An electrophysiological study of haptic roughness: effects of levels of texture and stimulus uncertainty in the P300.

This study investigated the neural mechanisms implicated in tactile perception using a discrimination task. We also investigated the influence of the type of presentation on the subject's uncertainty. The stimuli varied across four levels of roughness and were presented using a pure/mixed block design. We used an oddball paradigm with three target stimuli varying in the level of roughness, and a smooth surface as the non-target. Stimuli were presented using a specific-purpose device. We analyzed the modulation of the P300 amplitude elicited by targets and non-targets in both presentation conditions. The results showed that the P300 waveform was modulated by roughness, as well as by the order of stimuli presentation. The P300 amplitude was more sensitive to roughness when stimuli were presented in mixed blocks (higher uncertainty). The results are discussed in the context of the attention resources allocation theory applied to tactile modality.