What Can 1 Million Trials Tell Us About Visual Search?

TLDR

Visual search experiments involve observers scanning a set of items for a target, with reaction time measured against set size to infer underlying search processes, and typically comprise 5–15 subjects completing only a few hundred trials each. This retrospective study analyzes about 1 million trials from 2,500 experimental sessions, each containing a few hundred trials. The extensive data reveal diverse search tasks and indicate that current theories of visual search must be revised.

Abstract

In a typical visual search experiment, observers look through a set of items for a designated target that may or may not be present. Reaction time (RT) is measured as a function of the number of items in the display (set size), and inferences about the underlying search processes are based on the slopes of the resulting RT x Set Size functions. Most search experiments involve 5 to 15 subjects performing a few hundred trials each. In this retrospective study, I examine results from 2,500 experimental sessions of a few hundred trials each (approximately 1 million total trials). These data represent a wide variety of search tasks. The resulting picture of human search behavior requires changes in our theories of visual search.