Contexts and Expectations
Someone once said that there is no meaning without context. Various kinds
of context are important in shaping our interpretation of what we see. As a
reminder of the importance of making clear what is meant by the importance
of 'context' in perception I briefly list here several very different uses
of the term. However, I would not suggest that in practice tidy distinctions
can always be usefully made.
The largest frame is that of the historical context of perception.
Some theorists, such as Marshall McLuhan (1962), Walter Ong (1967) and Donald
Lowe (1982), have argued that there have been shifts over time in
the human 'sensorium' - that is, in the 'balance' of our senses or the
priority which we give to some compared with others. Such argue that
in western urban cultures we have come to rely more on sight than
on any other sense (this was referred to in
Visual Perception 1 as
'ocularcentrism').
Another major framework is that of the socio-cultural context of
perception. Just as there may be subtle differences in human perception
over time there may also be differences attributable to culture. Some
of these were alluded to in
Visual Perception 3. Constance Classen (1993) in her book Worlds of
Sense shows that different cultures accord priority to different
senses - the Ongee of the Andaman Islands, for instance, live in a world
ordered by smell.
A native American Indian writer called Jamake Highwater, who is of
Blackfeet/Cherokee heritage, draws attention in the following extract to
radically different ways of seeing the world:
The drawing by an Indian, on the other hand, records a totally different
scene: Indians gasping in amazement as a floating island, covered with
tall defoliated trees and odd creatures with hairy faces, approaches.
When I showed the two pictures to white people they said in effect: 'Well,
of course you realize that what those Indians thought they saw was not
really there. They were unfamiliar with what was happening to them and so
they misunderstood their experience.' In other words, there were no
defoliated trees, no floating island, but a ship with a party of explorers.
Indians, looking at the same pictures, pause with perplexity, and then
say, 'Well, after all, a ship is a floating island, and what really are
the masts of a ship but the trunks of tall trees?' In other words, what
the Indians saw was real in terms of their own experience.
The Indians saw a floating island while white people saw a ship. Isn't it
also possible - if we use the bounds of twentieth-century imagination -
that another, more alien people with an entirely different way of seeing
and thinking might see neither an island or a ship? They might for example
see the complex networks of molecules that physics tells us produce the
outward shapes, colours and textures that we simply see as objects. Albert
Einstein showed us that objects, as well as scientific observation of them,
are not experienced directly, and that common- sense thinking is a kind
of shorthand that attempts to convert the fluid, sensuous animation and
immediacy of the world into illusory constructs such as stones, trees,
ships and stars.
We see the world in terms of our cultural heritage and the capacity of our
perceptual organs to deliver culturally predetermined messages to us.
(Highwater 1981, 6-8)
Both the historical and socio-cultural context of perception
are vast themes which will not be explored further here,
but such studies do help to emphasize that 'the world' is not simply
indisputably 'out there' but is to some extent constructed in the process
of perception. Within a given socio-cultural context, there are
widely-shared interpretive conventions and practices. Whilst the basic
processes of human perception are largely universal there is scope
for subtle but significant variations over space and time.
Several other kinds of context are commonly referred to. I have referred
already, in
Visual Perception 3,
to the importance of individual factors which can have an influence on
perception. An emphasis on the individual as a context emphasizes the
role of the various long-term characteristics of individual perceivers
such as values, attitudes, habits and so on.
An emphasis on the situational context considers such transitory
situational factors as goals, intentions, situational constraints and
contextual expectancies. Finally, an emphasis on the structural
context stresses structural features and relationships (such as the
relationship between one line and another) 'in' what is perceived -
though the extent to which there is agreement about even such low-level
formal features may vary.
Five main definitions of the scope of the term 'context' have been
listed here in relation to their potential influence on perception:
Whilst it may be useful to be alert to the very different meanings that the
word 'context' can have, disentangling them is problematic.
A very well-known study by Bugelski and Alampay (1961) can be seen as
showing the importance of situational context. Their experiment is often
used as an example of the influence of what psychologists call 'perceptual
set': a predisposition to perceive something in relation to prior perceptual
experiences. Perceptual set is broader than situational context, since it
may involve either long-term (for instance, cultural) prior experience or,
as in this case, short-term or situational factors (Murch 1973, 300-301).
Groups of observers in the experiment were
shown an ambiguous line drawing which was designed to be open to
interpretation either as a rat or as a bald man wearing spectacles.
Prior to seeing this image, two groups were shown from one to four drawings
in a similar style. One group was shown drawings of various animals and
the second group was shown drawings of human faces (see illustration
below). A control group was
shown no pictures beforehand. 81% of the control group reported seeing the
ambiguous image as a man rather than a rat. The more pictures of animals
that the 'animal' group had seen, the more likely they were to see a rat
rather than a man (with 4 prior images of animals 100% then saw a rat).
From 73-80% of the 'faces' group subsequently saw a man rather than a rat.
The influence of perceptual set has also been explored in relation to
the famous image shown below:
This image was designed to be interpreted as either a young woman or an
old woman. It was introduced into the psychological literature by Edwin G Boring
(1930) (though it was published by the British cartoonist W E Hill in 1915,
and is thought to be based on a French version of 15 years earlier). It
is sometimes given the chauvinistic label of 'The Wife and the
Mother-in-Law'. In order to study the role of perceptual set Robert Leeper
(1935) had the image redrawn in two 'biased' forms: one which emphasized the
old woman and the other which emphasized the young woman (see image below).
