Fig 1.
(a) Protocol for Experiment 1. In each trial, the fixation point was presented for 1,000 ms. The IAPS picture was then presented for 6,000 ms. Each trial was separated by a response period and an inter-stimulus interval (ISI) of 5,000 ms in total. Participants responded to the task in each block following the stimulus presentation using the keypad. (b) Protocol for Experiment 2. The paradigm (presentation times, participants’ tasks, and the number of trials) was identical with that in Experiment 1. However, IADS sounds and not IAPS pictures were used.
Fig 2.
(a) Mean rates at which the participants’ responses to the pictures and sounds in the emotional task matched the valence of the pictures and sounds in Experiment 1 and 2. (b) Detection rates of the target dot and beep sound for the visual task and the auditory task, respectively, in both experiments. The error bars indicate the standard error of the mean across the participants. Asterisks in (a) indicate a significant difference based on multiple comparisons for the main effect of stimulus; * p < 0.05, ** p < 0.01.
Fig 3.
The grand-averaged time course of pupillary responses to the IAPS pictures (positive, negative, and neutral) in the task conditions during the stimulus presentation in Experiment 1.
The horizontal axis indicates the time (s), while the vertical axis indicates the grand-averaged change in pupil dilation from baseline (−200 ms to 0 ms).
Fig 4.
The grand-averaged time course of pupillary responses to the IADS sounds (positive, negative, and neutral) in the task conditions during the stimulus presentation in Experiment 1.
The horizontal axis indicates the time (s), while the vertical axis indicates the grand-averaged change in pupil dilation from baseline (−200 ms to 0 ms).
Fig 5.
The velocity of pupil dilation.
(a) Gradient values of the pupillary response to the IAPS pictures for each condition in Experiment 1. (b) Gradient values of the pupillary response to the IADS sounds for each condition in Experiment 2. Error bars show standard error of the mean across the participants. Asterisks in (b) indicate a significant difference based on multiple comparisons for the interaction between the stimulus condition and the task condition; * p < 0.05, ** p < 0.01, *** p < 0.005.