Surprising adaptivity to set size changes in multi-attribute repeated choice tasks

It is well-established that decision makers react to changes in choice set size by adapting their information search processes, but there is less consensus about how quickly they do so. Recent findings characterize decision-makers as ‘sticky adapters’ who continue to use information search processes that they used in previous decision situations. This paper assesses the adaptivity of these processes to changes in set size, i.e. in the number of alternatives in a choice task. We track decision-makers’ eye movements across eight multi-attribute choice tasks of increasing, decreasing or constant size and determine decision makers’ amount of information search, filtration, search pattern, and directional processing. Overall, we find fast and nearly complete adaptation to changes in set size. The only exception is a persistence of attribute-wise processing as set size increases.