Figure 1.
Experimental set-up during the visuo-tactile stimulation periods and behavioural experimental design.
(A) Design of the experimental blocks, containing three phases: pre-stimulation test (pre-test), visuo-tactile stimulation and post-stimulation test (post-test). (B) Experimental set-up during the visuo-tactile stimulation period. (C) Behavioural task. Panel C1 shows the staircase procedure followed in Experiment 1, in which two staircases containing morphed images between self and other and differing in their direction of change, were randomly interleaved. Images were presented one after the other, with a random interstimulus interval (ISI) ranging between 0.5 and 1.5 s. For each image participants judged whether the face depicted looked “more like their own face” or “more like the other person’s face”. Panel C2 shows the morphing procedure, the direction of morphing (from “self to other” or from “other to self”) displayed in the two types of movies used, and the participants’ task in Experiment 4.
Figure 2.
Mean percentage of frames perceived to look more like “self” or “other” as a result of the synchronous or asynchronous visuo-tactile stimulation and the timing of the test (pre-test vs. post-test). Positive changes (in green colour) indicate that the % of frames judged as “self” increased because participants accepted as “self-stimuli” morphed pictures that contained a larger % of the other’s face, relative to the pre-test. In contrast, negative changes (in red colour) indicate that the % of frames judged as “self” decreased because participants judged as self-stimuli morphed pictures that contained a smaller % of the other’s face, relative to the pre-test (0 = self, 100 = other).
Table 1.
Mean ratings (± SD) for each questionnaire item, and self-reported valence and arousal across conditions in Experiment 2.
Figure 3.
(A) Mean changes (± SE) in heart rate deceleration and (B) mean changes (± SE) in electrodermal activity (EDA) in response to the threatening and non-threatening object approaching the other’s face, following synchronous and asynchronous stimulation. ** denotes 2-tailed significant differences.
Table 2.
Mean ratings (± SE) for each questionnaire item in Experiment 3.
Figure 4.
Mean ratings (± SE) for each questionnaire item across conditions. Participants rated their level of agreement with the statements using a 7-item Likert scale ranging from “strongly agree” (i.e., +3) to “strongly disagree” (i.e., −3). Significant differences between synchronous and asynchronous stimulation suggest changes in self-face representations as a result of the pattern of visuo-tactile stimulation. * denotes 1-tailed significant differences, and ** denotes 2-tailed significant differences.
Figure 5.
Mean percentage of frames perceived to look more like “self” or “other” as a result of the synchronous or asynchronous visuo-tactile stimulation, the timing of the test (pre-test vs. post-test) and the direction of morphing (“other to self” vs. “self to other”). Positive changes (in green colour) indicate that the % of frames judged as “self” increased because participants accepted as “self-stimuli” morphed pictures that contained a larger % of the other’s face, relative to the pre-test. In contrast, negative changes (in red colour) indicate that the % of frames judged as “self” decreased because participants judged as self-stimuli morphed pictures that contained a smaller % of the other’s face, relative to the pre-test (0 = self, 100 = other).