Abstract
Human observers automatically extract temporal contingencies from the environment and predict the onset of future events. Temporal predictions are modelled by the hazard function, which describes the probability for an event to occur over time given it has not occurred yet. To test whether and how the human time-domain EEG signal tracks temporal hazard, we applied an encoding-model approach. In a pitch discrimination task, we implicitly varied the foreperiod (the interval between a cue and a target tone) to induce temporal predictability. We compared conditions in which temporal predictability was either solely driven by the passage of time (resulting in a monotonic hazard function), or was modulated to increase at intermediate foreperiods (resulting in a modulated hazard function with a peak at the intermediate foreperiod). Forward encoding models trained to predict the recorded EEG signal from different temporal hazard functions were able to distinguish between experimental conditions that differed in temporal hazard. Moreover, the supplementary motor area, a key region in timing and time perception, appears as the primary source of the tracking signal in a brain-wide search for neuroanatomical correlates of these encoding models’ response function. Our results underline the utility of the forward-encoding model to understand the neural implementation of abstract mental representations such as temporal hazard.
Significance Statement Extracting temporal predictions from sensory input allows to process future input more efficiently and to prepare responses in time. In mathematical terms, temporal predictions can be described by the hazard function, modelling the probability of an event to occur over time. Here, we show that the human EEG tracks temporal hazard in an implicit foreperiod paradigm. Forward encoding models trained to predict the recorded EEG signal from different temporal-hazard functions were able to distinguish between experimental conditions that differed in their build-up of hazard over time. These neural signatures of tracking temporal hazard converge with the extant literature on temporal processing and provide new evidence that the supplementary motor area tracks hazard under strictly implicit timing conditions.
Footnotes
Conflict of interest: None
