Colour categorization
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The presented study examines the question of colour categorization in relation to the hypothesis of linguistic relativity. The study is based on research conducted by Gilbert et al. (2006) and their claim that linguistic colour categorization in a particular language helps colour recognition and speeds the process of colour discrimination for colours from different linguistic categories but only for the right visual field. Our study approached the research question differently. We used the same methodology as Gilbert's team et al. (2006), but we used different colour categories in the Czech language and significantly enlarged the number of participants to 106 undergraduate psychology students. Our results show that the fastest reaction times were in trials when the target was located in the left visual field, quite opposite from the Gilbert's et al. (2006) study. We argue that this finding is based on different processes than simple colour linguistic categorisation and attentional processes actually play an important role in the task.
- Klíčová slova
- Colour categorization, Language, The hypothesis of linguistic relativity,
- MeSH
- barva MeSH
- jazyk (prostředek komunikace) * MeSH
- lidé MeSH
- lingvistika MeSH
- pozornost MeSH
- vnímání barev * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Despite object categorization being an important ability for the survival of wild animals, the principles behind this ability have been only scarcely studied using wild-ranging, untrained animals. Reiterating our previous study undertaken with wild-ranging titmice on winter feeders (Nováková et al. Behav Process 143:7-12, 2017), we aimed to test two hypotheses of object recognition proposed by animal psychology studies: the particulate feature theory and recognition by components in the methodological paradigm of nest defence. We tested whether the parents of the red-backed shrike (Lanius collurio) recognize the dummies of the common kestrel (Falco tinnunculus), which is a potential predator of large chicks or fledglings, as a threat in case when their body parts are scrambled. The kestrel dummy was presented with the head at the top, in the middle, and at the bottom of the body. We showed that the shrikes did not consider dummies of a kestrel with an inappropriately placed head as a threat to the nest and attacked it equally scarcely as the harmless control. These results support the theory of recognition by components, presuming that the mutual position of body parts is essential for appropriate recognition of the object. When the body parts were scrambled, most of shrikes were not able to identify the kestrel in such an object despite all local features (eye, beak, colouration, and claws) being present. Nevertheless, shrikes did not consider the scrambled dummies as completely harmless, because they fed their chicks in their presence significantly less often than in the presence of harmless control.
- Klíčová slova
- Categorization, Global and local features, Kestrel, Nest defence, Recognition, Red-backed shrike,
- MeSH
- divoká zvířata MeSH
- Falconiformes * MeSH
- Passeriformes * MeSH
- roční období MeSH
- rozpoznávání (psychologie) MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Birds are strongly motivated to recognize various predators to secure survival and reproductive success. Thus, predator recognition provides a useful tool for the investigation of the process of discrimination and categorization in non-trained animals. The most important role in this process is usually attributed to the prominent unique features shared by all members within the wider category of predators (sharp teeth or beaks, claws, talons and conspicuous eyes). However, birds are also able to discriminate between particular predator species according to their species-specific features (based mainly on colouration). We manipulated general raptor salient features (hooked beak, talons with claws and eyes with supraorbital ridges) and/or species-specific plumage colouration on the dummy of a Eurasian kestrel (Falco tinnunculus) to investigate their importance in the recognition process of the red-backed shrikes (Lanius collurio) during nest defence. We showed that the presence of general raptor salient features is necessary for the recognition of a predator. The kestrel dummy with natural species-specific colouration with altered raptor salient features was treated by shrikes as a harmless bird. Nevertheless, pronounced changes in colouration also prevented successful recognition of the dummy as a kestrel, even when raptor salient features of a raptor were present.
- Klíčová slova
- Categorization, Colouration, Discrimination, Nest defence, Salient features,
- MeSH
- dravci * MeSH
- Falconiformes * MeSH
- Passeriformes * MeSH
- rozpoznávání (psychologie) MeSH
- zobák MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Previous studies have demonstrated that humans have a remarkable capacity to memorise a large number of scenes. The research on memorability has shown that memory performance can be predicted by the content of an image. We explored how remembering an image is affected by the image properties within the context of the reference set, including the extent to which it is different from its neighbours (image-space sparseness) and if it belongs to the same category as its neighbours (uniformity). We used a reference set of 2,048 scenes (64 categories), evaluated pairwise scene similarity using deep features from a pretrained convolutional neural network (CNN), and calculated the image-space sparseness and uniformity for each image. We ran three memory experiments, varying the memory workload with experiment length and colour/greyscale presentation. We measured the sensitivity and criterion value changes as a function of image-space sparseness and uniformity. Across all three experiments, we found separate effects of 1) sparseness on memory sensitivity, and 2) uniformity on the recognition criterion. People better remembered (and correctly rejected) images that were more separated from others. People tended to make more false alarms and fewer miss errors in images from categorically uniform portions of the image-space. We propose that both image-space properties affect human decisions when recognising images. Additionally, we found that colour presentation did not yield better memory performance over grayscale images.
