Perception, Attention and Performance, and Mental Imagery
Part I: Perception
A. Visual Perception in the Brain
Processing visual information requires a significant neural investment in humans.
This investment in vision is a part of what we "inherited" from primates, who have
evolved to devote up to 50% of their brains to processing visual information. The
massive investment supports humanity's capacity to perceive the world. In order to
process visual information, humans have a significant brain investment. Our
"inheritance" as primates, who have evolved to dedicate as much as 50% of their brains
to visual processing, includes this investment in vision. The vast investment is what
allows humans to see the world. This is clearly illustrated by people who have visual
agnosia, a disorder in which visual recognition is impaired yet they are not blind due to
injury to certain brain regions.
One soldier with visual agnosia had brain damage as a result of unintentional
carbon monoxide exposure. He was able to identify objects based on their feel, smell, or
sound, but he was unable to tell a circle from a square in an image or distinguish between
faces or letters. On the other hand, he was able to distinguish between different light hues
and intensities as well as the motion of an object. He could still register visual
information with his sensory system, but due to brain damage, he was unable to translate
visual information into perceptual experience. This instance demonstrates that perception
entails much more than merely registering sensory data.
Apperceptive or associative agnosia are the two main categories used to describe
visual agnosia. Individuals with apperceptive agnosia, like the soldier who just spoke, are
unable to recognize or sketch basic forms like circles or triangles. Associative agnosia
patients, on the other hand, may successfully replicate drawings of extremely
complicated things and are able to recognize simple shapes. Even after duplicating
drawings of complex items, they are unable to recognize them. The patient was able to
draw this object reasonably accurately, but was unable to identify it as an anchor. The
early processing of information in the visual system is generally thought to be impaired in
patients with apperceptive agnosia. However, it is believed that patients with associative
agnosia have problems with pattern recognition, which happens later, despite having
intact early processing.
B. Early Visual Information Processing
The eye is where early visual information processing starts. The retina, the eye's
innermost layer of cells, receives light that enters the eye. The retina's photoreceptor cells
contain light-sensitive molecules that change structurally in the presence of light,
triggering a photochemical reaction that transforms light into neurological impulses.
Cones and rods are the two different categories of photoreceptors found in the eye. Cones
produce excellent resolution and are involved in color vision (i.e., greater visual acuity).
The rods provide worse resolution and lack color information, but they require less light
energy to respond. They are therefore mostly to blame for the blurrier, black-and-white
vision we experience at night. The fovea is a little region of the retina where cones are
particularly dense. As we focus on something, we shift our eyes so that the picture of the
thing falls on the fovea, allowing us to fully utilize the high resolution of the cones in the
thing's perception. Foveal vision picks up minute details, whereas peripheral vision,
which encompasses the rest of the visual field, picks up more general information, such
as movement.
The optic nerve, whose axons exit the eye and establish the photoreceptor cells'
synapses with bipolar cells and these cells with ganglion cells, travels from the eye to the
brain. Each eye's optic nerve has roughly 800,000 ganglion cell axons in total. The cell's
receptive field, which is a discrete area of the retina, serves as the source of information
for each ganglion cell. The neuronal firing rate on the ganglion cell's axon typically
encodes the intensity of light stimulation in that area of the retina.
The ganglion cell axons from the retina's interior (the sides closest to the nose)
cross over and proceed to the opposing side of the brain at the optic chiasma, where the
optic nerves from the eyes converge (axons from the inside of the left eye go to the right
side of the brain, and axons from the inside of the right eye go to the left side of the
brain). The retinal outer segments' axons continue to the same side of the brain as the eye
they originate from. This indicates that the left hemisphere of both eyes is related to the
right hemisphere, and vice versa. The lens concentrates light from the right half of the
visual field onto the left half of each eye and light from the left side of the visual field
onto the right half of each eye. As a result, information about the left side of the visual
field is transmitted to the right brain, and information about the right side is transmitted to
the left brain.
