Polysemy and metaphor in perception verbs: a cross-linguistic study

5.1.1. PHYSIOLOGY OF THE SENSES 
A complete understanding of how human perception works must include 
descriptions of the three elements (PR, OP, P) mentioned above. It is necessary to 
understand which parts of our body and brain are involved in the perceptual process, and 
how these organs work. The reason for this is that the function and limitations of these 
systems shape and constrain our perceptual processes, the way in which we experience 
the world. As we have said before, our experience and understanding of the world 
motivates our conceptual categories, the meaning of words. Therefore, as we shall see in 
Chapter 6, our perceptual system must also constrain and affect the way we 
questioned throughout Western history by various philosophers (see Vinge 1975) and, more recently, by 
sensory scientists (see Wolfe 1988:xi-xii). 

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conceptualise and use our sense-related language. This is also constrained by the way we 
– as human beings – perceive perception, that is to say how we think and how we 
experience the act of perception itself.
A full detailed description of human perceptual systems lies outside the scope of 
this thesis
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. In the following subsections, however, I will include a brief description of 
the physiology of each sense, together with a brief discussion of our ‘perception of 
perception’. These will be extended in Section 5.2, when the properties defining these 
senses are introduced. As shown in the analysis, these two constraints – sense 
physiology and our perception – do not always coincide. The way we think we perceive 
with these senses sometimes does not correspond to the way in which the physiological 
processes take place.
5.1.1.1. Vision 
The eyes are the first element in the visual system. Eyes capture light – stimulus 
for vision – and generate messages about it. The human eye consists of three concentric 
layers: the fibrous tunic (outermost layer), the vascular tunic (middle layer), and the 
retina. The function of the outermost layer, the fibrous tunic, is to protect the eyeball. It 
consists of the sclera (white part) and the cornea (transparent). The function of the 
middle layer is to nourish the eyeball. It consists of the choroid, a dark pigment that 
nourishes the retina, and the ciliary body, the structure that contains the aqueous humor 
that fills the anterior chamber. The ciliary body gives rise to the iris, a circular patch of 
tissue that gives the eye its characteristic colour. In the middle of the iris lies the pupil, 
an opening within two sets of muscles. These muscles allow the change of the size of the 
pupil, which in turn controls the amount of light reaching the back of the eye. Behind the 
iris, there is an optical element of the eye, the crystalline lens. The lens must be 
transparent to provide a good vision; an opacity or reduced transparency of the lens – 
known as cataracts – would cause a deficient visual perception or even blindness.
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See Howes (1991) for a collection of papers devoted to the anthropology of the senses in 
different cultures. Ackerman (1990) is also an exploration of the origin and evolution of the senses, as 
well as their variation across cultures.
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For a full description of the perceptual systems and processes, see Gibson (1966), Harper 
(1972), Held (1988), Maelicke (1990), Sekuler and Blake (1994), Wolfe (1988), among others. 

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The lens is composed of three components: the elastic capsule, the epithelial 
layers and the lens itself. The main function of the capsule is to mould the shape of the 
lens, thus focusing sharply near or distant objects upon the retina. This process is called 
‘accommodation’ (Harper 1972: 115; Sekuler and Blake 1993: 38). Finally, between the 
lens and the next layer, the retina, there is the vitreous chamber. 
The retina is the neural tissue at the back of the eye. Some landmarks can be 
identified in the retina: the macula, in whose centre lies the fovea, the part stimulated by 
an object in the direct line of sight; the optic disks, where nerve fibres exit the retina 
carrying information to the brain; and the pigment epithelium. 
As we have said before, the physical stimulus for vision is light. The visual 
system can respond to a very large range of stimulus intensities. Light brings 
information about the objects in the environment (Gibson 1966). However, in order for 
light to provide information, there are some requirements to be fulfilled (Sekuler and 
Blake 1994: 44):
(i) Light must be sufficiently intense to penetrate the eyes, reaching the photosensitive material in the 
retina. 
(ii) The distribution of light must be properly focused. 
(iii) The pattern of light falling on the retina must preserve the spatial structure of the object from 
which it is reflected; otherwise, it will not be useful as a source of information about the structure and 
layout of objects. 
The incoming light must pass through a complex of neural elements before 
reaching the photoreceptors in the macula, which are actually responsible for converting 
light into neural signals. There are two types of photoreceptors: cones, which work in 
daylight; and rods, which work in dim illumination. These photoreceptors transform the 
so-called retinal image – the pattern of light distribution reaching the retina – into a 
neural image. This neural image passes onto a network of diverse cells called collector 
cells. These cells integrate all the information from groups of neighbouring 
photoreceptors. The output from the network of collector cells provides the input to the 
retinal ganglion cells. Due to the centre / surround organisation of their receptive fields, 
their main task is to detect differences in light level or contrast. These differences, as 
discussed below, are reflected in language. 
The axons of the ganglion cells form the optic nerve that provides all the input 
data for the neural processing of visual information within the brain. The optic nerves 

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from both eyes converge at the optic chiasm. The optic nerve from each eye branches 
into two segments – one crossed, where fibres cross to the opposite side of the brain; the 
other uncrossed, where fibres do not change sides. Within the chiasm, crossed fibres 
from one eye join with uncrossed fibres from the other eye. These new combinations are 
called optic tracts. Most of these fibres are projected to a cluster of cell bodies called the 
lateral geniculate nucleus (LGN); and the remaining to areas of the midbrain, such as the 
superior colliculus. This is designed to guide orienting movements of the eyes and head 
towards detected objects. This ability to orientate the eyes towards the object is reflected 
in the language in expressions such as point of view and will be represented later in the 
analysis under the property . The colliculus is also prepared for detecting 
objects located away from the point of fixation (Sparks 1988). That is why vision, 
together with hearing, are called the far distance senses: There is no need for the object 
perceived to be close to the eye
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. The LGN has two distinct populations of neurones – 
magnocellular and parvocellular cells. The output from these cells is sent to the visual 
cortex in the occipital lobe, the major visual centre. The visual cortex is composed of 
cortical cells that respond to stimulation of a restricted area of the retina. These cells 
register information about orientation, direction of motion, binocularity and colour.
In sum, vision provides us with information about the shape, size, orientation, 
colour, distance and motion of the OP. In Western society, vision is considered as the 
most reliable sense, as the sense that offers the most accurate information about the 
world outside. 
It is important to notice how the physiology of perception and our perception of 
perception is sometimes different. As noticed before, vision is believed to be a distant 
sense. That is to say, we do not need to have contact with what we see. Therefore, 
despite the fact that human beings perceive vision as an external sense the physical 
stimulus for vision – light – must penetrate the eyes to be transformed into neural 
elements. In fact, during the Enlightenment, philosophers saw in this detachment from 
the eyes and the OP the basis for the ‘objectivity’ of vision, and hence, the basis for the 
scientific value of this sense. Properties no
> and no
> in Section 5.2.2 
reflect this fact.
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This is represented by the property no
> in Section 5.2.2. 

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Analogies between the physiology of vision and metaphorical expressions in 
language are very obvious. For instance, the fact that the eyes are the most important 
element in the visual system is reflected in expressions like I couldn’t believe it until I