Neural correlates of control operations in inverse priming with relevant and irrelevant masks Daniel Krüger a , Susan Klapötke a , Stefan Bode b , Uwe Mattler a, ⁎ a Georg-Elias-Müller Institute for Psychology, Georg-August University Göttingen, Germany b Psychological Sciences, The University of Melbourne, Australia abstract article info Article history: Accepted 5 September 2012 Available online 16 September 2012 Keywords: Priming Negative compatibility effect Consciousness Cognitive control Inhibition The inverse priming paradigm can be considered one example which demonstrates the operation of control pro- cesses in the absence of conscious experience of the inducing stimuli. Inverse priming is generated by a prime that is followed by a mask and a subsequent imperative target stimulus. With “relevant” masks that are composed of the superposition of both prime alternatives, the inverse priming effect is typically larger than with “irrelevant” masks that are free of task-relevant features. We used functional magnetic resonance imaging (fMRI) to examine the neural substrates that are involved in the generation of inverse priming effects with relevant and irrelevant masks. We found a network of brain areas that is accessible to unconscious primes, including supplementary motor area (SMA), anterior insula, middle cingulate cortex, and supramarginal gyrus. Activation of these brain areas were involved in inverse priming when relevant masks were used. With irrelevant masks, however, only SMA activation was involved in inverse priming effects. Activation in SMA correlated with inverse priming effects of individual participants on reaction time, indicating that this brain area reflects the size of inverse priming effects on the behavioral level. Findings are most consistent with the view that a basic inhibitory mechanism contributes to inverse priming with either type of mask and additional processes contribute to the effect with relevant masks. This study provides new evidence showing that cognitive control operations in the human cortex take account of task relevant stimulus information even if this information is not consciously perceived. © 2012 Elsevier Inc. All rights reserved. Introduction Cognitive control has been considered one instance which requires conscious processing (e.g., Norman and Shallice, 1986). However, several studies have shown that the processing of a target stimulus can be influenced by a preceding unconscious prime stimulus (e.g., Neumann and Klotz, 1994; Vorberg et al., 2003). Typically, performance benefits are observed when prime and target belong to the same category (congruent condition) as opposed to alternative categories (incongruent condition). On this background, it is a matter of debate whether unconscious stimuli can also modulate cognitive control operations (e.g., Dehaene et al., 2003; Rees et al., 2002). One instance in which cognitive control is required is the inhibition of automatic responses (e.g., Norman and Shallice, 1986). The inhibition of automatic response activation has been assumed to account for the inverse priming effect (e.g., Eimer and Schlaghecken, 1998). Inverse priming is characterized by performance deficits on congruent trials which can result when a separate masking stimulus is presented between prime and target stim- uli (e.g., Eimer and Schlaghecken, 1998). The size of inverse priming depends on the stimulus onset asynchrony (SOA) between mask and target stimulus (e.g., Mattler, 2007; Schlaghecken and Eimer, 2000) and the structure of the mask (e.g. Lleras and Enns, 2004). With short mask-target SOAs priming effects tend to be positive, with increasing mask-target SOA inverse priming effects occur. As outlined below, it is assumed that this reversal of priming effects with long SOA is linked to increased automatic control processing on congruent trials. With masks that consist of task-relevant features inverse priming effects are typically larger than with masks that consist of irrelevant features. Here we examined the inverse priming paradigm in a functional mag- netic resonance imaging (fMRI) study to determine the automatic con- trol operations in the human cortex which are involved in inverse priming with relevant and irrelevant masks. To account for the modulation of inverse priming effects by the struc- ture of the mask the literature provides at least three different approaches (Krüger et al., 2011). According to the Co-active Mechanisms approach, an inhibitory mechanism is effective with both types of masks and an additional mechanism contributes to the effect with relevant masks (Lleras and Enns, 2006). According to the Single-Mechanism approach, the inhibitory mechanism generates inverse priming effects with both kinds of masks and it is more productive with relevant masks (Jaśkowski and Verleger, 2007). According to the Separate Mech- anisms approach, one mechanism accounts for the entire effect with relevant masks, and a different inhibitory mechanism is only operating with irrelevant masks (Klapp, 2005). Therefore, clear evidence for the NeuroImage 64 (2013) 197–208 ⁎ Corresponding author at: Georg-Elias-Müller Institute for Psychology, Georg-August University Göttingen, Gosslerstr, 14, D-37073 Göttingen, Germany. E-mail address: uwe.mattler@psych.uni-goettingen.de (U. Mattler). 1053-8119/$ – see front matter © 2012 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.neuroimage.2012.09.018 Contents lists available at SciVerse ScienceDirect NeuroImage journal homepage: www.elsevier.com/locate/ynimg