Limits...
Opposite Effects of Early-Life Competition and Developmental Telomere Attrition on Cognitive Biases in Juvenile European Starlings.

Bateson M, Emmerson M, Ergün G, Monaghan P, Nettle D - PLoS ONE (2015)

Bottom Line: We predicted that starlings from larger broods, specifically those that had experienced more nest competitors larger than themselves would exhibit reduced expectation of reward, indicative of a 'pessimistic', depression-like mood.Thus, increased competition in the nest and poor current somatic state appear to have opposite effects on cognitive biases.Our results lead us to question whether increased expectation of reward when presented with ambiguous stimuli always indicates a more positive affective state.

View Article: PubMed Central - PubMed

Affiliation: Centre for Behaviour & Evolution and Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom.

ABSTRACT
Moods are enduring affective states that we hypothesise should be affected by an individual's developmental experience and its current somatic state. We tested whether early-life adversity, induced by manipulating brood size, subsequently altered juvenile European starlings' (Sturnus vulgaris) decisions in a judgment bias task designed to provide a cognitive measure of mood. We predicted that starlings from larger broods, specifically those that had experienced more nest competitors larger than themselves would exhibit reduced expectation of reward, indicative of a 'pessimistic', depression-like mood. We used a go/no-go task, in which 30 starlings were trained to probe a grey card disc associated with a palatable mealworm hidden underneath and avoid a different shade of grey card disc associated with a noxious quinine-injected mealworm hidden underneath. Birds' response latencies to the trained stimuli and also to novel, ambiguous stimuli intermediate between these were subsequently tested. Birds that had experienced greater competition in the nest were faster to probe trained stimuli, and it was therefore necessary to control statistically for this difference in subsequent analyses of the birds' responses to the ambiguous stimuli. As predicted, birds with more, larger nest competitors showed relatively longer latencies to probe ambiguous stimuli, suggesting reduced expectation of reward and a 'pessimistic', depression-like mood. However, birds with greater developmental telomere attrition--a measure of cellular aging associated with increased morbidity and reduced life-expectancy that we argue could be used as a measure of somatic state--showed shorter latencies to probe ambiguous stimuli. This would usually be interpreted as evidence for a more positive or 'optimistic' affective state. Thus, increased competition in the nest and poor current somatic state appear to have opposite effects on cognitive biases. Our results lead us to question whether increased expectation of reward when presented with ambiguous stimuli always indicates a more positive affective state. We discuss the possibility that birds in poor current somatic state may adopt a 'hungry' cognitive phenotype that could drive behaviour commonly interpreted as 'optimism' in food-rewarded cognitive bias tasks.

No MeSH data available.


Effects of developmental competition on judgment bias.(A) Latency to probe as a function of stimulus valence for birds in the two brood-size treatments. Data are mean ± 1 s.e. latency to probe in the cognitive bias test trials. (B) The same data shown in panel A standardised so that the latencies to probe POS and NEG are 0 and 1 respectively. This standardisation removes differences in speed to probe POS and NEG between treatments, and hence reveals the differences in the shapes of the generalisation gradients between treatments. Note that this standardisation is for visualisation purposes only and was not used in the data analysis (see text for details). (C) Latency to probe as a function of stimulus valence for birds at the top of the weight hierarchy in the nest (0 or 1 heavier competitors) and birds at the bottom of the weight hierarchy (2–6 heavier competitors). Data are mean ± 1 se latency to probe in the cognitive bias test trials. The dichotomization of the data into the groups 0–1 and 2–6, is for visualisation purposes only; all statistical analyses were conducted using the number of heavier competitors as a continuous predictor variable. (D) The same data shown in panel C standardised so that the latencies to probe POS and NEG are 0 and 1 respectively. Note that the standard errors shown on all of the plots in this figure give a false impression (underestimate) of the significant differences between the groups due to the fact that birds from the same genetic family are present in both treatment groups.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4519284&req=5

