Cognitive control and associative processes in a process dissociation model of the Stroop task with application to list-wide and item-specific proportion congruent effects

• Applicant: Dr. Kerstin Dittrich
• Subject Area: General, Cognitive and Mathematical Psychology
• Term: from 2014 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 265460498

In a seminal study, Lindsay and Jacoby (1994) applied the process dissociation procedure to dissociate word-reading and color-naming processes in the classical Stroop task. To validate the estimated color-naming parameter (C parameter) and word-reading parameter (W parameter), Lindsay and Jacoby manipulated color prototypicality (affecting only the C parameter) and the proportion of congruent and incongruent stimuli (affecting only the W parameter). For the proportion manipulation, smaller interference effects are typically obtained when Stroop stimuli are mostly incongruent; a result pattern that was initially attributed to experiment-wide cognitive control strategies of reduced word-reading processes in case that word reading hinders task performance (i.e., when stimuli are mostly incongruent). However, a new account ascribes proportion congruent effects to an associative-learning mechanism (Schmidt & Besner, 2008). This account postulates that the link of a particular stimulus with a particular response is strengthened when the stimulus is frequently shown (i.e., a proportion congruent manipulation might in fact be a contingency manipulation). Given this new interpretation of proportion congruent effects, it is apparent that Lindsay and Jacoby's interpretation of the W parameter is ambiguous: As long as processes underlying proportion congruent effects are not clear, it cannot be concluded that a change in W parameters caused by a proportion congruent manipulation reflects a change of the impact of word-reading processes on responses. And as long as the processes underlying W parameters are not clear, it cannot be concluded that proportion congruent effects represent cognitive control strategies of modulated word-reading processes by simply showing that varying proportion congruence modulates W parameters. To break out of this vicious circle, we plan to investigate the processes underlying W parameters as well as the processes underlying proportion congruent effects with the help of separable W parameters for congruent and incongruent stimuli. Planned experiments will manipulate cognitive control and associative learning. The impact of these manipulations on the W parameters of congruent and incongruent stimuli will help us to assess the relative influence of cognitive control and associative processes on word-reading parameters and on proportion congruent effects.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr. Karl Christoph Klauer