Dual mechanisms governing reward-driven perceptual learning

Abstract

In this review, we explore how reward signals shape perceptual learning in animals and humans. Perceptual learning is the well-established phenomenon by which extensive practice elicits selective improvement in one’s perceptual discrimination of basic visual features, such as oriented lines or moving stimuli. While perceptual learning has long been thought to rely on ‘top-down’ processes, such as attention and decision-making, a wave of recent findings suggests that these higher-level processes are, in fact, not necessary. Rather, these recent findings indicate that reward signals alone, in the absence of the contribution of higher-level cognitive processes, are sufficient to drive the benefits of perceptual learning. Here, we will review the literature tying reward signals to perceptual learning. Based on these findings, we propose dual underlying mechanisms that give rise to perceptual learning: one mechanism that operates ‘automatically’ and is tied directly to reward signals, and another mechanism that involves more ‘top-down’, goal-directed computations.

Ventral midbrain stimulation induces perceptual learning and cortical plasticity in primates

“…Since then, VPL of unattended stimuli has been demonstrated in a variety of paradigms utilizing different controls of stimulus attention and varying sources of reinforcement 17,55–57 . This line of evidence has led to the theory that task-irrelevant VPL can be driven solely by reinforcement signals, generated internally or externally, and that VPL may share the same neural mechanisms underlying classical conditioning 58 . Elegant optogenetic studies in rodents have shown that appetitive conditioning occurs when VTA dopamine neuron activation is temporally coupled with a sensory stimulus 59,60 .…”

Elevated arousal levels enhance contrast perception

“…To experimentally manipulate arousal, we adapteda liquid reward-delivery paradigm commonly used in incentivized learning tasks (Imai, Kim, Sasaki, & Watanabe, 2014;Kim, Ling & Watanabe, 2015;O'Doherty et al, 2002;O'Doherty et al, 2004;O'Doherty, Dayan, Friston, Critchley, & Dolan, 2003;Seitz, Kim, & Watanabe, 2009). Such rewards have previously been shown to have both incentivizing and arousing properties (Bijleveld, Custers, & Aarts, 2009;Bray, Rangel, Shimojo, Balleine, & O'Doherty, 2008;Das, 2015).…”

Only cortical prediction error signals are involved in visual learning, despite availability of subcortical prediction error signals

“…VPL is primarily associated with alterations in visual processing including area V1 and is essential for understanding visual plasticity [8][9][10][11] . Like other types of learning and memory, a key aspect of VPL is its significant improvement through rewards [12][13][14][15][16][17][18][19] . However, the role of reward prediction error (RPE) in VPL remains unclear.…”