Which comes first? Examining breaking continuous flash suppression time of high-calorie and low-calorie foods

Food is indispensable in our daily life, as food provides us with energy and consequently is highly correlated with our metabolic and visual systems. Previous studies showed that people unknowingly complete tasks related to calorie evaluation and prefer high-calorie foods to low-calorie foods, suggesting that caloric information can be processed automatically. However, there is still a gap between automatic processes and unconscious processes. The present study aimed to investigate whether food information can be processed without visual awareness. In the series of experiments, we adopted the breaking continuous flash suppression (b-CFS) paradigm to investigate if the time for high-calorie and low-calorie food to access awareness differ. By adopting both food pictures and their corresponding two-character Chinese words as targets, Experiment 1 showed that high-calorie food pictures broke CFS faster than low-calorie food pictures, whereas the opposite pattern was found for high-calorie and low-calorie words, suggesting that the mechanisms of unconscious processing in pictures and words are different. Experiment 2 used diffeomorphic transformed pictures, where pictures are distorted but preserves all visual features, from Experiment 1 as targets. The results showed that the b-CFS times did not differ between high-calorie and low-calorie transformed pictures, suggesting that low-level features in the pictures did not contribute to the difference of b-CFS times across calories in Experiment 1. Furthermore, we also showed that the results in Experiment 1 were free from response bias, as detection times for high-calorie food and low-calorie food were similar in the binocular viewing condition. Together, our results showed that meanings of pictures and words can both be processed unconsciously, suggesting high-level information can survive under CFS.