Meaningless but memorable: Reward associations boost recognition of abstract visual stimuli

Visual word processing engages perceptual and memory-related mechanisms that allow rapid identification of written stimuli. While most research relies on meaningful words, recent work suggests that sublexical visual features-such as character strings-can similarly engage neural processes related to attention and memory. The present study investigated how motivational relevance and the memory status of the stimulus interact to shape recognition memory, as reflected in P300/LPC amplitude modulations. Across two event-related brain potential experiments (N = 48), participants learned associations between meaningless consonant strings and monetary outcomes (gain, loss, or zero outcome) based on either the character combination (Experiment 1) or the font type (Experiment 2). In a subsequent old/new recognition task, we orthogonally manipulated memory status and relevance by presenting both previously learned and novel stimuli. Across both experiments, we observed robust old/new effects in the P300/LPC time window. Critically, gain-old stimuli elicited enhanced P300/LPC amplitudes and higher recognition accuracy-indicating that motivational relevance can strengthen recollection even in the absence of meaning. In Experiment 2, this neural enhancement diminished over time, suggesting a dynamic shift from relevance-driven to familiarity-based memory processes when reinforcement is no longer active. These findings suggest that motivational relevance alone is sufficient to enhance memory performance and neural processing for abstract, nonsemantic stimuli. They also underscore the importance of low-level visual features in sublexical stages of visual word recognition and highlight how the impact of motivational associations may change as recognition strategies adapt over time.