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- Aronsson, Marianne, 1978-, et al.
(author)
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Colour and pattern similarity in mimicry : evidence for a hierarchical discriminative learning of different components
- 2012
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In: Animal Behaviour. - : Elsevier BV. - 0003-3472 .- 1095-8282. ; 84:4, s. 881-887
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Journal article (peer-reviewed)abstract
- Many aposematic species combine their bright colours with a black pattern that produces internal contrasts. Studies have shown that birds often pay attention to some parts of a signalling pattern and disregard others, which could be of importance in Batesian mimicry, where a palatable species copies the visual appearance of a distasteful model in order to deceive predators. We used domestic chicks, Gallus gallus domesticus, and artificial prey signals to investigate whether predators use different warning colour components for discrimination depending on the degree of information about prey quality they convey. This study supports earlier findings of the importance of colour for discrimination among prey but also provides evidence that other less associable signal properties such as internal patterning, when holding valuable discriminatory information, can be used to assess prey quality in a hierarchical manner. The results also suggest that, in certain circumstances, the presence of a palatable mimic can have positive effects on learning, resulting in 'super-Mullerian' effects. We propose that the degree of selection for perfect mimicry may be dependent on the proportion of well-educated predators in the population.
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| 2. |
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| 3. |
- Aronsson, Marianne, 1978-
(author)
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Colour patterns in warning displays
- 2012
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Doctoral thesis (other academic/artistic)abstract
- In aposematism a prey species use bright colours, often combined with a black contrasting pattern, to signal unprofitability as prey to potential predators. Although there are several different hypotheses about the presence of these internally contrasting patterns, there is little experimental evidence of any beneficial effects. In this thesis I have used bird predators and artificial prey signals to investigate if the contrasting internal patterns in warning displays may have evolved to increase signal efficacy, especially regarding the speed of avoidance learning. In paper I the relative importance of colour and pattern in avoidance learning was studied. The conclusion was that birds primarily attend to colour, not pattern, when learning the discrimination, which was further supported by the results in paper II-IV, all suggesting a secondary role of patterns. In paper II I show that predators may to some degree use patterns for discrimination, if they convey important information about prey quality. The predators showed a hierarchical way of learning warning colour components, where colour is learned to a higher degree than pattern. In paper III I investigate if internal contrasting patterns promote avoidance learning by increasing conspicuousness as prey-to-background contrast does. The study did not support this idea, as the presence of internal black patterns did not improve avoidance learning on a colour matching background. In paper IV, however, I show that the presence of many internal colour boundaries resulted in faster avoidance learning on a multi-coloured background, and predator generalization favoured more internal boundaries, while there was no effect of pattern regularity. From these studies I conclude that internal pattern contrasts may function to increase the efficacy of the warning colour, its salience, and as a means for aposematic prey to be discriminated from harmful mimics. However, the major finding is the importance of colour over pattern.
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| 4. |
- Aronsson, Marianne, et al.
(author)
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Domestic chicks primarily attend to colour, not pattern, when learning an aposematic coloration
- 2008
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In: Animal Behaviour. - : Elsevier BV. - 0003-3472 .- 1095-8282. ; 75, s. 417-423
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Journal article (peer-reviewed)abstract
- Aposematic conspicuous coloration consists of one or a few bright colours, often in combination with a black defined internal pattern. The function of conspicuousness in aposematism has been ascribed to signal efficacy, based on experimental evidence involving prey items with uniform colour that contrast with the background. Although there are several hypotheses about the existence of internal contrasts within warning coloration, little experimental evidence has been presented. Here we used domestic chicks, Gallus gallus domesticus, to investigate the relative importance of colour and pattern in avoidance learning. Birds in two groups were first trained to discriminate between a grey positive stimulus and a cyan negative stimulus with either black dots or stripes. Pieces of mealworms, untreated and palatable or made unpalatable by soaking in quinine were used as reinforcers. Secondly, to determine what birds had attended to when learning the discrimination, colour and/or pattern, we compared how they generalized their avoidance of the ‘training stimulus’ to either a ‘colour only’ or ‘pattern only’ stimulus. The chicks learned to avoid the unpalatable prey items but showed no difference in behaviour depending on the type of pattern presented. The generalization test showed that birds avoided the novel ‘colour only’ stimulus at least as much as the ‘training stimulus’, and did not generalize their avoidance to the ‘pattern only’ stimulus. We conclude that birds do not necessarily attend to complex patterns when learning a warning signal, and domestic chicks primarily learn a bright colour rather than an equally novel conspicuous black pattern.
