Abstract
We are constantly exposed to multiple visual scenes, and while freely viewing them without an intentional effort to memorize or encode them, only some are remembered. Visual memory is assumed to rely on high-level visual perception that shows a level of cue-invariance, and therefore is not assumed to be highly dependent on physical image cues as size or contrast. However, this is typically investigated when people are instructed to perform a task (e.g. remember or make some judgement about the images), which may modulate processing at multiple levels and thus may not generalize to naturalistic visual behavior. Here I will describe a set of studies where participants (n>200) freely viewed images of different sizes or of different levels of contrast while unaware of any memory-related task that would follow. We reasoned that during naturalistic vision, free of task-related modulations, stronger physical image cues (e.g. bigger or higher contrast images) lead to higher signal-to-noise ratio from retina to cortex and would therefore be better remembered. Indeed we found that physical image cues as size and contrast influence memory such that bigger and higher contrast images are better remembered. While multiple factors affect image memory, our results suggest that low- to high-level processes may all contribute to image memory.