The Stroop effect: Why proportion congruent has nothing to do with congruency and everything to do with contingency.

Abstract

The item-specific proportion congruent (ISPC) effect is the observation that the Stroop effect is larger for words that are presented mostly in congruent colours (e.g., BLUE presented 75% of the time in blue), and smaller for words that are presented mostly in a given incongruent colour (e.g., YELLOW presented 75% of the time in orange). One account of the ISPC effect, the modulation hypothesis, is that participants modulate attention based on the identity of the word (i.e., participants allow the word to influence responding when it is presented mostly in its congruent colour). Another account, the contingency hypothesis, is that participants use the word to predict the response that they will need to make (e.g., if the word is YELLOW, then the response is probably orange). Reanalyses of data from Jacoby, Lindsay, and Hessels (2003) along with results from new experiments are inconsistent with the modulation hypothesis, but entirely consistent with the contingency hypothesis. A response threshold mechanism for using contingency information is proposed and tested. Contingency Learning 3The Stroop Effect: Why Proportion Congruent has Nothing to do with Congruency and Everything to do with Contingency Contingency learning is a lively area of research (e.g., Jacoby, Lindsay, & Hessels, 2003;Musen & Squire, 1993;Schmidt, Crump, Cheesman, & Besner, 2007). One popular domain for this research is the Stroop paradigm. The standard Stroop effect is the finding that participants take longer to identify the print colour of an incongruent colour word (e.g., the word GREEN printed in red; GREEN red ) relative to a congruent colour word (RED red ;Stroop, 1935; see MacLeod, 1991, for a review). The magnitude of the Stroop effect changes when the proportion of congruent items is manipulated (Lowe & Mitterer, 1982). In particular, the Stroop effect increases as the proportion on congruent trials increases. The standard account of the influence of proportion congruent (Cheesman & Merikle, 1986;Lindsay & Jacoby, 1994;Lowe & Mitterer, 1982) is that the detection of these proportions allows participants to modulate attention to the word, thereby changing the size of the Stroop effect. However, Schmidt et al. (2007) suggest that simple contingency learning provides a sufficient account of the proportion congruency effect. Here, we provide a reanalysis of the Jacoby et al. participants use contingency information to control responding will also be considered. Proportion Congruency and the Modulation HypothesisA number of experiments (Cheesman & Merikle, 1986;Lindsay & Jacoby, 1994;Lowe & Mitterer, 1982) have shown that the magnitude of the Stroop effect can be modulated by varying the proportion of congruent trials. Specifically, the Stroop effect is larger when most of the items in the experiment are congruent (high proportion congruent) than when most of the Contingency Learning 4 items are incongruent (low proportion congruent). The standard explanation of this effect (Cheesman & Merikle, 1986;Lindsay & Jacoby, 1994;Lowe ...

The Parallel Episodic Processing (PEP) model: Dissociating contingency and conflict adaptation in the item-specific proportion congruent paradigm

“…The additive pattern of data observed by Schmidt and Besner (2008) is indeed problematic for the conflict adaptation account of the ISPC when observed. However, there is a problem with the prediction that contingency and congruency should always be additive.…”

“…A drastically different interpretation of the ISPC effect (and PC effects in general) was presented by Schmidt and colleagues (Schmidt & Besner, 2008;Schmidt, Crump, Cheesman, & Besner, 2007;see also, Mordkoff, 1996). According to these authors, participants might simply be learning the contingencies between distracting words and responses to the colour.…”

“…In addition, the PEP model will be used to investigate an important question about additivity. Specifically, Schmidt and Besner (2008) argued that contingency and CONTINGENCY AND CONFLICT ADAPTATION 6 congruency effects are due to statistically-independent processes and should generally not interact with each other. This paper will argue that this additivity prediction is mistaken.…”

“…Note that response conflict is still assumed to exist according to the contingency account, but the changes in the size of the Stroop effect with differing levels of PC has to do with the predictive relationships between words are responses and not due to variation in conflict per se. Schmidt and Besner (2008) suggested that participants learn the predictive relationships (i.e., contingencies) between words and responses to prepare for the likely (i.e., high contingency) response. In particular, they suggested that participants calculate the expected response based on the identity of the word and use this response prediction to decrease the response threshold of the predicted response.…”

Proportion congruency and practice: A contingency learning account of asymmetric list shifting effects.

“…Although far from a consensus, some data suggests that simple learning processes may be sufficient to explain "item-specific" (Atalay & Misirlisoy, 2012;Grandjean et al, 2013;Hazeltine & Mordkoff, 2014;Schmidt, 2013c;Schmidt & Besner, 2008), "list-level" (Schmidt, 2013b(Schmidt, , 2014b, and "context-specific" PC effects (Schmidt et al, 2014). The current results suggest that conflict-unrelated learning is also sufficient to explain asymmetric list shifting.…”