- Klíčová slova
- Categorization, Memory: visual working and short-term memory, Scene perception,
- MeSH
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- neuronové sítě * MeSH
- paměť fyziologie MeSH
- rozpomínání fyziologie MeSH
- rozpoznávání (psychologie) fyziologie MeSH
- rozpoznávání obrazu fyziologie MeSH
- světelná stimulace metody MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
It is supposed that body size serves as an important cue in the recognition of relevant stimuli in nature. As predators of varying body size pose differing levels of threat, their potential prey should be able to discriminate between them. We tested the reaction of great tits (Parus major) to the dummies of their common predator (the European sparrowhawk-Accipiter nisus) in natural and reduced body sizes under laboratory conditions. All of the tested dummies possessed local raptor-specific features (hooked beak, claws with talons, and conspicuous eyes), but differed in global species-specific features: body size (large - the size of a sparrowhawk, small - the size of a great tit) and colouration (sparrowhawk, great tit, robin, and pigeon). The sparrowhawk-coloured dummies evoked fear regardless of their size while both great tit- and pigeon-coloured dummies evoked no fear reaction. The body size was used as the cue only for the discrimination of the robin-coloured dummies. The differences in reactions to the dummies with robin colouration (species unimportant to the great tits) could be explained as that the tits are able to recognize these birds in nature, but not so undoubtedly as the predator or the conspecific.
- Klíčová slova
- Body size, Categorization, Colouration, Predator, Recognition, Untrained birds,
- MeSH
- chování zvířat fyziologie MeSH
- Passeriformes fyziologie MeSH
- predátorské chování fyziologie MeSH
- rozpoznávání obrazu fyziologie MeSH
- velikost těla fyziologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
We compared the responses of the nesting red-backed shrikes (Lanius collurio) to three dummies of a common nest predator, the Eurasian jay (Garrulus glandarius), each made from a different material (stuffed, plush, and silicone). The shrikes performed defensive behaviour including attacks on all three dummies. Nevertheless, the number of attacks significantly decreased from the stuffed dummy through the plush dummy and finally to the silicone dummy. Our results show that wild birds use not only colours but also other surface features as important cues for recognition and categorization of other bird species. Moreover, the silicone dummy was attacked only when presented after the stuffed or plush dummy. Thus, we concluded that the shrikes recognized the jay only the stuffed (with feathered surface) and plush (with hairy surface) dummies during the first encounter. Recognition of the silicon dummy (with glossy surface) was facilitated by previous encounters with the more accurate model. This process resembles the effect of perceptual priming, which is widely described in the literature on humans.
BACKGROUND: In contrast to traditional models of purifying selection and a single aposematic signal in Müllerian complexes, some communities of unprofitable prey contain members with multiple aposematic patterns. Processes responsible for diversity in aposematic signaling are poorly understood and large multi-species communities are seldom considered. RESULTS: We analyzed the phylogeny and aposematic patterns of closely related Eniclases net-winged beetles in New Guinea using mtDNA and nextRAD data. We suggest three clades of closely related and incompletely reproductively isolated lineages, detail the extent of polymorphism among Eniclases, and categorize their low-contrast aposematic patterns. The warning signal of Eniclases consists of body shape and color, with ambiguous color perception under some circumstances, i.e., when resting on the undersides of leaves. Field observations suggest that perception of the aposematic signal is affected by beetle behavior and environmental conditions. Local communities containing Eniclases consisted of 7-85 metriorrhynchine species assigned to 3-10 colour patterns. CONCLUSION: As a result, we suggest that under certain light conditions the aposematic colour signal is less apparent than the body shape in net-winged beetle communities. We document variable environmental factors in our study area and highly diverse multi-species communities of other net-winged beetles. Which implies dynamically changing community structure in space and time. Variable environmental conditions and diverse community composition are suggested to be favorable for the persistence of multiple aposematic patterns, imperfect mimics, and intraspecific polymorphism. Further research should identify the relative effect of these factors on purifying selection and the alleles which are responsible for phenotypic differences.
- Klíčová slova
- Lycidae, Müllerian mimicry, New Guinea, NextRAD, Phylogeny, mtDNA,
- Publikační typ
- časopisecké články MeSH
