Changes

==Visual Communication==

==Visual Communication==

The function of the visual system of cats is highly biased in favour of [[Feline Predatory Behaviour|predatory behaviour]]. The cat’s [[Eye - Anatomy & Physiology#The Wall (retina, uvea and sclera)|retina]] has three times the rod density of the human eye, contributing to the light detection threshold in cats being eight times lower than in man. Although their vision is not monochromatic, cats have sixteen times fewer wavelength comparing retinal ganglia than primates and are '''behaviourally colour blind'''. The cat’s enhanced visual sensitivity to brightness, patterns and movement block learning associated with differences in colour; under normal conditions cats do not appear to learn associations based on colour discrimination. The [[Cranial Nerves - Anatomy & Physiology#Optic Nerve (II)|optic nerve]] in the cat has a much lower density of nerve fibres than in man, due to the much smaller amount of information transmitted from the cat’s retina. This is because the ratio of ganglionic cells to photoreceptors is very high in the cat; there is a far higher level of integration of information at the level of the ganglionic layer of the retina. The benefit of this is that '''movement detection is hard-wired into the sensory system''' and able to directly drive fast responding reflexive systems; the cat is therefore much more rapidly attentive and responsive to movement that a human. In a sense, cats “see movement” in the way that we see colour. Overall, its vision has evolved to enable it to see in low light levels, break the camouflage of its prey and quickly detect movement. As a result of the wild cat’s camouflaged coat, [[Timing of Feline Activity|crepuscular and nocturnal activity]] and [[Feline Predatory Behaviour#Hunting Strategies|stealthy use of cover]], visual identification of affiliates is less important than the use of other sensory systems such as [[Feline Communication Behaviour#Olfactory Communication|olfaction]].

The function of the visual system of cats is highly biased in favour of [[Feline Predatory Behaviour|predatory behaviour]]. The cat’s [[Eye - Anatomy & Physiology#The Wall (retina, uvea and sclera)|retina]] has three times the rod density of the human eye, contributing to the light detection threshold in cats being eight times lower than in man. Although their vision is not monochromatic, cats have sixteen times fewer wavelength comparing retinal ganglia than primates and are '''behaviourally colour blind'''. The cat’s enhanced visual sensitivity to brightness, patterns and movement block learning associated with differences in colour; under normal conditions cats do not appear to learn associations based on colour discrimination. The [[Cranial Nerves - Anatomy & Physiology#Optic Nerve (II)|optic nerve]] in the cat has a much lower density of nerve fibres than in man, due to the much smaller amount of information transmitted from the cat’s retina. This is because the ratio of ganglionic cells to photoreceptors is very high in the cat; there is a far higher level of integration of information at the level of the ganglionic layer of the retina. The benefit of this is that '''movement detection is hard-wired into the sensory system''' and able to directly drive fast responding reflexive systems; the cat is therefore much more rapidly attentive and responsive to movement than a human. The overall effect is that cats are attentive to movement in the way that humans are attentive to colour.  

 

The cat's vision has therefore evolved to enable it to see in low light levels, break the camouflage of its prey and quickly detect movement. As a result of the wild cat’s camouflaged coat, [[Timing of Feline Activity|crepuscular and nocturnal activity]] and [[Feline Predatory Behaviour#Hunting Strategies|stealthy use of cover]], visual identification of affiliates is less important than the use of other sensory systems such as [[Feline Communication Behaviour#Olfactory Communication|olfaction]].

Visual communication involves '''facial and body postures''', as well as the '''visual aspects of''' certain behaviour such as '''spray marking''' and '''clawing'''. In general, visual communication is operates over a limited range, in line of sight and is rapidly modified. This gives the signaller a great deal of control over the signal, which can be changed according to the response it elicits. Visual signalling is less effective at night, in adverse weather conditions and dense undergrowth. The main disadvantage of visual communication is that it must be delivered face to face with a competitor, which increases the risk of conflict and injury.  

Visual communication involves '''facial and body postures''', as well as the '''visual aspects of''' certain behaviour such as '''spray marking''' and '''clawing'''. In general, visual communication is operates over a limited range, in line of sight and is rapidly modified. This gives the signaller a great deal of control over the signal, which can be changed according to the response it elicits. Visual signalling is less effective at night, in adverse weather conditions and dense undergrowth. The main disadvantage of visual communication is that it must be delivered face to face with a competitor, which increases the risk of conflict and injury.