This is post no.3 on mental imagery. Post no. 1 is here
In 2005, a 65 year old retired building inspector approached
neurologist Adam Zerman with the complaint that following coronary angioplasty
he no longer could form mental images.
Dr. Zeman could not find any description of such a phenomenon in the
literature. He tested this man with a
series of tests. Apparently, this man
had good memory for his age, and good performance in a variety of cognitive
tests. The only problem he had was his
inability to form mental images.
Dr Zeman and his team showed the man pictures of well known people
and asked him to identify them. He did
that easily and when doing so, he had activation in the same brain areas that
are activated during visual processing in most people. But when he read names of known people and
was asked to form a visual image of their faces, he said he couldn't do
it. The areas in the brain that are
usually activated during visual imagery were not activated in his brain during
this task.
Thus, beyond the subjective report of that man about his loss of
the ability to form mental images, researchers saw that brain areas normally
activated during the formation of mental images were not activated in his
brain. Nevertheless, he was able to
perform tasks that allegedly require the formation of mental images. He could state the color of the eyes of a well
known person. He could say which letters
in English have downward "tails" (like the letters "g" or "j"). Apparently, he performed these tasks in a
different way, without mental imagery.
Journalist Carl
Zimmer wrote about this research in the New York Times in 2015. Following his article, people approached
Dr. Zeman and reported having the same
phenomenon (without the coronary angioplasty).
Some of these people discovered for the first time that they were
different in this respect from most people.
Blake Ross, a writer and programmer, a
former Director of Product at Facebook, and the cofounder of Firefox, wrote this in his facebook page:
"If
you tell me to imagine a beach, I ruminate on the “concept” of a beach. I know
there’s sand. I know there’s water. I know there’s a sun, maybe a lifeguard. I
know facts about beaches. I know
a beach when I see it, and I can do verbal gymnastics with the word itself."
"But
I cannot flash to beaches I’ve visited. I have no visual, audio, emotional or
otherwise sensory experience. I have no capacity to create any kind of mental
image of a beach, whether I close my eyes or open them, whether I’m reading the
word in a book or concentrating on the idea for hours at a time—or whether I’m
standing on the beach itself".
Ross writes that he
does not usually remember dreams, and when he does, there is no visual or
sensory component to them. He has
difficulties navigating directions. When
he reads a book, he skips the descriptions.
He has trouble remembering events from his own past (retrieving episodes
from his episodic memory).
Apparently, people who
cannot form mental images (a condition named APHANTASIA) are at one end of a
spectrum. Galton, the great 19th
century scholar, who was one of the
founding fathers of the study of intelligence, noticed the existence of
individual differences in the ability to form mental images. Contemporary researchers argue these differences encompass three aspects:
1) Imagery Vividness. Mental Imagery vividness relates to the
clarity of the mental images evoked by an individual or the liveliness and similarity to the
actual percept.
2) Imagery
Control. This is the extent to which one can manipulate, transform, and
hold images in mind at will. Imagery
control is the individual’s ability to self-generate a mental image or to
perform certain manipulations, such as mental rotation.
2) Imagery
Processing Style. Some people form detailed images of objects. Others tend to form images of relations
between objects in space (for example, a mental map). People who tend to form object images tend to
form relatively static mental pictures, which are detailed and highly vivid. People who tend to create images of relations
between objects in space tend to form dynamic images.
These differences (in the general ability to form mental images and
in these three aspects) are usually measured with questionnaires, like the ones in this paper.
What are the possible implications of this to the functioning of a
child in school? To be discussed in the next post.
Zeman, A. Z., Della Sala, S., Torrens, L. A., Gountouna, V. E.,
McGonigle, D. J., & Logie, R. H. (2010). Loss of imagery phenomenology with
intact visuo-spatial task performance: a case of 'blind imagination'.
Neuropsychologia, 48, 145-155.
D’Argembeau, A., & Van der Linden, M. (2006).
Individual differences in the phenomenology of mental time travel: The effect
of vivid visual imagery and emotion regulation strategies. Consciousness and cognition, 15(2), 342-350.
Woojin Lee, Ulrike Gretzel.
Individual Differences in Mental Imagery Ability: Implications for
Online Media Consumption.
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