Combined fMRI and eye-tracking evidence on the neural processing of visual ambiguity in photographic aesthetics

Abstract

While visual ambiguity is known to play a central role in modern art, the neural correlates of its processing remain substantially unexplored in the case of aesthetic stimuli. To fill this gap, we combined eye-tracking and functional magnetic resonance imaging (fMRI) to investigate both visual exploration, and the associated brain activity and connectivity, when observing (WO) or evaluating (WE) either ambiguous (AMB+) or non-ambiguous (AMB-) artistic photographic stimuli. These manipulations highlighted more fixations (suggestive of higher loading on exploratory processes) when evaluating compared with observing, and stronger right fronto-parietal and occipito-temporal activity (possibly supporting the resolution of visual ambiguity through attentional reorienting to global vs. local aspects) when processing ambiguous compared with non-ambiguous stimuli. Task-by-stimulus type interaction analyses showed that evaluating ambiguous stimuli was specifically associated with stronger fixation-related activity in the left medial prefrontal cortex, as well as decreased connectivity from this region to its right-hemispheric homologue, possibly supporting in-depth visuospatial analyses of complex visual images. These findings pave the way for future studies addressing the role of visual ambiguity in aesthetic appreciation, as well as the factors that might ease vs. hamper its processing and resolution, and their neural correlates.

Keywords: fMRI; Eye-tracking; Medial prefrontal cortex; Neuroaesthetics; Superior parietal lobule; Visual ambiguity.

Fig. 1

Stimuli examples. The figure depicts selected examples of ambiguous (AMB+) and unambiguous (AMB–) photographs.

Fig. 2

Task-related brain activity. The figure shows the regions that were more strongly activated by observing than evaluating (A; red) or evaluating than observing (B; green) regardless of stimulus type, as well as by ambiguous than non-ambiguous (C; yellow) or non-ambiguous than ambiguous (D; blue) photographs regardless of task (p < 0.05 corrected). Colorbars depict the range of t-values reported in each figure panel, with brightest colors reflecting highest t-values and, accordingly, strongest brain activity.

Fig. 3

Evaluation- and fixation-related brain activity and connectivity. The top figure sector depicts the regions showing a stronger relationship with (implicit) beauty assessment during WO compared with WE task (A; red) or with (explicit) beauty assessment during WE compared with WO task (B; green). The bottom figure sector depicts the left medial prefrontal cluster showing stronger fixation-related activity when evaluating (vs. observing) ambiguous (vs. non-ambiguous) photographs (interaction analysis) (C; yellow) alongside the scatterplot of activity against the number of fixations in the four conditions, as well its right-hemispheric target of decreased connectivity in the same condition (evaluating ambiguous photographs; D; blue). Colorbars depict the range of t-values reported in each figure panel, with brightest colors reflecting highest t-values and, accordingly, strongest brain activity.