Abstract
The current study examined the influence of expected value on early visual processing. Such early processing can be indexed by the C1, an event-related potential component elicited by the initial processing of visual stimuli and generated from V1. C1 has been assumed to mark activity moving in a feedforward manner through the sensory pathway. Previous literature thus claims that C1 is invariant to top-down influences, such as perceptual or emotional salience. However, recent evidence suggests that C1 can be modulated by such top-down influences. In these cases, stimuli used to elicit C1 are usually inherently meaningful (i.e. emotional faces) and therefore of an uncontrolled value. Thus, it is not clear whether stimulus valence, salience, or a combination of the two alters early sensory processing. This study aimed to address this question by imbuing stimuli with value varying in valence and probability of occurrence. Animal studies suggest that learned reward and loss values are encoded by distinct neuron populations in the amygdala (Paton et al., 2006) that could in turn influence V1 activity through amygdalate-cortical pathways (Amaral & Price, 1984). Thus, it is hypothesized that valence will modulate C1 regardless of probability. Participants first encountered novel faces in a choice task involving winning and losing money (Raymond & O'Brien, 2009) to acquire expected values, combining high and low probability with reward and loss outcomes. Learned faces were then presented in a perceptual discrimination task where participants judged the direction of tilt (45 degrees right or left). Contrary to our hypothesis, in a sample of 20 participants, the C1 elicited to the appearance of the face was modulated by probability regardless of valence, being smallest to high-probability faces and largest to low-probability faces. Results suggest that expected value in the form of probability can modulate early sensory processing in V1.
Meeting abstract presented at VSS 2016