- Impulsivity could, therefore, also be tied to welfare. If you are in a better mood, you probably have better welfare, says Laura.
So how do you measure how impulsivity connects to affective state in junglefowl? During her PhD, Laura, along with other researchers in the Løvlie group, tested junglefowl as young chicks, older chicks and adults for positive affective state (specifically optimism), negative affective state (namely stress/fearfulness) and impulsivity. They then looked for links between the affective states and impulsivity.
To test optimism, the researchers used a ‘Cognitive judgement bias test’. First, they trained the fowl to act on two different colored cues, one black bowl and one white bowl. The black had no reward, so approaching it was a waste of time, and the white one had a food reward.
- When the bird has learned these cues we show them a gray bowl. How do they interpret gray? It's a glass half-full situation, says Laura.
The assumption is that the more optimistic junglefowl will approach the gray cue faster, as they are more convinced it will be rewarded. To measure negative affective state, Laura used a test that has been used on chickens since around the 1950s, the ‘Tonic immobility test’. If a red junglefowl is restrained on their back this will trigger an antipredator response and they will freeze, as if playing dead.
- You gently put them on their back, put your hands on them so they can't move, and then slowly remove your hands. The time it takes for them to get out of this frozen state is positively correlated with how fearful/stressed they are in general.
Finally, impulsivity was tested in a ‘Detour test’, where the birds first learn how to get food out of an opaque cylinder. When they know how to do this, they are given a transparent cylinder containing food.
- They now see the food in front of them and there is this automatic, impulsive, response to go straight at it. To reach the food they have to inhibit that impulse and instead use the detour they learned from the opaque cylinder, says Laura.
There were differences in the age groups. In the young chick, high impulsivity was connected to a more positive, less negative, affective state.
- So, in young chicks being more impulsive might lead to a better mood, or perhaps a better mood makes you more impulsive. More research is needed to explore this further. In older chicks and adults, however, we did not find any links between affective state and impulsivity, says Laura Garnham.