The fibers from the ganglion cells attach to cells in different subcortical areas
once they have entered the brain. The primary visual cortex is related to these subcortical
regions. Although there are numerous other visual areas, the primary visual cortex is the
first cortical area to receive visual data. The fovea is disproportionately represented, but
the periphery is underrepresented. Information typically travels down two paths from the
primary visual cortex: a "what" channel and a "where" pathway. The temporal cortex's
"what" visual circuit leads to areas with a focus on object recognition. The parietal brain
areas that are skilled at representing spatial information and coordinating vision with
action are reached through the "where" visual pathway. According to research, monkeys
with lesions in the "what" circuit have difficulties learning to recognize items, but
monkeys with lesions in the "where" pathway have trouble identifying certain locations.
Patients with parietal lobes intact and agnosia due to temporal lobe impairment can
frequently act appropriately to unfamiliar objects. One patient, for example, was able to
grab a door handle she had never seen before.
C. Information Coding by Neurons in the Visual System
The ganglion cells in the retina are responsible for encoding information,
according to Kuffler's (1953) research. Even in the absence of light, these cells often fire
at some spontaneous rate. The spontaneous rates of firing of some ganglion cells will rise
if light shines on a small area of the retina in the cell's receptive field. The spontaneous
firing rate will, however, slow down if light is present in the area immediately
surrounding this sensitive location. The spontaneous firing rate is not altered by light that
is further from the center, neither is it increased. The term "on-off cells" refers to
ganglion cells that react in this manner. Moreover, there are ganglion cells that are off-on,
meaning that light in the core of the cell slows down spontaneous firing while light in the
periphery speeds it up. Similar reactions are seen in cells of the lateral geniculate nucleus.
When Hubel and Wiesel (1962) studied the cat's primary visual cortex, they
discovered that ganglion cells and cells in the lateral geniculate nucleus had receptive
fields that were different from each other. The circular receptive fields of the on-off and
off-on cells are absent from these receptive fields, which are uniformly elongated in
shape. Light on one side of a line makes edge detectors react positively, while light on the
other side makes them react negatively. If a light edge exactly follows the boundary, they
react most strongly. Light in the center of a room affects bar detectors favorably, while
light at the periphery affects them poorly. Hence, if a bar of light just partially covers the
center of a bar detector with a positive center, the sensor will react most. Edge and bar
detectors are both precise in terms of position, inclination, and width. In other words,
they only react to stimulus in a limited visual field, to bars and edges in a limited range of
orientations, and to bars and edges of a specific width. Diverse detectors are set to
various angles, widths, and positions. Any bar or edge, regardless of location in the visual
field, direction, or width, will cause some subset of detectors to respond maximally.
D. Depth and Surface Perception
To enable visual perception of the world, a significant amount of information
processing must still be carried out after the visual system has recognized edges and bars
in the surroundings. The precise location of such edges and bars in space, as well as their
depth or relative distance, must be known. The main issue is that the information
presented on the retina is naturally presented in two dimensions (2-D), whereas we need
to create a three-dimensional (3-D) representation of the world. In addition to features
like size, position, and lighting, the visual system also uses cues like motion parallax,
stereopsis, and texture gradient to estimate distance.
When objects that we normally assume to be roughly equal in size and evenly
spaced appear to regularly shrink in size and pack closer together, it serves as a cue to our
perception of distance. For example, if you're standing on a balcony and looking out over
a large crowd of people, the crowd's apparent size shrinks and apparent density rises with
distance. Our unconscious assumption that the ovals or lines are roughly equal in size and
spacing (despite our knowledge that these elements are all equally distant on a flat page)
leads to the texture change, which results in the regular decrease in size and distance
between the ovals and lines from bottom to top.
The capacity to perceive 3-D depth through stereopsis is based on the fact that
each eye sees the world slightly differently. This is made possible by the 3-D glasses used
to see some movies and displays in theme parks by filtering the light from a single 2-D
source (say, a movie screen). The 3-D glasses allow each eye to see only one image,
which is what that eye would see if the scene were in 3-D rather than on a flat 2-D movie
screen. Two slightly different images are projected onto the screen. Stereopsis can give
the impression of a three-dimensional structure, which can be quite persuasive.
