Abstract
We have revealed a “gaze cascade effect” (Shimojo, Simion et. al, 2003) as an illustration of the mechanism of preference decision making. It refers to a tendency of gaze being gradually biased towards choice, interpreted as indicating a contribution of the orienting behavior to preference decisions. The present study tests the robustness and generality of the effect and interpretation in two particular conditions. First, observers were shown the same face pairs twice, with an inter-session delay of 1 day and had to decide which face was more attractive. Approximately 80% of all the decisions were identical from one session to the next. We show a gaze cascade effect in both sessions and in the reversed decision trials when analyzed separately. We confirm thus that the gaze cascade accompanies the decision process even when implicit or explicit memory of a past decision exists, suggesting that preference formation, not memory consolidation, needs the assist of gaze for functioning. Second, we evaluate the contribution of the orienting behavior to preference decisions by minimizing the cognitive input. Observers chose the more attractive face in a pair while only being able to see through a small gaze-contingent window, thus visualizing at most one facial feature at a time, with no configural information. If the cascade effect was the result of an early attractiveness bias in the face pairs, this task should not show it at all. Instead, we found a cascade effect of similar size, but 4 times longer (earlier onset) then when observers could see the whole face. This confirms that the smaller the cognitive input in a preference decision, the larger the assist of the orienting behavior in making a choice. Altogether, the results are consistent with our model, in which cognitive and orienting inputs feed into a decision module and are integrated over time until the signal passes a “consciousness threshold” for the decision to be made.