(1) Direct signs: behaviours indicating the visual perception of a stimulus |
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Intermittent fixation towards the stimulus |
Looking past the stimulus |
Head movements towards the stimulus |
Following the movement of a stimulus |
Reaching for the stimulus |
Looking away while reaching the stimulus |
(2) Indirect signs: supportive or confirming behaviours |
Avoiding behaviour |
Change of posture |
Smiling |
Blinking of eyes |
Facial expression |
Stereotypic behaviour |