When the observer or objects in a scene are moving, motion parallax gives
information about the 3-D structure of the scene: In comparison to images of nearby
objects, those at a distance will move across the observer's retina more slowly. Try
closing one eye and keeping your head still while looking at a nearby tree for an
intriguing demonstration. Without stereoscopic information, the image will appear quite
flat and it will be difficult to discern the relative depths of the leaves and branches. The 3-
D structure of the tree, however, will suddenly become apparent if you turn your head
because the images of nearer leaves and branches will slide over the photos of farther-off
ones, clearly indicating depth.
E. Object Segmentation
Segmenting objects is a significant challenge in creating a representation of the
world. We need to know which lines and bars combine to make objects; simply knowing
where they are in space does not suffice. According to a set of rules known as the gestalt
principles of organization—named after the Gestalt psychologists who first developed
them—we classify materials into units. These classifications aid in establishing object
boundaries. Below are the basic principal of gestalt:
1. Principle of proximity
2. Principle of good continuation
3. Principle of closure and good form
4. Principle of similarity
It is possible to expand the gestalt organization principles to explain how
increasingly intricate 3-D structures are viewed. People essentially take advantage of the
gestalt concept of excellent continuation: Viewers do not group these components
together because the lines at the locations of concavity do not make excellent natural
extensions of one another.
F. Visual Pattern Recognition
Before we view the world, there is still a significant step to be taken, though: We
must also determine what these items are. Pattern recognition is the process of doing this.
The question of how we identify letters, a unique form of item, has received a lot of
attention in this area of study. How can we identify a presentation of the letter A as an
instance of the pattern A, for example? Before moving on to a more general examination
of how we recognize the wide diversity of items in our world, we will first address
pattern recognition with regard to letter identification. Using template matching may be
the simplest technique to spot a pattern. According to the template matching theory of
perception, the brain faithfully receives a retinal image of an item and then makes an
effort to directly compare the image to multiple templates that it has previously stored.
The essential notion behind, for instance, recognizing a letter of the alphabet is
that the perceptual system compares the image of the letter to the templates it has for
various patterns. Notwithstanding these challenges, template matching is a technique
utilized in machine vision, where algorithms have been developed for rotating, stretching,
and other picture manipulations to match. In fMRI brain imaging, template matching is
also utilized. The physical structure of each human brain varies, just as it does with each
human body. In most cases, when researchers make claims about specific brain regions,
they mean that each participant's brain had that pattern present in the same location,
according to their claims. They map each brain to a reference brain using an advanced
computer-based 3-D template-matching process to confirm that it is the same location.
Despite considerable progress, there appear to be restrictions on how well computers can
use template matching to detect patterns.
Part II: Attention and Performance
A. Serial Bottlenecks
According to psychologists, the processing of information by human’s
experiences sequential bottlenecks at which time it becomes impractical to carry on with
parallel processing. For instance, it is well acknowledged that parallelism in the motor
systems has its limits. The majority of us can carry out two distinct acts concurrently
when they need different motor systems (such as walking and chewing gum), but we
struggle to make one motor system work twice as hard. For instance, even though we
have two hands, we only have one method for moving them, making it challenging to
coordinate the movement of both hands at once.
How early do bottlenecks occur? Do they happen before we receive the stimuli,
after we perceive the stimulus but before we think about it, or simply right before a motor
action is required? This is one topic that psychologists have been trying to answer. There
are some tasks that simply cannot be completed simultaneously, according to common
sense. To multiply and add two digits at the same time, for example, is almost
impossible. Where the information processing bottlenecks actually are is still a mystery.
Depending on where they contend bottlenecks occur, several hypotheses about their
location are referred to as early-selection theories or late-selection theories. Anytime
there is a bottleneck, our cognitive processes have to decide which information to focus
on and which to disregard.
