"Never tell me the odds" do people emphasize value or probability when choosing between alternatives?


When people have to select and then aim to one of two target-penalty prospects that have equal maximum expected gain (MEG), they tend to select prospects with a higher probability of target hits than prospects with lower penalty values (Neyedli & Welsh, 2015). The present study explored whether participants held this tendency when selecting the prospect via a key-press (i.e., a non-motor task) without prior aiming experience thus having little feedback on the outcome of their decision. Participants chose between prospects via left/right key-presses that 1) had different MEG, with either only the values (Penalty condition) or probabilities (Distance condition) differing between prospects; and 2) had similar MEG (Similar condition), with one prospect having a higher probability of hitting the target but a higher penalty value and the other having a lower probability of hitting the target but a lower penalty value. In the Penalty and Distance conditions, participants chose the prospect with the larger MEG. In the Similar MEG condition participants, on a group level, chose the prospects with higher probability and with lower value equally. However, a participant-by-participant analysis revealed 3 subgroups: those with value preferences, probability preferences, or no preference. Interestingly, performance metrics during a motor task (i.e., variable and constant error) and small variations in MEG difference between prospects in the Similar condition did not predict choice behaviour. Thus, probability preference is not consistent across individuals when interaction with target-penalty prospects and prior motor experience is not given.

Acknowledgments: Dr. Tim Welsh, Dr. Heather Neyedli, and Joseph Manzone (PhD Candidate)