Table 2.

Behavioral ethogram for human intruder task^a

Category and specific behaviors	Measurement	Examples
Affiliative	Cumulative frequency
Lipsmack	Frequency	Rapid movement of pursed lips, accompanied by a smacking sound
Present	Frequency	Rigid posture (knees locked) with tail elevated and rump oriented toward the stimulus object
Anxiety	Cumulative frequency
Scratch	Frequency	Rapid scratch of body with hands or feet
Body shake	Frequency	Shake of the whole body or just head and shoulders region
Tooth grind	Frequency	Repetitive rubbing or chewing of upper and lower teeth
Yawn	Frequency	Open mouth widely, exposing teeth
Fearful	Cumulative frequency
Withdrawal	Frequency	Quick, jerky motion away from the stimulus object (jump back)
Grimace	Frequency	Retracted lips, exposed clenched teeth
Hostile	Cumulative frequency
Cage aggression	Frequency	Slaps, shakes, bites, or slams body against cage
Threat	Frequency	Open mouth (no teeth exposed)
Bark	Frequency	Low pitch, high intensity, rasping, guttural
Lunge	Frequency	A quick, jerky movement toward the stimulus
Position	Duration
Front of cage	Duration	No part of animal's body contacts back of the cage
Back of cage	Duration	Animal's body contacts back of the cage
Stereotypies	Cumulative Duration
Pacing	Duration	Repetitive motor pattern around the test cage
Motor stereotypy	Duration	Repetitive, abnormal voluntary or involuntary motor patterns (e.g. swinging, twirling, flipping)
Stillness	Duration	Motionless posture for at least 3 s (except small head movements)
Vocalizations	Cumulative frequency
Coo	Frequency	Clear soft pitch and intensity, sounds like “ooooh”
Scream	Frequency	High pitch, high intensity screech or loud chirp

^aAdapted from Raper et al. (2019).