pone.0132602.g001: Effects of developmental competition on judgment bias.(A) Latency to probe as a function of stimulus valence for birds in the two brood-size treatments. Data are mean ± 1 s.e. latency to probe in the cognitive bias test trials. (B) The same data shown in panel A standardised so that the latencies to probe POS and NEG are 0 and 1 respectively. This standardisation removes differences in speed to probe POS and NEG between treatments, and hence reveals the differences in the shapes of the generalisation gradients between treatments. Note that this standardisation is for visualisation purposes only and was not used in the data analysis (see text for details). (C) Latency to probe as a function of stimulus valence for birds at the top of the weight hierarchy in the nest (0 or 1 heavier competitors) and birds at the bottom of the weight hierarchy (2–6 heavier competitors). Data are mean ± 1 se latency to probe in the cognitive bias test trials. The dichotomization of the data into the groups 0–1 and 2–6, is for visualisation purposes only; all statistical analyses were conducted using the number of heavier competitors as a continuous predictor variable. (D) The same data shown in panel C standardised so that the latencies to probe POS and NEG are 0 and 1 respectively. Note that the standard errors shown on all of the plots in this figure give a false impression (underestimate) of the significant differences between the groups due to the fact that birds from the same genetic family are present in both treatment groups.

Mentions: Fig 1A shows that birds from the high-competition treatment were faster to probe all but the Near POS stimulus. Our first step was to explore whether there was an effect of treatment on latency to probe just the trained stimuli (POS and NEG). We fitted a model with latency to probe POS and NEG stimuli (logged) as the dependent variable and stimulus valence (1 or 5), brood size treatment and their interaction as fixed predictors. Valence significantly predicted latency to probe, with birds probing POS stimuli faster (GLMM: B for POS±s.e. = -2.07±0.07, X2(1) = 1003.91, p < 0.001). Brood-size treatment had a significant main effect on latency to probe, with birds from high-competition nests probing faster (GLMM: B for high-competition nests±s.e. = -0.68±0.26, X2(1) = 3.97, p = 0.046). There was a significant interaction between valence and treatment reflecting a greater effect of treatment on the latency to probe NEG stimuli (GLMM: B±s.e. = 0.29±0.10, X2(1) = 8.45, p = 0.004). Since this analysis shows an effect of treatment on the latency of the birds to probe the trained stimuli, we calculated the mean probe latency to the POS and NEG stimuli for each bird (henceforth its ‘speed’), and used this as a covariate in the following analysis of latencies to probe the ambiguous stimuli (Near POS, MID and Near NEG).


Opposite Effects of Early-Life Competition and Developmental Telomere Attrition on Cognitive Biases in Juvenile European Starlings.

Bateson M, Emmerson M, Ergün G, Monaghan P, Nettle D - PLoS ONE (2015)

Effects of developmental competition on judgment bias.(A) Latency to probe as a function of stimulus valence for birds in the two brood-size treatments. Data are mean ± 1 s.e. latency to probe in the cognitive bias test trials. (B) The same data shown in panel A standardised so that the latencies to probe POS and NEG are 0 and 1 respectively. This standardisation removes differences in speed to probe POS and NEG between treatments, and hence reveals the differences in the shapes of the generalisation gradients between treatments. Note that this standardisation is for visualisation purposes only and was not used in the data analysis (see text for details). (C) Latency to probe as a function of stimulus valence for birds at the top of the weight hierarchy in the nest (0 or 1 heavier competitors) and birds at the bottom of the weight hierarchy (2–6 heavier competitors). Data are mean ± 1 se latency to probe in the cognitive bias test trials. The dichotomization of the data into the groups 0–1 and 2–6, is for visualisation purposes only; all statistical analyses were conducted using the number of heavier competitors as a continuous predictor variable. (D) The same data shown in panel C standardised so that the latencies to probe POS and NEG are 0 and 1 respectively. Note that the standard errors shown on all of the plots in this figure give a false impression (underestimate) of the significant differences between the groups due to the fact that birds from the same genetic family are present in both treatment groups.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4519284&req=5

