Suggestion overrides the Stroop effect in highly hypnotizable individuals
Introduction
Cognitive psychologists generally agree that mental processes come in two varieties: controlled and automatic (Shiffrin & Schneider, 1977). Some processes are thought to be innately automatic; others become automatic through practice (Spelke, Hirst, & Neisser, 1976). General accounts posit that once automatized, these processes are initiated unintentionally, effortlessly, even ballistically, and cannot be easily interrupted or prevented. While most researchers who are interested in automatic processes focus on the nature of automaticity and how a process becomes automatic, they have given little or no attention to whether one can regain control over a process that had been automatized. Despite its theoretical and clinical importance, the latter question is not only unanswered, but mostly unasked. The present study examined whether we can “unring” the proverbial bell (i.e., regain control over an ostensibly involuntary process). We report how a posthypnotic suggestion administered to highly hypnotizable individuals can override a process that has become automatized through practice (i.e., reading), and discuss the theoretical and applied implications of our findings.
Reading words is considered an automatic process; a proficient reader cannot withhold accessing word meaning despite explicit instructions to attend only to the ink color. The Stroop task provides evidence for the automaticity of reading: in responding to the ink color of an incongruent color word (e.g., the word “GREEN” inked in red), participants are usually slower and less accurate than in identifying the ink color of either a neutral or congruent word (e.g., “LOT” or “RED” inked in red) (Stroop, 1935). The difference between incongruent and congruent stimuli—the Stroop effect—is one of the most robust and well-studied phenomena in attentional research (MacLeod, 1991, MacLeod and MacDonald, 2000). The standard account posits that words are processed automatically to the semantic level and that the Stroop effect is the “gold standard” of automated performance (MacLeod, 1992).
A few meditative practices claim to achieve “de-automatization” (Dillbeck, 1982) with some sparse evidence of reduced Stroop interference (Alexander et al., 1989, Wenk-Sormaz, 2005). In addition, a number of studies have independently challenged the robustness of the Stroop effect showing either decrease or elimination of Stroop interference (Besner, 2001, Besner and Stolz, 1999a, Besner and Stolz, 1999b, Besner and Stolz, 1999c, Besner et al., 1997, Dishon-Berkovits and Algom, 2000, Melara and Algom, 2003, Pansky and Algom, 2002). Although critiqued (Neely & Kahan, 2001), interpretation of these and other findings of either reduction (Long & Prat, 2002) or removal (Kuhl & Kazén, 1999) of Stroop conflict contends that rather than being inevitable, other factors (e.g., attention, memory, and affect) may govern automatic processing. These findings suggest that a seemingly automatic process can be derailed.
Drawing on a larger sample, the present study provides a replication of our previous results and addresses the following question: Is it possible to regain control over a process that has been automatized? To answer this query, we drew on data from multiple experiments showing that a suggestion to experience Stroop words as meaningless symbols can modulate the Stroop effect in highly hypnotizable individuals—about 10–15% of the adult population who can be reliably identified as highly compliant with hypnotic suggestion using standardized scales (Comey and Kirsch, 1999, Kirsch et al., 1999, Kirsch et al., 1993, Shor and Orne, 1962, Weitzenhoffer and Hilgard, 1962). This approach (Raz, Shapiro, Fan, & Posner, 2002) was reported in a series of studies employing hypnotic suggestions (Egner et al., in press) and consequently extended to a posthypnotic suggestion—a suggestion made during hypnosis indicating that a particular experience or behavior will occur on cue following termination of the hypnotic session (Raz, 2004, Raz, Fan, et al., 2005, Raz et al., 2003, Raz et al., 2002)—and was recently replicated in an independent laboratory (Raz, Kirsch, Pollard, & Nitkin-Kaner, 2006). However, since this notion and findings were first reported in the clinical literature (Raz and Shapiro, 2002, Raz et al., 2002), it may have been missed by the cognitive scientists who would be most interested in it. Here, we report behavioral data from a larger sample of highly hypnotizable persons, discuss the findings in light of our recent neuroimaging data, and outline the potential implications of overriding an automatic process for cognitive neuroscience.
