A Screen-Peck Task for Investigating Cognitive Bias in Laying Hens

Abstract

Affect-induced cognitive judgement biases occur in both humans and animals. Animals in a more negative affective state tend to interpret ambiguous cues more negatively than animals in a more positive state and vice versa. Investigating animals’ responses to ambiguous cues can therefore be used as a proxy measure of affective state. We investigated laying hens’ responses to ambiguous stimuli using a novel cognitive bias task. In the ‘screen-peck’ task, hens were trained to peck a high/low saturation orange circle presented on a computer screen (positive cue–P) to obtain a mealworm reward, and to not peck when the oppositely saturated orange circle was presented (negative cue–N) to avoid a one second air puff. Ambiguous cues were orange circles of intermediate saturation between the P and N cue (near-positive–NP; middle–M; near-negative–NN), and were unrewarded. Cue pecking showed a clear generalisation curve from P through NP, M, NN to N suggesting that hens were able to associate colour saturation with reward or punishment, and could discriminate between stimuli that were more or less similar to learnt cues. Across six test sessions, there was no evidence for extinction of pecking responses to ambiguous cues. We manipulated affective state by changing temperature during testing to either ~20°C or ~29°C in a repeated measures cross-over design. Hens have been shown to prefer temperatures in the higher range and hence we assumed that exposure to the higher temperature would induce a relatively positive affective state. Hens tested under warmer conditions were significantly more likely to peck the M probe than those tested at cooler temperatures suggesting that increased temperature in the ranges tested here may have some positive effect on hens, inducing a positive cognitive bias.

Examining affective structure in chickens: valence, intensity, persistence and generalization measured using a Conditioned Place Preference Test

“…These findings are consistent with the use of both these stimuli as punishers in previous experimental studies (e.g. see Davies et al, 2015 ; Deakin et al, 2016 ; Edgar et al, 2012 , 2013 ; Zimmerman et al, 2011 ), and also consistent with findings from other species such as rats (e.g. see Browning et al, 2017 ).…”

A cross-species judgement bias task: integrating active trial initiation into a spatial Go/No-go task

“…One explanation for this result might be the relatively high ratio of reference trials to ambiguous trials (50:3) within a test session. A similar result was shown in a study by Deakin and colleagues 43 on laying hens with a ratio of reference trials to ambiguous trials of 40:6 within a session. As we had rewarded go responses in ambiguous trials while Deakin et al .…”

Mood As Cumulative Expectation Mismatch: A Test of Theory Based on Data from Non-verbal Cognitive Bias Tests

“…a change in environment such as providing enrichment (shredded paper nesting material, Burman et al, 2008 ; perches, Matheson et al, 2008 ; attractive items in respect to playing behavior, Keen et al, 2014 ), increasing space allowance (animals housed in a multilevel caging system, Wheeler et al, 2015 ), introducing predictable housing conditions (light signal before food, Destrez et al, 2014 ), or increasing thermal comfort (animal under high temperature, Deakin et al, 2016 ),…”