pone.0132602.g001: Effects of developmental competition on judgment bias.(A) Latency to probe as a function of stimulus valence for birds in the two brood-size treatments. Data are mean ± 1 s.e. latency to probe in the cognitive bias test trials. (B) The same data shown in panel A standardised so that the latencies to probe POS and NEG are 0 and 1 respectively. This standardisation removes differences in speed to probe POS and NEG between treatments, and hence reveals the differences in the shapes of the generalisation gradients between treatments. Note that this standardisation is for visualisation purposes only and was not used in the data analysis (see text for details). (C) Latency to probe as a function of stimulus valence for birds at the top of the weight hierarchy in the nest (0 or 1 heavier competitors) and birds at the bottom of the weight hierarchy (2–6 heavier competitors). Data are mean ± 1 se latency to probe in the cognitive bias test trials. The dichotomization of the data into the groups 0–1 and 2–6, is for visualisation purposes only; all statistical analyses were conducted using the number of heavier competitors as a continuous predictor variable. (D) The same data shown in panel C standardised so that the latencies to probe POS and NEG are 0 and 1 respectively. Note that the standard errors shown on all of the plots in this figure give a false impression (underestimate) of the significant differences between the groups due to the fact that birds from the same genetic family are present in both treatment groups.
Mentions: Fig 1A shows that birds from the high-competition treatment were faster to probe all but the Near POS stimulus. Our first step was to explore whether there was an effect of treatment on latency to probe just the trained stimuli (POS and NEG). We fitted a model with latency to probe POS and NEG stimuli (logged) as the dependent variable and stimulus valence (1 or 5), brood size treatment and their interaction as fixed predictors. Valence significantly predicted latency to probe, with birds probing POS stimuli faster (GLMM: B for POS±s.e. = -2.07±0.07, X2(1) = 1003.91, p < 0.001). Brood-size treatment had a significant main effect on latency to probe, with birds from high-competition nests probing faster (GLMM: B for high-competition nests±s.e. = -0.68±0.26, X2(1) = 3.97, p = 0.046). There was a significant interaction between valence and treatment reflecting a greater effect of treatment on the latency to probe NEG stimuli (GLMM: B±s.e. = 0.29±0.10, X2(1) = 8.45, p = 0.004). Since this analysis shows an effect of treatment on the latency of the birds to probe the trained stimuli, we calculated the mean probe latency to the POS and NEG stimuli for each bird (henceforth its ‘speed’), and used this as a covariate in the following analysis of latencies to probe the ambiguous stimuli (Near POS, MID and Near NEG).

Bottom Line: We predicted that starlings from larger broods, specifically those that had experienced more nest competitors larger than themselves would exhibit reduced expectation of reward, indicative of a 'pessimistic', depression-like mood.Thus, increased competition in the nest and poor current somatic state appear to have opposite effects on cognitive biases.Our results lead us to question whether increased expectation of reward when presented with ambiguous stimuli always indicates a more positive affective state.

View Article: PubMed Central - PubMed

Affiliation: Centre for Behaviour & Evolution and Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom.

ABSTRACT
Moods are enduring affective states that we hypothesise should be affected by an individual's developmental experience and its current somatic state. We tested whether early-life adversity, induced by manipulating brood size, subsequently altered juvenile European starlings' (Sturnus vulgaris) decisions in a judgment bias task designed to provide a cognitive measure of mood. We predicted that starlings from larger broods, specifically those that had experienced more nest competitors larger than themselves would exhibit reduced expectation of reward, indicative of a 'pessimistic', depression-like mood. We used a go/no-go task, in which 30 starlings were trained to probe a grey card disc associated with a palatable mealworm hidden underneath and avoid a different shade of grey card disc associated with a noxious quinine-injected mealworm hidden underneath. Birds' response latencies to the trained stimuli and also to novel, ambiguous stimuli intermediate between these were subsequently tested. Birds that had experienced greater competition in the nest were faster to probe trained stimuli, and it was therefore necessary to control statistically for this difference in subsequent analyses of the birds' responses to the ambiguous stimuli. As predicted, birds with more, larger nest competitors showed relatively longer latencies to probe ambiguous stimuli, suggesting reduced expectation of reward and a 'pessimistic', depression-like mood. However, birds with greater developmental telomere attrition--a measure of cellular aging associated with increased morbidity and reduced life-expectancy that we argue could be used as a measure of somatic state--showed shorter latencies to probe ambiguous stimuli. This would usually be interpreted as evidence for a more positive or 'optimistic' affective state. Thus, increased competition in the nest and poor current somatic state appear to have opposite effects on cognitive biases. Our results lead us to question whether increased expectation of reward when presented with ambiguous stimuli always indicates a more positive affective state. We discuss the possibility that birds in poor current somatic state may adopt a 'hungry' cognitive phenotype that could drive behaviour commonly interpreted as 'optimism' in food-rewarded cognitive bias tasks.

No MeSH data available.