Eye tracking research technologies are often used to study how individuals attend visually to different types of AAC displays (e.g. visual scene displays, grid displays). The assumption is that efficiency of visual search may relate to efficiency of motor selection necessary for communication via aided AAC; however, this assumption has not received direct empirical study. We examined the relation between speed of visual search and speed of motor selection of symbols. Ten individuals on the autism spectrum (AS; Study 1) and nine with Down syndrome (DS; Study 2) participated in a search task using simulated AAC displays with a main visual scene display (VSD) and a navigation bar of thumbnail VSDs. Participants were given an auditory prompt to find one of four thumbnail VSDs in the navigation bar. Eye tracking technologies measured how long it took participants to fixate visually on the thumbnail VSD, and recorded how long it took participants to select the thumbnail VSD with a finger. A statistically significant relationship emerged between visual fixation and selection latencies, confirming the positive relationship between visual processing and motor selection for both groups of participants. Eye tracking data may serve as a useful proxy measure for evaluating how display design influences selection of AAC symbols, especially when individuals are unwilling or unable to comply with traditional behaviorally-based assessment tasks.