Sensorimotor states affect choice in the magnitude judgment of ambiguous durations

66 words) The statistics of the environment seem to exert optimal influence on the organization of functions subserving decision making. In order to make decisions about ambiguous sensory information, predictive coding models suggest that brain generate a template against which to match observed sensory evidence. Here we challenge this notion providing evidence that stochastic choices about the magnitude judgment of visual duration are triggered by bottom-up sensorimotor information. Main Text (1204 words, including acknowledgements and references) The statistics of the environment seem to exert optimal influence on the organization of functions subserving decision making. “Predictive coding” models suggest that whenever a clear outcome is not available, the brain resolves perceptual ambiguity by anticipating the forthcoming sensory environment, generating a template against which to match observed sensory evidence. Accordingly, decisions that we make are often guided by the outcomes of similar decisions made in the past. Nevertheless, everyday life teaches us that higher-level processes, such as voluntary choice, have often proved themselves to be immune to previous experience. Task-irrelevant information may influence behavior, not always orienting decision making toward ecologically optimal deeds. Grounded cognition provided some insight in this direction focusing on the role of the body in cognition, based on widespread findings that bodily states can cause cognitive states and be effects of them. Here we investigate if low-level sensorimotor manipulation affects performance of observers whose attempt to generate magnitude decision about ambiguous durations. To this purpose head turning to the left or to the right space was selectively manipulated in two separated experiments. Lateral head turns are known to reallocate spatial attention in the outside world. Two groups of participants had to judge the duration of a test stimulus as longer or shorter with respect to a reference stimulus, once with their head kept straight (baseline) and once while turning their head. We tested groups’ performance in two separate experiments: one during the temporal encoding/storage of the reference stimulus; the other during the retrieval/comparison of the duration of the reference stimulus with that of the test one (Figure 1a, supplementary method). To create an ambiguous vs. unambiguous temporal outcome the duration’ stimuli were manipulated by using a loglinear temporal distance from the reference. Data analysis of both baseline sessions specified the