On how impulsivity can affect responses in cognitive tests of laying hens

E.N. de Haas, T.B. Rodenburg

Research output: Chapter in Book/Report/Conference proceedingAbstract


Impulsivity is defined as the inability to wait before responding. In cognitive tests, subjects often need to associate a cue with an outcome. When an animal is unable to withhold its response due to high impulsiveness, its choice could be wrongly attributed to its cognitive (in)ability.
Moreover, low levels of serotonin (5-HT) seem to underlie impulsivity. We hypothesized that cognitive performance is reduced with high impulsivity and low whole-blood 5-HT levels in chickens. Two experiments were conducted where White Leghorn laying hens needed to associate cue with reward in a two choice set-up and withhold responding. Ten sessions per day with maximum of five training days were performed per test. Hens were socially housed in groups of ten. Cognitive performance and impulsivity of hens with higher and lower than
average levels of whole-blood 5-HT (measured once at adult age) were compared with repeated ANOVA and t-tests. Data expressed at means ± SEM. Correlation analysis of response latency and cognitive performance was conducted, expressed as regression coefficient. In the first experiment (n=36), hens cognitive performance was assessed by the number of incorrect choices. Response latencies were related to these. We found that hens with low 5-HT made more errors than hens with high 5-HT (25 to 40 vs less than 18% incorrect choices: F1,96=5.5, P=0.03). A high number of errors correlated to short response latencies (r=- 0.3, P=0.005). In the second experiment (n=16, training 5 days), hens reversal learning and impulsivity was measured. In a discount-delay test, hens needed to withhold their response otherwise their choice would be unrewarded. Delays were in progressive ratio, amended to the hens ability to
withhold responding. During the reversal test, hens with low 5-HT made more errors than hens with high 5-HT(79 vs 87% average correct choices, t=2.2, P=0.04). Hens with low 5-HT could not wait as long as hens with high 5-HT before switching to the unrewarded feeder (maximum inhibition time: 4.4±0.3 vs 5.8±0.6 s, t=2.12, P=0.05). Our results show that, in laying hens, fast
responses could cause errors in cognitive tests, which may derive from impulsivity as affected by low levels of 5-HT. To establish whether these relationships are causal, 5-HT levels should be modified experimentally and effects on impulsivity and cognitive ability should be investigated.
Original languageEnglish
Title of host publicationProceedings of the 50th congress of the International Society for Applied Ethology
Subtitle of host publicationStanding on the shoulders of giants
EditorsCathy Dwyer, Marie Haskell, Victoria Sandilands
Place of PublicationWageningen
PublisherWageningen Academic Publishers
ISBN (Electronic)9789086868339
ISBN (Print)9789086862870
Publication statusPublished - 2016
Event50th International Congress, Edinburgh, United Kingdom - Edinburgh, United Kingdom
Duration: 12 Jul 201615 Jul 2016
Conference number: 50


Conference50th International Congress, Edinburgh, United Kingdom
Abbreviated titleISAE2016
CountryUnited Kingdom
Internet address

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