Leeper varied
the conditions of viewing for five groups. A control group was shown only
the ambiguous drawing, and 65% of this group spontaneously described the
image as that of a young woman. The second and third groups
were first given a verbal description of the old woman and the
young woman respectively. The fourth and fifth groups were first shown the
'old' version and the 'young' version respectively. Groups 2 to 5 were
then shown the original ambiguous image. Leeper found that each of the
primed groups was 'locked-in' to their previous interpretation. 100% of
group 5, which had seen the young version first, interpreted the ambiguous
image as a young woman. 94% of group 4, which had seen the old version
first, reported seeing the old woman in the ambiguous image. The
percentages opting for each interpretation amongst those given verbal
descriptions were much the same as for the control group.
Gerald Murch (1973, 305) was unable to replicate these findings (94% of
his control group first saw the young woman) and suggested that the image
was by then so well-known that this may have influenced the results.
Particular situational contexts set up expectations in the observer.
Bruner and Postman (1949) conducted an
experiment in which playing-cards were used, some of which had the colour
changed from red to black or vice versa. The cards were exposed in
succession for a very short time. Subjects identified them as follows:
Interpretation here was dominated by what the situational context
suggested that people
ought to be seeing. A shorter time of exposure was necessary for
people to name the normal cards than the anomalous ones.
In one experiment, Steven Palmer (1975) first presented a situational
context such as a kitchen scene and then briefly flashed on a
target image. When asked to identify a loaf-like image, people who had first
seen the kitchen correctly identified it as a loaf 80% of the time.
Obviously, a loaf of bread is the kind of thing you’d expect to find in a
kitchen. They were asked to identify an image like an open US mailbox
and an image resembling a drum - two objects not usually associated with
the kitchen. The images were a little ambiguous: the mailbox was a little
like the shape of a loaf with a slice of bread lying next to it, and
the drum could have been interpreted as the lid of a jar. People who had
first seen the kitchen only identified these as a mailbox and a drum 40% of
the time. The ability to identify objects was affected by people’s
expectations concerning what is likely to be found in a kitchen.
I have mentioned that situational contexts generate certain (short-term)
expectations but it is worth noting in passing that expectations may also be
set up by longer-term influences - such as by stereotypes, prejudices and
past experience.
To return to contexts, here is an example of structural context.
This pattern of circles is known as the Ebbinghaus (or Titchener) illusion.
It is an illusion of relative size (or more strictly, area). Here the
formal relationship between the parts of the image leads the small white
circle (which is the same size in both images) to seem larger in the
structural context of the tiny black circles than amongst the large black
circles. There is no shortage of examples of the role of structural context
amongst the geometrical illusions which can be found in psychology textbooks
so no further examples of the role of structural context will be discussed
here.
At this point it is useful to introduce schema theory briefly.
A schema (plural 'schemata' or 'schemas') is a kind of mental template or
framework which we use to make sense of things.
Particular circumstances seem to activate appropriate schemata, which
set up various standard expectations about such contexts. Such schemata
develop from experience. They help us to ‘go beyond the information given’
(as Jerome Bruner famously put it) by making assumptions about what is
usual in similar contexts. They allow us, for instance, to make
inferences about things which are not currently directly visible. The
application of schemata and the expectations which they set up
represents 'top-down' processes in perception (whilst the activation of
schemata by sensory data is a 'bottom-up' process). A good example of the
role of top-down processes is where you think that you recognize someone
in the street and then realize (from sensory data) that you are wrong.
We are often misled in this way by situational contexts, by wishful
thinking and so on, ignoring contradictory sensory data in favour of our
expectations.
In an experiment by Brewer and Treyens (1981), individual participants
were asked to wait in an office. The experimenter said that this was his
office and that they should wait there whilst he checked the laboratory to
see if the previous participant had finished. After 35 seconds, he
returned and took the participant to another room where they were asked to
recall everything in the room in which they had been waiting. People showed
a strong tendency to recall objects consistent with the typical ‘office
schema’. Nearly everyone remembered the desk and the chair next to it. Only
eight out of the 30 recalled the skull (!), few recalled the wine bottle
or the coffee pot, and only one recalled the picnic basket. Some recalled
items that had not been there at all: 9 remembered books. This shows how
people may introduce new items consistent with the schema.
In an experiment by Baggett (1975)
participants were shown a series of simple line drawings telling a story.
One story showed a long-haired man entering a barbershop, then sitting in
the barber’s chair, and finally leaving the shop with shorter hair.
In a later test they also saw a picture showing the actual haircut, which
had not been present originally. People were fairly good at remembering
that this picture had not been present if the test followed immediately
after the initial showing. However, if the test occurred a week after the
initial presentation most people claimed that they had seen the
haircutting picture in the original sequence. This shows the way in which
we incorporate in our memories inferences derived from our schemata. This
experiment was concerned with memory rather than perception, but it is
difficult to separate these processes if you take the stance that no
perception is 'immediate'.
Evidence that Indians have a different manner of looking at the world can
be found in the contrast between the ways in which Indian and non-Indian
artists depict the same events. That difference is not necessarily a matter
of 'error' or simply a variation in imagery. It represents an entirely
individual way of seeing the world. For instance, in a sixteenth-century
anonymous engraving of a famous scene from the white man's history an
artist depicted a sailing vessel anchored offshore with a landing party of
elegantly dressed gentlemen disembarking while regal, Europeanized Indians
look on - one carrying a 'peace pipe' expressly for this festive occasion.