Downloads & Free Reading Options - Results

This study investigates whether reward-conditioned stimuli influence attention, motivation, and action selection implicitly. Specifically, we examine Pavlovian-to-Instrumental Transfer (PIT), an effect by which reward conditioned stimuli (CS)s influence instrumental behavior, leading to increased responses toward reward-related cues. Additionally, we assess attentional responses towards reward-conditioned stimuli using an Emotional Attentional Blink (EAB) task, in which CS can overcome attentional distraction by emotionally salient distractors. Importantly, we will use a state-of-the-art Bayesian procedure to determine participants’ awareness of stimulus-outcome contingencies. This will allow to examine whether PIT effects, and attention to high reward CS overcoming aversive distractors in the EAB, can occur implicitly in individuals who are unaware of the contingencies. Finally, we will explore whether these effects are more pronounced in individuals with risky alcohol use. Before the experimental tasks, all participants will complete the Alcohol Use Disorder Identification Test (AUDIT) to categorise participants into high-risk and low-risk alcohol use groups. The experiment consists of three phases: - First, in the Pavlovian reward-conditioning task, geometric shapes (octagon and square) are associated with an 80% probability of earning different reward magnitudes (conditioned stimuli of 10 cents or 50 cents, hereafter CS10 and CS50) and a 20% probability of earning no reward. The assignment of rewards to shapes is counterbalanced across participants. Participants are instructed only to identify the yellow or green color overlaid on the shapes by pressing the left or right key and that they possibly win a monetary reward. No mention is made of the role of the geometric shapes, ensuring that learning of reward contingencies remains implicit. In the Pavlovian phase, 25% of trials include an additional question where participants estimate the potential winnings (10 cents or 50 cents) associated with the shape and rate their confidence on a scale from 1 (no idea) to 5 (very sure). These expectancy measures will be used to differentiate participants who consciously identify the reward contingencies from those who remain unaware. This will allow us to investigate evidence for implicit reward conditioning. - Next, in the Instrumental task, participants engage in a response-contingent reward-learning process, where they repeatedly press a designated key (R10 or R50, corresponding to the left and right arrow keys) to receive a monetary reward. Specifically, pressing the R10 key results in a 50% probability of receiving 10 cents, while pressing the R50 key results in a 10% probability of receiving 50 cents. To ensure the utility of each response option is equivalent, the assignment of rewards to keys is counterbalanced across participants. To reinforce learning and encourage continued engagement, participants are required to press their chosen key multiple times within a trial. The task includes a designated response window that begins randomly between 1.5 and 2.5 seconds after trial onset and lasts for 1 second. During this window, participants must press the same key at least twice for the response to be considered valid. This ensures participants engage actively during the trial rather than relying on single, late responses. If multiple keys are pressed or if the key is pressed fewer than two times in the response window, the trial is marked invalid, and no feedback is given. When a valid response is made, the screen displays the reward (e.g., “you win 10p” or “50p”), reinforcing the response–reward association. - Finally, in the Transfer phase, participants are presented with a sequence of rapidly displayed abstract images in the so-called Rapid Serial Visual Presentation (RSVP) task. Each trial consists of a RSVP of 17 stimuli, each displayed for 95 ms. Embedded within this sequence is a single neutral or aversive distractor image and a target CS (e.g., a geometric shape). Fillers are squares, hexagons and octagons combined into one shape and appear at the beginning of the trial. Aversive or neutral distractors appear on the 4th, 6th or 8th position of the series, followed by another filler and the presentation of the target. Finally, more fillers are presented to complete the stream of 17 images. Examples of aversive images are pictures of certain objects (guns or knives), animals (predators or poisonous animals) or violent scenes (fights, aggressions or mutilated bodies). The target CS are shapes participants previously encountered during the Pavlovian conditioning phase, where each shape (square and octagon) was associated with a specific monetary reward (e.g., 10 cents or 50 cents). A hexagon shape is included as a control condition, always linked to no reward. Thus, there are three target CS (square, hexagon, octagon), each linked to a different outcome: 10 cents, 50 cents, or no reward. After each RSVP sequence, participants either complete the Instrumental task before identifying the target stimulus or identify the target stimulus before completing the Instrumental task. This order is counterbalanced between blocks (3 blocks of 48 trials) to control for any sequence effects. This phase measures the extent to which conditioned stimuli influence action selection (instrumental response, PIT effect) and attentional capture (target stimulus detection accuracy). The study will determine whether these effects occur independently of contingency awareness and whether stronger PIT effects, and a greater ability to overcome attentional capture by aversive distractors during CS50 trials, serve as risk markers for problematic alcohol use.