Goal-directed attention, sometimes referred to as endogenous control, and control
by stimulus-driven processes represent a key division in the study of attention (stimulus-
driven attention, sometimes called exogenous control). The white thing simply caught our
attention; we weren't trying to pay attention to it. Our guide might begin to make a
statement about a "small animal playing a musical instrument," though. With a goal in
mind, we will now scan the image in search of the thing being described. Goal-directed
attention is managed by somewhat distinct brain circuits than stimulus-driven attention.
For instance, according to data from brain imaging, the stimulus-driven attentional
system is more right lateralized than the goal-directed attentional system. It is possible to
distinguish (roughly) between the brain regions that process the information selected and
those that are engaged in attention, or the regions that choose which information to
process. Information processing in areas like the visual cortex and auditory cortex is
influenced by the parietal cortex. Processing in the motor area and more posterior regions
is influenced by prefrontal regions. The dorsolateral prefrontal cortex and the anterior
cingulate cortex are two of these prefrontal areas.
B. The Filter Theory
Broadbent (1958) put up an early-selection theory known as the filter theory. His
fundamental presumption was that sensory information passes through the system until
some sort of bottleneck is encountered. At that time, an individual choose which message
to process based on a physical trait. The other information is purportedly excluded by the
person. The notion put forth in a dichotic listening exercise claimed that the message to
each ear was registered, but that at a later time the participant would choose one message
to listen to base on the specified ear, filtering out the message in the other ear. We choose
which speaker to listen to at a crowded party based on the speaker's voice pitch or
volume, among other physical traits. The idea that we choose a message to process based
on physical traits like ear or pitch is a key component of Broadbent's original filter
model. This theory made some sense from a neurophysiological perspective. The brain
receives messages from each ear via several nerves. Also, the frequencies that each nerve
transmits from each ear differ. So, we can speculate that the brain chooses particular
nerves to "pay attention to" in some way.
The physical qualities of a communication can surely influence a person's
decision to pay attention to it, but semantic content can also influence a person's decision
about which messages to analyze. In one experiment, Gray and Wedderburn (1960), who
were at the time Oxford University undergraduate students, showed that participants
could employ meaningfulness to follow a message that jumped back and forth between
the ears. In his study, Treisman (1960), he examined a scenario in which participants
were told to follow a certain ear. Before it became a random string of words, the message
in the shadowy person's ear had some meaning. The participant's attention was diverted
to one ear as the important information abruptly moved to the other. Contrary to
instructions, several participants switched ears and kept listening to the important
message. The dark ear kept being followed by others. As a result, it appears that
sometimes people choose which message to follow based on a physical trait (for example,
a specific ear), while other times they choose based on semantic content.
C. The Attenuation Theory and a Late-Selection Theory
Treisman (1964) suggested an early-selection theory that is a variation of the
Broadbent model and has come to be known as the attenuation hypothesis in order to
explain these kinds of outcomes. Based on their physical characteristics, this model
proposed that some communications would be attenuated (weakened), but not completely
filtered out. Participants would thereby reduce processing of the signal from the
unattended ear but not completely eliminate it in a dichotic listening task. Any
communication, attenuated or not, could be subject to semantic selection criteria. It
would be more difficult, but still viable, to use these selection criteria if the message were
attenuated. According to Treisman (1978), in her experiment, the majority of participants
actually persisted in shadowing the recommended ear. It appears that participants
preferred to pay attention to the message that wasn't being attenuated rather than
switching their focus by using semantic criteria.
J. A. and D. Deutsch's late-selection hypothesis, which stated that all the
information is processed entirely and without attenuation, had previously offered a
different explanation. They claimed that the reaction system, not the perceptual system, is
where the capacity constraint lies. They were arguing that even while humans can hear
and understand several messages, they can only express one at a time. In order to choose
which message to shadow, humans need a basis. They will change their ears to hear the
message if they utilize meaning as the criterion (either in agreement with or in defiance
of instructions). When choosing what to focus on, they will follow the chosen ear if they
use the ear of origin. Both the early selection attenuation theory and the late-selection
theory make the assumption that there is a processing filter or bottleneck. According to
Treisman's attenuation hypothesis, a perceptual filter chooses which message to focus on
(message #1), and as a result, the unselected message (message #2) is attenuated (dashed
arrows). As a result, only message #1 is spoken completely evaluated. The late-selection
theory, on the other hand, postulates that a response filter kicks in after both messages
have been thoroughly examined.
