What Are the Chances? fMRI Correlates of Observing High and Low-Probability Actions

Abstract

Cognitive scientists often use probabilistic equations to model human behavior in ambiguous situations. How, where, and even if such probabilities are represented in the human brain remains largely unknown. Here, we manipulated the probability of simple bottle-pouring action based on two considerations, the relative fullness of two glasses and the relative distance between the two glasses and the bottle. Whole brain functional magnetic resonance imaging was used to measure brain activity while participants viewed probable and improbable pouring actions. Improbable actions elicited increased activity in the theory of mind (ToM) network, commonly found active when trying to grasp the intentions of others, whereas probable actions elicited increased activity in the human mirror neuron system (hMNS) and areas associated with mental imagery and memory. These data provide novel insight into the brain mechanisms humans use to distinguish between high and low-probability actions.

The left inferior parietal lobe represents stored hand-postures for object use and action prediction

“…The overlap in activation in the left IPL and the left PMC for the independent effects of target objects and action cue, may indicate that upcoming actions are predicted, either through a process of motor imagery (when no action cue is presented) or by matching the observed action to stored hand postures for object use (when an action cue is presented). The finding that the activation of the AON is modulated not only as a function of the low-level kinematic features of the observed action, but also by the involvement of semantics for action is in line with the view that the AON represents higher-level aspects of observed actions as well, such as the correctness or meaningfulness of an action (Koelewijn et al, 2008; Newman-Norlund et al, 2010, 2013; Stapel et al, 2010). The present study extends these findings, by indicating a stronger involvement of the AON for unpredictable actions that require the use of action semantics.…”

“…For instance, observing someone grasping a full bottle of wine is more predictable in a context in which both glasses are empty, but less predictable in a context where both glasses are full (cf. Newman-Norlund et al, 2013). Accordingly, the aim of the present fMRI study was to investigate how activation in the AON is modulated as a function of the predictability of an action involving multiple objects that require the use of action semantics.…”