Table 1.

Ethogram used to score the behaviours of the pigs during the attention bias test

Behaviour	Definition
Attention class
Attention to the threat	With the head oriented toward the location of the threat
Attention to something else	With the head oriented toward other directions, except threat
Behaviour class
Vigilance	Standing motionless with head at shoulder height or higher or lower
Eating	Eating food in the bucket. The eating event continues, while the pig is chewing provided that the head stays close to the bucket and the pig remains non-vigilant. Once the pig becomes vigilant or moves away from the bucket, this is considered to be the end of eating, even if the pig continues chewing
Exploring	Exploring the floor or wall of the arena by sniffing, nosing, licking or rooting it with the rooting disc
Walking	Walking without performing any other described behaviour. All four legs move or the pig turns around at the same spot without moving all four legs
Standing	Standing with four paws on the floor without performing any other described behaviour
High-pitched vocalizationsa	Screams, squeals, or grunt-squeals
Short grunta	Grunt lasting less than 0.4 s (Fraser 1974; Kiley 1972)
Long grunta	Grunt lasting more than 0.4 s (Fraser 1974; Kiley 1972)
Barka	A low tone that sounds like “wuff”
Defecatinga	Defecating
Urinatinga	Urinating
Escapinga	The pig jumps to the wall or the door

Behaviours were scored as states unless indicated otherwise

^aWere scored as events, all other behaviours as states