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 ...

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Conflict adaptation is one of the most popular ideas in cognitive psychology. It purports to explain a wide range of data, including both brain and behavioural data from the proportion congruent and Gratton paradigms. However, in recent years many concerns about the viability of this account have been raised. It has been argued that contingency learning, not conflict adaptation, produces the proportion congruent effect. Similarly, the Gratton paradigm has been shown to contain several confounds, most notably feature repetition biases. Newer work on temporal learning further questions the interpretability of the behavioural results of conflict adaptation studies. Brain data linking supposed conflict adaptation to the anterior cingulated cortex (ACC) has also come into question, as this area seems to be solely responsive to time-ontask rather than conflict. This review points to the possibility that conflict adaptation may simply be an illusion. However, the extant data remain ambiguous and there are a lot of open questions that still need to be addressed in future research. QUESTIONING CONFLICT ADAPTATION 3 Questioning Conflict Adaptation: Proportion Congruent and Gratton Effects ReconsideredThe role of cognitive control in basic mental functions is one of the primary questions of interest for cognitive psychologists. One of the most popular ideas in the literature is conflict adaptation, the idea that we deal with conflict between stimuli in our environment by shifting attention away from the source of conflict and toward the stimulus we wish to process. The Stroop paradigm (Stroop, 1935) offers the most common way of studying conflict adaptation. In this task, participants identify the print colour of a colour word. Response times and error rates are increased to incongruent stimuli (e.g., the word BLUE printed in red; BLUE red ) relative to congruent stimuli (e.g., BLUE blue ). Other commonly used paradigms included the Eriksen flanker task (Eriksen & Eriksen, 1974), in which congruent or incongruent distracting letters (or words) are presented on either side of a centrally-located target letter (or word); and the Simon task (Simon & Rudell, 1967), in which a distracting stimulus location is either congruent or incongruent with the response that needs to be made to the target (e.g., a left keypress for a stimulus on the right side of the screen). In paradigms such as these, evidence for conflict adaptation comes from the observation that the size of the congruency effect can be altered in response to changes in conflict. In particular, this paper discusses the proportion congruent and Gratton paradigms.Conflict adaptation theory has a lot of explanatory power. However, the goal of this paper is to explore whether or not conflict adaptation must be assumed in order to explain such phenomena as the proportion congruent and Gratton effects. Some of the mounting evidence against the highly popular conflict adaptation account will be discussed and it will be argued that simpler, non-conflict learning and...

The results of four experiments provide evidence for controlled processing in the absence of awareness. Participants identified the colour of a neutral distracter word. Each of four words (e.g., MOVE) was presented in one of four colours 75% of the time (Experiments 1 and 4) or 50% of the time (Experiment 2 and 3). Colour identification was faster when the words appeared in the colour they were most often presented in relative to when they appeared in another colour, even for participants who were subjectively unaware of any contingencies between the words and colours. An analysis of sequence effects showed that participants who were unaware of the relation between distracter words and colours nonetheless controlled the impact of the word on performance depending on the nature of the previous trial. A block analysis of contingencyunaware participants revealed that contingencies were learned rapidly in the first block of trials.Experiment 3 showed that the contingency effect does not depend on level of awareness, thus ruling out explicit strategy accounts. Finally, Experiment 4 showed that the contingency effect results from behavioural control and not from semantic association or stimulus familiarity. These results thus provide evidence for implicit control. Implicit Control 3Contingency Learning without Awareness: Evidence for Implicit Control Cognitive processes that are controlled are conventionally assumed to operate in a slow, effortful, and voluntary manner (Posner & Cohen, 1984;Posner & Snyder, 1975; Shiffrin & Schnieder, 1977). Thus, when researchers discuss the influence of "controlled" processes, it is typically assumed that such processes are explicit (i.e., conscious; cf., Besner & Stolz, 1999). As such, the term "implicit control" would seem to be nonsensical, because "implicit" (i.e., unconscious) seems to preclude the possibility of control. However, etymologically speaking this is not a necessary conclusion. The Oxford English Dictionary (2001) Evidence for cognitive control, which is assumed to be explicit and strategic in nature, has been drawn from the Stroop literature (Stroop, 1935). In the Stroop task, identification of the print colour of colour words is slower when the word and ink colour are incongruent (e.g., the word GREEN in orange; GREEN orange ) than when they are congruent (e.g., ORANGE orange ; see MacLeod, 1991, for a review). Probably the most important demonstration of putatively controlled processes in the Stroop literature is the proportion congruent effect. The proportion congruent effect refers to the finding that the size of the Stroop effect is influenced by the proportion of congruent items in a block of trials (Lindsay & Jacoby, 1994;Logan & Zbrodoff, 1979). Specifically, the Stroop effect is much larger in a high proportion congruent block of trials than in a low proportion congruent block of trials. This effect is commonly attributed to Implicit Control 4 participants explicitly learning to predict the colour from the word. Specifically, because the word us...

The current report presents a temporal learning account as a potential alternative to the conflict adaptation account of list-level proportion congruent effects in the Stroop paradigm. Specifically, retrieval of information about response times on previous trials influences a participant's preparedness to respond at a similar time on following trials. First, an adaptation of the Parallel Episodic Processing (PEP) model is presented, and a list-level effect is produced with a temporal learning mechanism. Next, linear mixed effect model analyses show that temporal learning biases are present in list-level proportion congruent data. A non-conflict experiment is then presented in which a list-level effect is observed with a contrast, rather than congruency, manipulation. Analyses of the experimental and simulated data could not, however, provide a clear picture of whether temporal learning was the sole contributor to the list-level proportion congruent effect. These results do, however, demonstrate that caution is warranted when interpreting list-level proportion congruent effects.