Abstract
Imagine that you are in front of a vending machine with a few seconds available to purchase a food item. The available items vary both in subjective value - how much you like each - and in their visual attractiveness or saliency. What is the nature of the interaction between value and saliency? In our recent eye-tracking study, subjects made a choice between two food items with different subjective values, as indicated by a priori subject's liking ratings for each item (Milosavljevic, et al. 2008). The results from 7 subjects indicate that simple value-based choices can be made accurately (85.7%), with a mean reaction time of 582ms. To study the extent to which these choices are influenced by their value versus their saliency, we followed the same procedure (Milosavljevic, et al. 2008) while manipulating the saliency of the food items. We did so by embedding the items in a background with 1/f2 noise in spatial frequency — meant to simulate naturalistic backgrounds with clutter — while matching the background color to the mean color of one of the two food items presented. To further decrease the saliency of the item, we also decreased its contrast. Preliminary results show that when one item has much higher value than the other, choices are driven by the value and are independent of saliency. In particular, on trials where one item has the highest subjective value but the other item is very salient, the conflict is resolved in favor of the high-value option. However, saliency plays a strong role in the choices when the two food items have similar values — the more salient item is chosen faster and more often than the less-salient item.