Recent reformulations of the Sapir-Whorf hypothesis have shown how labels can guide our thinking in situations of uncertainty, facilitating the identification of objects. We examine whether the effect of labels extends beyond perceptual processes, to help us learn the motoric manipulations required to use novel tools. Exploiting immersive virtual reality, we measured behavioural movement latencies and electrophysiological activity from participants learning to use a range of labeled and unlabeled novel tools. We found that providing a tool with a label reduced the time taken to reach for it, with participants also faster and more accurate when executing the manipulations required to use it. Conversely, labels did not confer any facilitation when the tool was simply moved to another location; participants were slower to grasp a labeled tool when asked to transport it. These findings were also supported by electrophysiological recordings, showing a reduction in sensorimotor beta-band (~30Hz) power when participants were asked to use the labeled tools, but not move them. This modulation of beta activity indicates augmented learning of motor-activity related to tool use within somatosensory regions due to the activation of its lexical representation.These results suggest an extension of the Whorfian hypothesis, such that language not only modulates our thoughts and perceptual processes, but also affects our actions with objects and tools. We propose that labels tune our somatosensory experience and help to memorize body states related to tool use by creating an invariant lexical anchor on which we can build motor learning and experience. Significance StatementLanguage and skilled tool use are pivotal endowments of our species. We investigated the role of tool labels in motor learning and brought behavioural evidence that labels help to learn, remember and perform tool use. This enhancement is reflected in the beta-band power, reflecting augmented sensorimotor processing induced by the labels. The results explain why humans attribute labels to tools: labels not only allow us to communicate about tools and help us to identify their referents, they also enhance their usage. This finding extends the Sapir-Whorf hypothesis that language influences the way we think, to the way we act and blurs the distinction between linguistic and motor processing.

No abstract

It has been proposed that agency disorders found in schizophrenia rely on aberrant processing of prediction error. Overreactivity to nonpertinent prediction errors may lead to the attribution of one's own actions to an external source. When applied to perception, this could explain hallucinations. However, experiments in motor control or perception have mainly suggested deficient prediction errors. Using a novel approach based on the manipulation of temporal delays, 23 patients with schizophrenia, 18 patients with bipolar disorder, and 22 healthy participants performed a pointing task with a haptic device that provided haptic feedback without or with delays, which were processed consciously (65 ms) or unconsciously (15 ms). The processing of prediction errors was measured via the adaptation of the hand trajectory, that is, the deceleration in anticipation of the surface, and its modulation as a function of recent history (stable or unstable sensory feedback). Agency was evaluated by measuring the participants' feeling of controlling the device. Only patients with schizophrenia reported a decrease in the feeling of control following subliminally delayed haptic feedback and adapted deceleration durations following subliminally delayed haptic feedback. This effect was correlated with positive symptoms. The overreactivity to subliminal delays was present only when delays occurred repeatedly in an unpredictable way, that is, with a volatile distribution. The results suggest that small temporal uncertainties that should be held as negligible, trigger an aberrant overreactivity which could account for hallucinations and alterations of the patients' conscious feeling of control. General Scientific SummaryInsignificantly small temporal uncertainties in the perceptual and motor domains are typically ignored. This study reveals that patients with schizophrenia, but not bipolar disorders, overreact to delays of a few milliseconds in the haptic feedback. They inadequately adapt their movements to delays and their feeling of control decreases. These effects correlate with positive symptoms, suggesting that negligible prediction errors may become salient in an aberrant way and may thus disturb agency.