Lana Milman¹ (), Ian Phillips¹, Chaz Firestone¹; ¹Johns Hopkins University

We can often see how easy a physical action is to execute, such as climbing stairs or grasping an object. Is the same true for mental actions? Can we also see how easy it is to execute a cognitive operation, before actually carrying it out? Whereas the perception of physical affordances has a long history in cognitive science, the hypothesis that we perceive “mental affordances” (McClelland, 2020) has received less empirical attention. Here, four experiments explore this hypothesis for the mental affordance “countability”—how easily an array of objects can be precisely counted. In Experiments 1-2, subjects briefly (500ms or 2500ms) saw two “cookies” (circles) containing a number of “M&Ms” (dots), varying in size (large/small/mixed), color (single/mixed), opacity (full/partial), and grouping (clustered/dispersed). Subjects selected whichever cookie seemed easier to count (causing it to reappear onscreen), and then counted that cookie’s M&Ms. In Experiments 3-4, subjects counted a single cookie’s M&Ms, without indicating preference. Results showed that even a 500ms preview was sufficient to form strong preferences for countability, with subjects preferring fully opaque to partially opaque M&Ms, clustered M&Ms to dispersed M&Ms, and large M&Ms over mixed and small M&Ms. However, these impressions were only partially accurate. Subjects performed better with opaque M&Ms, and large as opposed to mixed and small M&Ms, in line with their preferences. But performance was better for dispersed M&Ms than clustered M&Ms—contrary to their preference. Moreover, despite expressing no preference for single over mixed-color M&Ms, subjects performed better with single colors. These results suggest that naïve observers can rapidly form impressions of a mental affordance and use it to guide behavior—but that, just like with physical affordances, we may be imperfectly calibrated to our actual capabilities.