Upon learning to associate one colour cue (white or black) with a reward and the opposite (black or white) with the lack of a reward the chicks were subjected to the cognitive judgment bias test. With this test the objective was to find out how the chicks interpret their surroundings. The test therefore consisted of investigating if intermediate, grey, cues were experienced as positive or negative. 

This was done by taking away the choice the chick had in the associative learning which you can read more about under the menu to the left. Instead chick were only presented with one colour cue at a time in a predetermined semi-random order. This colour cue was white, black or had a grey gradient of 25 %, 50 % or 75 % in between this previously learned cues. Latencies for the chick to reach each individual cue were measured and compared. As chicks got tired of the test when left in the arena for to long a maximum latency to reach the cue was set. For the laying hen chicks in the environmental experiment this maximum latency was 30 seconds and for the Red Junglefowl chicks in the personality experiment the maximum latency was 60 seconds. 

The idea with this experiment, which has also been seen to work in previous studies (e.g. Harding et al. 2004, Enkel et al. 2010, Wichman et al. 2012 ) is that animals that act as if the intermediate cues are rewarded are optimistic and if they act as they do to the unrewarded cue they are pessimistic. Thus, latencies to reach the intermediate cues similar to those of latencies to reach the rewarded cue is interpreted as optimistic in my study. Furthermore, latencies to reach intermediate cues resembling those to reach unrewarded cues are considered to be pessimistic. 

Enkel T, Gholizadeh D, von Bohlen und Halbach O, Sanchis-Segura C, Hurlemann R, Spanagel R, Gass P & Vollmayr B. 2010. Ambiguous-cue interpretation is biased under stress- and depression-like states in rats.  Neuropsychopharmacology . 35, 1008-1015.

Harding EJ, Paul ES & Mendl, M. 2004. Cognitive bias and affective state. Nature. 427, 312.

Wichman A, Keeling LJ & Forkman B. 2012. Cognitive bias and anticipatory behaviour of laying hens housed in basic and enriched pens. Applied Animal Behaviour Science. 140, 62-69.