Subsidiary analysis of different Stroop-embedded negative priming trials.

In his commentary, MacLeod (2011) presents a rich testing ground for elucidating how suggestion may operationalize attention. The effects of posthypnotic suggestions on Stroop performance raise theoretical questions regarding the nature of the underlying mechanisms. Beyond the methodological designs outlined by MacLeod, one way to address these questions is to examine data from embedded Stroop conditions. Negative priming (NP), for example, is an especially attractive methodology to use in the context of atypical attention because paired stepwise trials are inherently less susceptible to ulterior strategies, which could potentially minimize the Stroop effect (Raz & Campbell, 2011). Researchers can use NP as a complementary vehicle to elucidate findings (e.g., in a post-hoc fashion) or as a primary means of analysis within a sufficiently powered Stroop context specifically designed to explore such trials. In this paper we demonstrate that a meticulous exploration of the nuanced components comprising individual NP sub-effects sketches an experimental blueprint to guide future studies, especially when coupled with additional objective measures (e.g., eye-tracking and imaging of the living human brain). Cognitive inhibition refers to an active process of suppressing irrelevant information, usually from working memory. Cognitive neuroscientists identify the prefrontal cortex as the primary locus of inhibition and distinguish it from susceptibility to interference, which occurs under conditions of multiple distracting stimuli, such as the Stroop task and dual-task performances (Harnishfeger, 1995). NP is an important form of cognitive inhibition and Tipper (1985) introduced the term ‘‘negative priming’’ to refer to the inhibitory effect of ignored stimuli. NP is a form of cognitive inhibition operationalized as the extent to which a subject may inhibit attention resources to distracting stimuli while focusing these resources on a target stimulus. Although cognitive inhibition, or at least the construct of NP, could be an important mechanism in determining hypnotic responsiveness, other forms of inhibition (e.g., cognitive inhibition at retrieval, behavioral inhibition, neurophysiological inhibition) may also contribute to hypnotic responsiveness. Inhibitory tasks, such as NP, may aid in elucidating the relationship between cognitive inhibition and hypnotic responding (David & Brown, 2002; David, King, & Borkardt, 2001). These studies report significant correlations between cognitive inhibition (as assessed by NP in a semantic categorization task) and different measures of hypnotic suggestibility. Hypnotizability, for example, positively correlates with reaction time for ignored stimuli, indicating that suggestibility relates to an ability to inhibit task-irrelevant stimuli. Thus, cognitive inhibition may play a role in hypnotic responding (David & Brown, 2002). Westberry (1983) showed that, in contrast with lows, individuals scoring high on the Tellegen Absorption Scale (Tellegen & Atkinson, 1974) elicited substantial NP. Because absorption correlates with hypnotizability (cf. Kirsch, 1990; Tellegen & Atkinson, 1974) NP may also correlate with hypnotic responsiveness. A relation between the size effect of NP