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| 5. |
- Aronsson, Marianne, et al.
(author)
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Evidence of signaling benefits to contrasting internal color boundaries in warning coloration
- 2013
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In: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 24:2, s. 349-354
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Journal article (peer-reviewed)abstract
- It has been suggested that the common existence of regular patterning in aposematic prey animals makes them stand out from the background, improving detection and recognition. Another suggestion is that internal patterns could have a similar positive effect on predator aversion learning as prey-to-background contrast. We used wild caught blue tits (Cyanistes caeruleus) and artificial prey signals to investigate if internal color boundaries, pattern regularity and pattern symmetry affect learning. Birds in different treatments were trained, on a complex background, to discriminate between artificial prey with different nonrewarding color stimuli with a black pattern and rewarding stimuli without a black pattern, followed by a generalization test. This study provides evidence of learning benefits to internally contrasting patterns as the striped prey stimuli were learned faster than the unstriped. Also, we found no beneficial effects of pattern regularity and symmetry. The birds generalized more between prey with different black patterns than to the profitable prey, suggesting that color is of foremost importance. The generalization test also showed a greater avoidance of striped than that of unstriped prey, suggesting some attention on patterns. Thus, internal patterning may affect signal salience and in some circumstances benefit prey due to both a faster avoidance learning and generalization behavior.
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| 6. |
- Aronsson, Marianne, et al.
(author)
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Importance of internal pattern contrast and contrast against the background in aposematic signals.
- 2009
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In: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 20:6, s. 1356-1362
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Journal article (peer-reviewed)abstract
- Aposematic color patterns that signal prey unprofitability are suggested to work best when there is high contrast within the animal color pattern or between the animal and its background. Studies show that prey contrast against the background increases the signal efficiency. This has occasionally been extended to also explain the presence of internal patterns. We used domestic chicks, Gallus gallus domesticus, to investigate the relative importance for avoidance learning of within-prey pattern contrast and prey contrast against the background. In a series of trials, birds were first trained to avoid artificially made aposematic mealworms that were plain red or red with black stripes, and to discriminate them from palatable brown mealworms, on either a red or a brown background. Second, we investigated how the birds generalized between striped and nonstriped prey. The chicks showed faster avoidance learning when the basic color of the aposematic prey (red) contrasted with the background color (brown). However, there was no similar effect of internal pattern contrast. The generalization test showed a complete generalization between the nonstriped and the striped prey. We conclude that contrasting internal patterns do not necessarily affect predator avoidance learning the same way as shown for prey-to-background contrast in aposematic prey.
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| 9. |
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Barn i tid och rum
- 1984
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Editorial collection (other academic/artistic)abstract
- En antologi med 10 artiklar av författare från olika discipliner. Utifrån teoretiker som Ariès, Bourdieu, Berger och Luckmann, Freud, Mead, Piaget m.fl. belyser författarna barns villkor förr och nu och där arbete och fritid flyter samman.
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| 10. |
- Brooks, Samantha J, et al.
(author)
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Obsessive-compulsivity and working memory are associated with differential prefrontal cortex and insula activation in adolescents with a recent diagnosis of an eating disorder
- 2014
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In: Psychiatry Research. - : Elsevier BV. - 0165-1781 .- 1872-7123 .- 0925-4927. ; 224:3, s. 246-253
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Journal article (peer-reviewed)abstract
- The role of rumination at the beginning of eating disorder (ED) is not well understood. We hypothesised that impulsivity, rumination and restriction could be associated with neural activity in response to food stimuli in young individuals with eating disorders (ED). We measured neural responses with functional magnetic resonance imaging (fMRI), tested working memory (WM) and administered the eating disorders examination questionnaire (EDE-Q), Barratt impulsivity scale (BIS-11) and obsessive-compulsive inventory (OCI-R) in 15 adolescent females with eating disorder not otherwise specified (EDNOS) (mean age 15 years) and 20 age-matched healthy control females. We found that EDNOS subjects had significantly higher scores on the BIS 11, EDE-Q and OCI-R scales. Significantly increased neural responses to food images in the EDNOS group were observed in the prefrontal circuitry. OCI-R scores in the EDNOS group also significantly correlated with activity in the prefrontal circuitry and the cerebellum. Significantly slower WM responses negatively correlated with bilateral superior frontal gyrus activity in the EDNOS group. We conclude that ruminations, linked to WM, are present in adolescent females newly diagnosed with EDNOS. These may be risk factors for the development of an eating disorder and may be detectable before disease onset.
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