Individual differences in perceptual and cognitive decision-making in response to near identical options

Abstract

Every day people deal with the “exploration/exploitation dilemma”: Deciding when to stay with the current option or move to a new one. Most research in the literature focuses on the influence that external variables exert on people’s decisions (e.g., punishments/rewards). However, little is known about how people deal with identical or nearly identical options in the absence of external bias. The general assumption present in both human and animal models is that, in the absence of obvious cost, individuals would naturally explore. This thesis directly tests this assumption in six experimental studies by examining people’s behaviour when facing identical or nearly identical options, both in perceptual and behavioural tasks. Despite the obvious differences existing between behavioural and perceptual tasks, people are essentially making similar decisions (to explore a different option; or to exploit the current option). Hence, the broad hypothesis under investigation is that similar tendencies should be found within the same person, across domains. Furthermore, because the impact of external bias was minimal in the tasks used, any differences in people’s explorative tendencies should be attributed to stable factors, such as personality traits. To this end, we individuated two broad personality frameworks (the Big Five Model and the Schizotypy construct). In Study 1-4 we examined how people deal with the trade-off between exploration and exploitation from a perceptual perspective, by using binocular rivalry (where an observer is faced with identical, and equally valid, perceptual solutions). In Study 1 we demonstrated that people high in the Openness to Experience trait significantly differed from other people in the way they flexibly explored and combined basic visual stimuli. In Study 2 we looked at whether differences existed in people’s tendencies to explore perceptual solutions following changes in transient emotional state (i.e., arousal) and found that general changes in one’s mood, but not specific type of mood, have a significant impact. In Study 3 we examined whether changes in alternations (i.e., fast or slow) between perceptual solutions were associated with stable personality traits and found that slower alternations were associated with Conscientiousness, characterised by self-control and determination. In Study 4 we examined whether abnormalities in the way perceptual stimuli are “flexibly” processed in people with schizophrenia can be similarly found in a non-clinical population. We found that increased schizotypy was associated with an increase of mixed percept during binocular rivalry. Study 5-6 examined how people deal with the trade-off between exploration and exploitation from a behavioural perspective, by using the Virtual Environment task, which was designed and developed specifically for this aim. The Virtual Environment task was inspired by the animal literature (i.e., the optomotor maze; van Swinderen, 2011) where flies need to choose between identical turning points to advance in the maze. Study 5 presents the findings from the six pilot task. Each version was sequentially developed to rule out potential confounding variables, which might have been responsible for the “unusual” stereotypical behaviour that emerged. That is, people displayed exclusively exploitative tendencies, with no exploration. Study 6 presents the findings from the virtual environment task. Here people showed variability in their explorative tendencies, however, against our prediction an increase of exploration was linked to those personality traits capturing self-discipline (Conscientiousness), rather than flexibility and the tendency to engage with possibilities (Openness to Experience). This was the first evidence of important similarities between perception and behaviour in the way people deal with the trade-off between exploration and exploitation. For example, in relation to the number of decisions, or sampling, of the environment. Our findings also highlighted two important issues in the exploration/exploitation literature. First, they cast doubt on the assumption that humans have a “natural drive to explore” in the absence of rewards. As shown in the difficulties to design appropriate stimuli to observe a balance between exploration/ exploitation in the first place. Second, because our findings did not replicate data from the animal literature, they represent a cautionary tale in interpreting findings from the animal model to be considered valid for humans.