The device was tested and validated in three fMRI experiments involving basic visual perception, a simple colour discrimination task, and a blocked multisensory visuo-tactile task.
We gave two groups of starlings a sequential colour discrimination task, where one colour signalled palatable mealworms and the other signalled mealworms that had been either injected with or coated with quinine solution (designed to simulate prey that stored and secreted their chemical defences, respectively).
These results suggest that the previously observed impairment on the first of a pair of object discrimination tasks after aceperone is a consequence of disruption of a mechanism common to both shape and colour discrimination learning.
Ideally, colour discrimination would require a large number of receptors specifically sensitive to small bands of the spectrum, but the number would have to be extremely large because the capacity for hue discrimination is extremely great, as has been indicated.
The reduction of overlap between adjacent spectral channels due to the coloured filters is beneficial for colour discrimination, because it increases the volume of object-colour solid [ 24, 25] (Fig. 3).
Further consideration of the learning impairment after aceperone in the marmoset: effects of the drug on shape and colour discrimination and on an alternation task.
At the same time compared to other potential tit predators (mammals or reptiles) birds have a highly sophisticated visual system with good colour discrimination abilities [ 36, 60, 61] and thus are expected to exert strong selection pressures on the visual appearance of their prey.
Colour discrimination was usually described as a fast form of learning [27], compared, for instance, with learning of visual patterns, which usually takes longer (twenty or more trials).
Image segmentation was performed by RGB colour discrimination using threshold ranges such that a binary overlay was created covering only the positively stained areas.
