Table 1 Interoception and social cognition domain assessed and tasks employed

Interoception sensitivity

HBD

The HBD is a motor tracking test that assesses interoception sensitivity. Participants had to tap a key on a keyboard along with their heartbeat in different conditions. First, as a motor-control condition, participants had to follow an audio-recording of a heartbeat. Next, they had to follow their heartbeat without external feedback (intero-pre condition). Then they had to do the same while receiving simultaneous auditory feedback of their own heart provided through online EKG register (feedback condition). Finally, they had to follow their own heartbeat without feedback (intero-post condition). These conditions offer a measure of audio-motoric performance (first condition), and a cardiac interoceptive measure (second and fourth conditions), prior to and after the feedback condition, respectively. During this task we also measured heart rate and heart rate variability to control their possible influence on interoception sensitivity; results showed no differences among groups (see Additional file 2).

Social cognition domain

Task

Description

Emotional recognition

Emotional morphing

This task assesses recognition of six basic emotion expressions and consists of 48 morphing faces randomly presented on a screen (see Additional file 1).

Theory of mind

ToM

This test assesses the emotional inference aspect of the ToM. Consist of 36 pictures of the eye region of a face. Participants chose which of four words best described the person’s thoughts or feelings in each picture.

Empathy

IRI

The IRI is a 28-item self-report questionnaire that separately measures both the cognitive and affective components of empathy.