D. Visual Attention
In the case of auditory information processing, visual information processing
exhibits a bottleneck. The acuity of the retina varies, with the fovea, a very small region,
having the highest acuity. The fovea only detects a small portion of the visual field,
compared to the human eye's extensive registration of the entire visual field. As a result,
when we pick where to focus our vision, we also decide how much of our visual
processing capability to give to that particular area of the visual field. The amount of
resources that are allocated to processing other areas of the field is therefore constrained.
Normally, whatever area of the visual field we are concentrating on is what we are paying
attention to.
The area of the visual field being processed by the fovea is not necessarily the
same as the focus of visual attention. While attending to another, non-foveal portion of
the visual field, people can be coached to fixate on one area of the visual field, causing
the concentrated picture of that area to fall on the fovea. Humans need to move our
attention around the visual field to monitor the visual information in order to interpret a
complicated visual scene.
E. The Neural Basis of Visual Attention
There is evidence to suggest that the neurological processes governing visual and
aural attention are extremely similar. Visual attention focused on a particular spatial area
seems to boost the cortical signal from that region, just as auditory attention focused on
one ear boosts the signal from that ear. Within 70 to 90 ms of the start of a stimulus, the
visual cortex exhibits a discrete neural response that may be identified using ERP data
when a person pays attention to a specific spatial position. As opposed to this, we do not
observe a response for longer than 200 ms when a person is attending to a specific object,
such as a chair rather than a table, for example. As with auditory attention, it therefore
seems to require more effort to focus visual attention on information rather than on
external details.
F. Inattentional Blindness
People believe that we are generally aware of everything around us, but research
shows that this is primarily a delusion – we only pay attention to what we are aware of.
According to Mack and Rock (1998), the phenomenon known as inattentional blindness
describes how, when we are not paying attention to anything, we frequently fail to notice
what is directly in front of us. Mack and Rock used a perceptual experiment in which
participants had to determine whether the horizontal or vertical bar of a cross was longer
as their famous example of this phenomena. Following a number of trials, a surprise trial
would be conducted in which the cross and an extra stimulus, such as a rectangle,
appeared on the screen. Several test subjects did not acknowledge perceiving the
additional stimulus when questioned after the trial. In contrast to the 5000 subjects Mack
and Rock assessed in their initial study, this experiment only involved one surprise trial
for each person.
When participants were looking for a target letter in a display with distracter
letters that were either the same size as the target letter (a high-difficulty job) or smaller
than the target letter (a low-difficulty task), Raveh and Lavie (2015) played a surprise
tone. Compared to the low-difficulty condition, where failure rates were just 18%,
participants in the high-difficulty condition consistently failed to recognize the tone in
55% of the trials. This condition was identified by the researchers as inattentional
deafness. Participants found it challenging to determine what was in the unattended ear
while completing the intensive shadowing task. Ongoing discussion surrounds the exact
nature of what takes on when participants are unable to recognize the surprise stimulus.
The consequences of object presentation can be seen even when the presentation is not
observed, according to Wolfe (1999), who contended that what was actually happening
was a case of inattentional amnesia, where the object was actually noticed but then
promptly forgotten.
G. Object-Based Attention
When people concentrate their attention on specific things rather than general
areas of space, this is known as object-based attention. One study showing that people
occasionally find it simpler to attend to an object than to a location is that of Behrmann,
Zemel, and Mozer (1998). Participants had to determine whether the items' ends had the
same amount of bumps. When the bumps were on the same object, participants rendered
these decisions more quickly. This result was obtained despite the fact that, if attention
were dependent on space, judgment should have been made easier when the bumps were
on separate objects because their ends were situated closer together. As opposed to
attending to one location at a time, Behrmann et al. contend that participants focused on
one object at a time. As a result, when there was no need for participants to switch their
attention between things, judgements were made more quickly. As soon as the stimulus
was present for a limited time, the benefit of the within-object effect vanished. The
development of object-based attention must take time, according to this.
