Intertrial priming of pop-out search influences the shift, skew, and dispersion of response time distributions.

Priming of pop-out (PoP), or intertrial priming, is the finding that responding to a singleton target is faster when a target's defining feature (e.g., color) and nontarget features are repeated between trials than when the target and nontarget features switch between trials. Facilitated responding may reflect priming's influence on selection, that is,  implicitly encoded features speed the selection of a matching target. In contrast, PoP effects may also reflect intertrial priming's influence on postselection processes, where episodic retrieval of a previous target is facilitated when its features match the current target. Lamy, Yashar, and Ruderman Attention, Perception, & Psychophysics, 73, 2160-2167 (2011) proposed a hybrid, dual-stage model that assumes intertrial priming influences both selection and postselection retrieval. To provide support for intertrial priming influencing more than one cognitive process, we examined priming's influence on the shift, skew, and dispersion of RT distributions in PoP tasks by fitting the exponential-Gaussian function to the RTs. Three experiments demonstrated that PoP effects at the level of mean RT were associated with changes in both the shift and skew of the underlying RT distributions. Importantly, Experiments 2 and 3 showed that manipulations intended to influence selection or postselection processes produced corresponding changes in the contributions of the distribution shift and skew to the PoP effects on mean RT. The results suggest more than one process is influenced by intertrial priming in visual search tasks, but readers should be cautious about relating specific processes to specific exponential-Gaussian parameters.