A note on the equality judgment experiment in Itthipuripat, et al. (2019)

Itthipuripat, Chang, Bong, & Serences (2019) investigated the effects of attention on appearance and decision criteria. Using a series of comparative and equality judgment tasks, they determined that most of the effects of attention could be explained as changes in decision criteria; however, their equality judgment experiment did reveal an effect of attention on appearance at low contrasts. Because their analysis reported Cmax, the contrast at which the equality judgement is maximum, and because Cmax is not independent of potential low-contrast response biases, I decided to reanalyze their equality judgment data. Based on this reanalysis, I was not able to rule out a potential effect of attention on appearance at low contrast. But, due to the small number and asymmetric range of contrasts probed, their experiment was not well designed to test this contrast regime, and I am not confident about their result. For the higher contrasts they tested, the measured effects of attention trended in the opposite direction.