Download Answers to Test Your Knowledge questions for

Answers to Test Your Knowledge questions for
Chapter 1 Introduction
Question 1.1
Both drinking and urination are controls that act in the service of the homeostasis (i.e.
maintaining near constancy) of body fluids. As a crucial aspect of homeostasis, both are
strongly influenced by deviations of body water level from its normal value. Dehydration
excites drinking and inhibits the production of urine. Over-hydration inhibits drinking
and promotes the production of urine. As described here, both are examples of negative
feedback, i.e. a deviation from some condition causes action such as to eliminate this
same deviation. Negative feedback is one of the processes that help to maintain
homeostasis but, as you will see later, there are also other processes that serve this same
end.
Question 1.2
Suppose that we wish to test the hypothesis that a drug (X) excites drinking in rats. We
inject animals with the drug and observe that, shortly after the injection, animals tend to
drink. We are led to suppose that X is exerting a causal influence on drinking but we need
to test formally and rigourously this hypothesis. It might be that something to do with the
injection (rather than chemical X) is triggering drinking, e.g. the animals are excited by
the feel of the needle or being handled. Therefore, we need to compare the experimental
treatment (injected with X) with a treatment (control treatment) that is identical to the
experimental treatment in every respect except for the entry of substance X into the body.
Therefore, the control would need to be housed under identical conditions and given an
identical injection of the same size but of a neutral substance. Typically, a salt solution
having the same concentration as the blood is injected. Being like the body's natural
fluids, it is assumed to be a minimal disturbance. The drug versus no drug is termed the
independent variable and the amount drunk by the rats in the two treatments is termed the
dependent variable.
In a within-subjects design the same rats would be injected on different occasions with X
and control substances. In a between-subjects design, 2 different groups of rats would be
used, one the experimental and the other the control group.
Question 1.3
It could be argued that social behaviour emerges from the combination of individuals that
form the group. Social behaviour is not partly present in the behaviour of the individual
when alone. It only emerges when individuals are in a group. Note though that social
behaviour depends upon the properties of the individuals that form the group (e.g. a
person with introvert or extravert tendencies) even though it cannot be reduced to a sum
of such properties.
Question 1.4
No - there need be no conflict here. It is widely assumed that there is a physical
embodiment of mental states such as joy and depression within the nervous system. The
drug would affect the working of the nervous system, which would be felt consciously in
terms of an emotional state.
Question 1.5
This one should really stretch you and maybe irritate you. It is in an area fraught with
complications and dilemmas, so it is impossible to give any really convincing answers or
neat distinctions. However, one might suggest that, when there is a fault in the hardware
of the computer, this is analogous to something being wrong with the structure of the
brain. Tissue abnormalities might be revealed, e.g. by microscopic examination.
Examples would include damage to a particular brain region as in a tumour or bullet
wound. In such cases, the law tends to take the view that there can be diminished
responsibility. If the fault is in the software of the computer, e.g. a programming error,
then by analogy this might suggest that there are no (or less convincing) grounds for
pleading diminished responsibility.
Question 1.6
This would suggest that (1) nervous system structures exert a causal influence on
behaviour but then, as a feedback effect, (2) behaviour exerts some influence on nervous
system structures. (1) is uncontroversial and fairly obvious. (2) is more subtle and
perhaps less obvious. However, as will be discussed in more detail in Chapter 6,
'Development', the behaviour of the whole animal appears to influence the development
of the nervous system For example, by its behaviour the animal sets up social interactions
with other animals (e.g. play) and this affects the individual's development.
Question 1.7
Rats are a species that use their paws to manipulate features of the environment in order
to gain access to food etc.. Pressing the lever in a Skinner box is a manipulation of the
environment not too far removed from this. In their evolution, pigeons have pecked to
obtain food and key pecking in the Skinner box has similarities with this. In these
regards, the Skinner box might be said to 'make sense'. However, others would argue that
the limitations of space and artificiality of the task make the Skinner box a poor model of
anything encountered in a species' natural history.
Question 1.8
One possible analogy is that the hardware of the computer, e.g. the circuits of electronic
components, are analogous to the physical structure of the brain, e.g. its neurons and the
synapses between them. In such terms, the software of the computer (the programme that
is run on it) is analogous to the mind. Such an analogy is, of course, not perfect and one
can criticize it but this is true of any analogy. Such issues are explored further in Chapter
22, 'Brains, minds and consciousness'.