This is a fourth (and
last?) of a series of posts on mental imagery.
People don't always like to see movies
based on books they have read. They are
afraid that the movie would look different than the way they saw things in
their mind's eye. Sometimes they express
disappointment at a character's
appearance: "He is not
supposed to look this way!" When
reading we form mental images of the characters and the surrounding. We don't only "know" how things
look, by the descriptions in the book.
We "see" them in our mind's eye.
When reading, we do not only form visual
images but auditory images as well. A
few years ago my daughter burst out laughing when reading a book
(silently). It turned out that she read
the question "What happened?" as a shout, and then saw that the next
words were "he whispered". At
first, the character was shouting in her mind's ear.
Does it mean that individual differences
in the ability to form mental images affect their reading comprehension? Does a person who forms mental images which are
less vivid or precise understand the scene less well? Would a person who finds it hard to control
the mental image of a scene (for example, to see it from different angles, to
update the image when new information unfolds) understand it less well?
When we remember events from our past, we
may recall some of them in great detail.
For instance, when we recall an event that took
place by the beach, we see with our mind's eye the specific beach where the
event happened, and the people and objects that participated in it. We can form auditory images of the seagull
cries, olfactory images of the salty smell of the sea, and these mental images
may help us to remember what we thought and felt during the event. Mental images are probably part of the way we store and retrieve
information in memory.
As we've seen in the first post, mental
images are processed in brain areas devoted to perception. For example, when a person forms a visual
image he activates brain areas that are activated during visual perception. Furthermore: brain areas related to visual
perception are activated during retrieval from episodic memory (memory for our
life events). Thus damage to brain areas
that support visual perception leads both to visual imagery loss and to episodic memory loss. According to Dr. Zeman, people with permanent
attenuation in the ability to form visual
images are at a greater risk for poor memory for their life events. The opposite also seems to be true: people with extremely poor episodic memory
report having poor ability to form visual images.
What about thinking about the future and
decision making? The ability to remember
the past and to think about the future are linked. Episodic memory and the ability to project ourselves
into the future (to think about the future with ourselves in it) appear at a
similar period of development – around age four. People who, following brain damage, are not
able to remember their personal past usually have difficulty imagining possible
future experiences. Thus it's possible
that people who have difficulty forming mental images also have difficulty
imagining the future and projecting themselves into the future.
The ability to imagine the future affects
our ability to make decisions. Prof. Bence Nanay argues that we make decisions by
forming a mental image of each possible alternative and placing ourselves in
it. For example, if a child has
to choose an afterschool activity, he forms mental images of himself in each
activity. These images help him to make
the decision.
Ernest
argued in 1977 that individual differences in the ability to form mental images
can significantly influence a range of cognitive functions such as learning,
memory, perception and problem solving.
Yet
no correlation was found between the ability to form mental images (as reported
by questionnaires) and people's level of performance on tasks that allegedly
require imaging, for example, mental rotation, visual memory and visual
recognition. No correlation was found between the reported vividness of mental
images and people's performance in terms of speed or precision on visual
spatial tasks and on problem solving tasks that seem to require the formation
of mental images.
Galton wrote in the 19th
century: ‘Men who declare themselves
entirely deficient in the power of seeing mental pictures can nevertheless …
become painters of the rank of Royal Academicians’
How do we explain this? Here are several possibilities:
A.
People can perform tasks that allegedly require mental imagery in other
ways, without the formation of mental imagery.
These ways may be less effective, but they nevertheless enable them to
perform the tasks.
B.
Tests that supposedly require the formation of mental images do not
resemble everyday functioning. The
manipulations of imagery required in these tasks is different in kind and
complexity from manipulations of mental images in everyday life.
C.
People who report having no mental imagery do form images but are not
aware of it.
D.
Questionnaires that measure the quality of mental imagery measure different
phenomena than is measured by tests that allegedly require the formation of
mental images.
E.
Questionnaires that were used in some of the studies did not
differentiate between different kinds of mental images.
It's possible to identify two kinds of
mental imagery: mental imagery of
objects and mental imagery of spatial relations. The ability to form object imagery is the ability to image the form
of objects, their color, texture, scent and other details. This is the ability to form a mental image of
a rose in its full vividness and scent.
The ability to form
spatial relations imagery is the ability to form an image of the
relative placement of objects in space, the ability to mentally move the
objects in relation to each other and to image changes in objects. This is, for instance, the ability to image
the look of the whole garden, with shrub roses, trees, benches and so on. This is the ability to image where the shrub roses are placed relative to other objects in the garden, and the
ability to image the wind blowing the rose petals. Maybe these different kinds of images affect
performance on tests that require the formation of mental images in different
ways.
Sixth grade children
were given math word
problems and then were asked to describe the way they solved them. For instance, they solved the following
problem: "At each of the two ends
of a straight path, a man planted a tree, and then every 5 meters along the
path he planted another tree. The length of the path is 15 meters. How many
trees were planted?"
Children who used
spatial imagery used gestures in their descriptions that showed the spatial
relations between objects in the problem, or reported having spatial images of
the relations in the problem. For
example: "I had a [mental] picture
of the path, not the trees, and it had something 5 meters along, not trees,
just something." Children who used
spatial imagery also created drawings of the problem that depicted the
relations between objects.
Children who used
object imagery reported images of objects or people mentioned in the problems, and
not the relations between them. For
instance: "I saw the man planting a
tree".
Children who used spatial mental imagery did better on
the word problems than children who used object imagery. The
researchers argue that forming object images turns attention away from the
relations between objects in the problem.
In another study with adults, it was found that
scientists and engineers excel in spatial imagery and prefer spatial
strategies, whereas visual artists excel in object imagery and prefer
object-based strategies.
To sum up, mental
images assist in everyday functioning.
People differ in their ability to have mental images and in the kinds of
mental images they form. Different kinds
of mental images can help to perform different kinds of tasks. People who can't form mental images can
succeed in the same tasks, probably by using other strategies.
Zeman, A.,
Dewar, M., & Della Sala, S. (2015). Lives without
imagery–Congenital aphantasia. Cortex, 3.
Sheldon,
S., Amaral, R., & Levine, B. (2016). Individual
differences in visual imagery determine how event information is remembered. Memory, 1-10.
Hegarty,
M., & Kozhevnikov, M. (1999). Types of
visual–spatial representations and mathematical problem solving. Journal of educational psychology, 91(4), 684.http://www.nmr.mgh.harvard.edu/mkozhevnlab/wp-content/uploads/pdfs/types_visual1999.pdf
Kozhevnikov, M., Kosslyn, S., and
Shepard, J. Spatial versus
object visualizers: a new
characterization of visual cognitive style. Memory and Cognition 2005,
33(4), 710-726. http://nmr.mgh.harvard.edu/mkozhevnlab/wp-content/uploads/pdfs/spatial_versus2005.pdf
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