2.4. FMRI data acquisition and analysis

The experiment was performed on a 3 Tesla MRI scanner (Magnetom TIM Trio; Siemens Healthcare, Erlangen, Germany). Thirty‐four axial slices parallel to the anterior‐posterior commissure were acquired in ascending acquisition order (slice thickness = 3 mm; gap 20%) using a T2*‐sensitive echo‐planar imaging (EPI) sequence (interscan interval 1,800 ms; echo time 30 ms; flip angle 70°; field‐of‐view 192 mm). A total of 1,527 image volumes were acquired over the course of three functional runs. In the scanner, subjects saw the stimuli through goggles (Resonance Technology, Nothridge, USA) and responded via button presses on a fiber optic computer response device (Current Designs, Philadelphia, USA). Generation of stimuli and triggering of visual stimulation was achieved using the Presentation^® Software (Neurobehavioral Systems, Albany, USA). Functional images were preprocessed and analyzed with SPM 8 (Wellcome Trust Centre for Neuroimaging, University College London, London, UK). At single subject level, each experimental condition was convolved with the hemodynamic response function to form regressors for each individual trial type: trials where a nontarget was paired with a nontarget, nontarget paired with a target, CR paired with a nontarget and CR paired with a target, each both for the nonsalient trials and for the salient trials. The block cues indicating the target stimuli and the block feedback were also modeled as independent regressors, resulting in a total of 10 regressors. Linear t‐contrasts were defined for assessing the specific effects of each condition of interest. Single‐subject contrast images were taken to the second level to assess group effects with random‐effects analyses. Group effects were examined using a full factorial model with the factors saliency (salient trials versus nonsalient trials) and experimental trial type (trials combining nontarget plus nontarget stimulus; nontarget plus target; CR plus nontarget; CR plus target). For detailed information regarding calculated contrasts see Supporting Information.

Statistical effects were determined at a search criterion of p < .005, uncorrected, with a minimum cluster size of 10 voxels, if not otherwise indicated. Corrections for multiple comparisons were performed using family‐wise error (FWE) at p < .05. For brain regions with a priori hypotheses i.e., for the bilateral VTA and vStr (VTA: ±8 −16 −16; 8 mm sphere; vStr: ±12 12 −4; 6 mm sphere, coordinates taken from Diekhof & Gruber, 2010) we used small volume corrections (SVC). To illustrate the magnitude of change due to the influence of salience, means of parameter estimate values for the desire and reason contrast were plotted. For this purpose, the MarsBar software (Brett, Anton, Valabregue, & Poline, 2002) was used to extract each region of interests (ROIs) mean blood oxygenation level‐dependent (BOLD) beta value with a sphere of 6 mm around the reported peak levels for each participant (see Figure 4 and Supporting Information Figure S1).