Section snippets
Participants
Participants were 49 right-handed proficient readers of English (24 female) aged 20–35 (mean = 27) years. All participants were recruited from a pool of about 350 volunteers who had been screened for suggestibility in a hypnotic context using both the Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS:A), (Shor & Orne, 1962) and then the Stanford Hypnotic Susceptibility Scale, Form C, (SHSS:C) sans the anosmia to ammonia challenge (Weitzenhoffer & Hilgard, 1962). All participants
Results
Table 1 shows mean reaction times (RTs) and accuracy scores as a function of suggestion and Stroop congruency conditions (congruent, neutral, or incongruent). As in previous assays, administration order was not significant and the data were accordingly collapsed. Incorrect responses were excluded from the RT analyses, as were latencies that were 3 standard deviations either above or below the mean per Stroop condition per participant. About 2% of the data were excluded due to such deviant RTs.
Discussion
Consistent with previous research (Raz, 2004, Raz, Fan, et al., 2005, Raz et al., 2003, Raz and Shapiro, 2002, Raz et al., 2002), our findings indicate that a specific suggestion to construe words as meaningless symbols of an unknown foreign language substantially reduces the Stroop effect in highly hypnotizable individuals. This finding indicates that cognitive processes that had been automatized through practice can be de-automatized and brought under cognitive control.
Examination of the
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2020, Addictive Behaviors ReportsCitation Excerpt :During suggestion the participant is given instructions to experience specific changes in physical or psychological sensations. Most pertinent to the current study, several studies have reported that hypnotic suggestion improves attentional performance on the classic Stroop task, as well as other cognitive tasks (Augustinova & Ferrand, 2012; Iani, Ricci, Baroni, & Rubichi, 2009; Iani, Ricci, Gherri, & Rubichi, 2006; Parris & Dienes, 2013; Parris, Dienes, Bate, & Gothard, 2014; Raz & Campbell, 2011; Raz et al., 2003; Raz, Kirsch, Pollard, & Nitkin-Kaner, 2006; Raz, Moreno-Íñiguez, Martin, & Zhu, 2007; Raz, Shapiro, Fan, & Posner, 2002; Terhune, Cleeremans, Raz, & Lynn, 2017; Virta, Hiltunen, Mattsson, & Kallio, 2015). From a cognitive perspective, hypnotic suggestion has been described as a “unique form of top-down regulation” that can diminish the power of task irrelevant distractors to disrupt performance (Terhune et al., 2017).
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2018, Acta PsychologicaCitation Excerpt :The inability to prevent the irrelevant colour word from interfering with colour naming has been taken as evidence for word reading being an automatic (happening without intent and not requiring attentional resources) and ballistic (cannot be stopped once started) (Brown, Gore, & Carr, 2002; Neely & Kahan, 2001; Posner & Snyder, 1975). However, the demonstration that Stroop interference can be reduced using manipulations such as the narrowing of spatial attention (e.g. Besner, 2001; Besner, Risko, & Sklair, 2005; Besner, Stolz, & Boutilier, 1997; Labuschagne & Besner, 2015; Stolz & McCann, 2000) social priming (Goldfarb, Aisenberg, & Henik, 2011) and a post-hypnotic suggestion (e.g. MacLeod & Sheehan, 2003; Parris, Dienes, & Hodgson, 2012; Raz & Campbell, 2011; Raz, Kirsch, Pollard, & Nitkin-Kaner, 2006; Raz, Moreno-Íniguez, Martin, & Zhu, 2007; Raz, Shapiro, Fan, & Posner, 2002; Raz et al., 2003) has been taken as evidence against the notion that word reading is automatic. In their reviews of the studies above, Augustinova and Ferrand (2014a) and Flaudias and Llorca (2014) pointed out that Stroop interference is made up of both semantic and response based processes.
Brain correlates of hypnosis: A systematic review and meta-analytic exploration
2017, Neuroscience and Biobehavioral ReviewsEliminating stroop effects with post-hypnotic instructions: Brain mechanisms inferred from EEG
2017, NeuropsychologiaCitation Excerpt :Therefore, the apparently stronger reduction of the Stroop effect in the present study may not indicate a true superiority of the present procedure but merely their equivalence. Nevertheless, there seems to be an interesting qualitative difference between the effects of the post-hypnotic instructions used by Raz et al. (2007) and ours. In their study, the mean RTs in the neutral condition were faster by 35 ms when post-hypnotic instructions were present than when there were no instructions.
Structural and functional correlates of hypnotic depth and suggestibility
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2014, Consciousness and Cognition