behavioral flexibility in humans

Behavioral flexibility allows individuals to react to environmental changes, but changing established behavior carries costs, with unknown benefits. Individuals may thus modify their behavioral flexibility according to the prevailing circumstances. Social information provided by the performance level of others provides one possible cue to assess the potential benefits of changing behavior, since out-performance in similar circumstances indicates that novel behaviors (innovations) are potentially useful. We demonstrate that social performance cues, in the form of previous players’ scores in a problem-solving computer game, influence behavioral flexibility. Participants viewed only performance indicators, not the innovative behavior of others. While performance cues (high, low, or no scores) had little effect on innovation discovery rates, participants that viewed high scores increased their utilization of innovations, allowing them to exploit the virtual environment more effectively than players viewing low or no scores. Perceived conspecific performance can thus shape human decisions to adopt novel traits, even when the traits employed cannot be copied. This simple mechanism, social performance feedback, could be a driver of both the facultative adoption of innovations and cumulative cultural evolution, processes critical to human success.

Informational and Normative Influences in Conformity from a Neurocomputational Perspective

We consider two distinct influences that drive conformity behaviour. Whereas informational influences facilitate adaptive and accurate responses, normative influences bias decisions to enhance social acceptance. We explore these influences from a perspective of perceptual and value-based decision-making models and apply these models to classical works on conformity. We argue that an informational account predicts a surprising tendency to conform. Moreover, we detail how normative influences fit into this framework and interact with social influences. Finally, we explore potential neuronal substrates for informational and normative influences based on a consideration of the neurobiological literature, highlighting conceptual shortcomings particularly with regard to a failure to segregate informational and normative influences.

Cross-modal effects of value on perceptual acuity and stimulus encoding

Significance Reward-predicting signals could be acquired through any of our different sensory modalities, but should be used by other senses to achieve fast and accurate behavior. How reward information is communicated across different sensory modalities is unknown. We demonstrate that sounds associated with high rewards increase the sensitivity of vision, even when sounds and their reward associations are task-irrelevant. Multivariate analysis of the simultaneously acquired functional MRI data revealed that high-reward sounds increased the accuracy of stimulus representation in the visual cortex. Multisensory regions of the temporal cortex were modulated by sound values, and the strength of this modulation was correlated with the change in visual acuity. Our results demonstrate a value-driven cross-modal interaction that affects early stages of sensory processing and involves multisensory areas. Cross-modal interactions are very common in perception. An important feature of many perceptual stimuli is their reward-predicting properties, the utilization of which is essential for adaptive behavior. What is unknown is whether reward associations in one sensory modality influence perception of stimuli in another modality. Here we show that auditory stimuli with high-reward associations increase the sensitivity of visual perception, even when sounds and reward associations are both irrelevant for the visual task. This increased sensitivity correlates with a change in stimulus representation in the visual cortex, indexed by increased multivariate decoding accuracy in simultaneously acquired functional MRI data. Univariate analysis showed that reward associations modulated responses in regions associated with multisensory processing in which the strength of modulation was a better predictor of the magnitude of the behavioral effect than the modulation in classical reward regions. Our findings demonstrate a value-driven cross-modal interaction that affects perception and stimulus encoding, with a resemblance to well-described modulatory effects of attention. We suggest that multisensory processing areas may mediate the transfer of value signals across senses.

Competition strength influences individual preferences in an auction game

Highlights • We conducted a repeated all-pay auction experiment with real items.• Participants exhibited dynamic bidding strategies.• Bidding dynamics clearly affected preferences for auctioned items.• Preference changes depended on the effort exerted when winning.

Neural substrates of norm compliance in perceptual decisions

Societal norms exert a powerful influence on our decisions. Behaviours motivated by norms, however, do not always concur with the responses mandated by decision relevant information potentially generating a conflict. To probe the interplay between normative and informational influences, we examined how prosocial norms impact on perceptual decisions subjects made in the context of a simultaneous presentation of social information. Participants displayed a bias in their perceptual decisions towards that mandated by social information. However, normative prescriptions modulated this bias bi-directionally depending on whether norms mandated a decision in accord or contrary to the contextual social information. At a neural level, the addition of a norms increased activity in prefrontal cortex and modulated functional connectivity between prefrontal and parietal areas. The bi-directional effect of our norms was captured by differential activations when participants decided against the social information. When norms indicated a decision in line with social information, non-compliance modulated lateral prefrontal cortex activity. By contrast, when norms mandated a decision against social information norm compliance increased activity in the anterior cingulate cortex. Hence, social norms changed the balance between a reliance on perceptual and social information by modulating brain activity in regions associated with response inhibition and conflict monitoring.

I judge you by your profit: Judgments of effort exerted by self and others are influenced by task contingent rewards

Effort constitutes a major part of cost-benefit calculations underlying decision making. Therefore, estimating the effort someone has spent on a task is a core dimension for evaluating own and others’ actions. It has been previously shown that self-judgments of effort are influenced by the magnitude of obtained rewards. It is unclear, however, whether the influence of reward on effort estimations is limited to self-judgments or whether reward incorporation represents a general computational principle when judging effort. Here we show that people also integrate reward magnitude when judging the effort exerted by others. Participants (N=48) performed an effortful sensorimotor task interleaved with a partner, while rating either their own or the other person’s effort. After each trial but before the effort rating, both participants were informed about the obtained reward. We found that higher rewards led to higher estimations of exerted effort, in self-as well as other-judgments, and this effect was more pronounced for other-judgments. In both types of judgment, computational modelling revealed that reward information and the perceived level of exertion were combined in a Bayes optimal manner to form effort estimates. Remarkably, the extent to which rewards influenced effort judgments was positively correlated with conservative world-views, indicating that the basic computations underlying this behavioural phenomenon might be related to more general beliefs about the association between effort and reward in the society. The integration of reward information into retrospective effort judgments underscores the convergence of multiple information sources that supports adaptive learning and decision making in social contexts.