More than a metaphor? The distributional history of words in natural language accounts for the direction of different mental time lines

Time can be spatially represented in the human mind according to the sagittal and horizontal directions. So far, the role of sensory-motor experience in the setting of these mental representations has been addressed. Recently, using distributional semantic models, researchers showed that language can encode spatial information. However, to date, no research has specifically examined language’s ability to encode spatial directions of time and its possible influence on mental time lines. To address this gap, the present study aimed to investigate whether language could hide the sagittal and horizontal direction of time, further analyzing the relationship between language experience and the mental organizations of time. In a first computational experiment, we computed the semantic similarity of past, present and future verbs with temporal, sagittal, and horizontal concepts using distributional semantic models. Results showed that language can encode different temporal directions: from past to future, from backward to forward, and from left to right. Successively, two different behavioral tasks were proposed to measure, respectively, the sagittal and the horizontal mental time line. Participants had to judge the tense of 50 Italian verbs conjugated in the future or past tense using forward and backward keys (Experiment 2), or left and right keys (Experiment 3). The semantic closeness of the same verbs to sagittal or horizontal concepts was computed as continuous predictor. Results showed that computational outcomes were significant in predicting behavioral outcomes in both experiments: the closer to the rightward was the verb, the faster were participants in classifying it with the right hand; the closer to the forward was the verb, the faster were participants in classifying it with the forward key. Overall, the present work sheds light on the connection between language and mental representations of time, proposing a common influence of both perceptual and non-perceptual factors on these processes.