An additional indicator of object-centered attention is a phenomena known as
inhibition of return. According to research, it is a little tougher for us to refocus our
attention to a specific area of space after we have previously focused on it. We take
longer to restore our eyes to position A after moving them to site B than to a different
location, such as C. Also, when we shift our focus without shifting our eyes, this holds
true. In certain circumstances, this phenomena is advantageous. The visual system
appears to have the ability to focus attention on either objects or places in space. It's
intriguing that object-based attention appears to be more heavily influenced by the left
parietal areas, but location-based focus appears to be more heavily influenced by the right
parietal regions. Contrary to the location-based abnormalities that I have mentioned in
patients with right parietal damage, patients with left parietal damage tend to have
difficulties concentrating attention on objects. Also, when people focus on items rather
than on places, the left parietal regions are more active. The right parietal area is in
charge of focusing on global aspects, while the left parietal region is in charge of
focusing on local features.
H. The Stroop Effect
In addition to requiring little or no central cognition to operate, automatic
processes also seem to be challenging to stop. Word recognition for experienced readers
is an excellent example. It is nearly hard to glance at a common term without reading it.
The Stroop effect, named for the psychologist J. Ridley Stroop who originally
demonstrated it, has been used to study this high tendency for words to be identified
automatically. Participants must identify the color of the ink used to print the text in the
task. The Stroop effect is examined under three different settings, which are represented
by the three columns. The words in the first column show a neutral or control situation
where there are no color terms. The congruent condition, where the words are color
words that match the color of the ink they are printed in, is illustrated by the second
column. The conflict situation when the words are color words that do not match their ink
colors is shown in the third column.
In an adaptation of the Stroop task, MacLeod and Dunbar (1988) investigated the
impact of practice on performance. They made use of an experiment where participants
were taught to connect color names with arbitrary shapes. After showing the participants
test shapes, the researchers asked them to either name the color that went with the shape
or its real color. The same three circumstances were used as in the original Stroop
experiment:
1. Congruent: The shape's name and color were both the same color.
2. Control: When participants were asked to describe a color for a taught shape,
outlined white copies of the forms were shown; when they were asked to
name the shape's real color, colored squares were shown. (There was no color
connected to the square shape.)
3. Conflict: The shape's hue was different from what it was called.
Part III: Mental Imagery
A. Verbal Imagery Versus Visual Imagery
There is growing evidence from cognitive neuroscience that many brain regions
are engaged in mental imagery. This information comes from both studies of patients
with injury to different brain regions and examinations of how normal people's brains
respond to different tasks using imaging. Roland and Friberg (1985) discovered many of
the brain regions that have been studied in later study in one of the earliest investigations
of brain activation patterns during mental imagery. Researchers observed changes in
brain blood flow as individuals either mentally practiced a nine-word circular jingle or
imagined themselves navigating unfamiliar streets in their areas.
Both the parietal-temporal region of the posterior cortex and the prefrontal cortex
close to Broca's area were activated when participants performed the verbal jingle task.
The parietal cortex, occipital cortex, and temporal cortex all became active as participants
worked on the visual task. These regions are all involved in attention and visual
perception. So, some of the same brain regions that are active when processing actual
speech or visual information are also active when people process verbal or visual
imagery.
B. Mental Rotation
Understanding how things will seem from various angles is one of the purposes of
mental imagery. The idea that one mentally rotates items to alter perspective is one that
people frequently have. In a lengthy series of mental rotation studies, Roger Shepard and
his associates participated. One of the pioneering studies of the functional aspects of
mental images, their work has had a significant impact. It's significant to note that
Shepard's dream, from which this research took its cue, was the source of inspiration for
this study. Shepard recalled having seen a 3-D structure move through space when he
awoke. The rest, as they say, is history. He persuaded Jackie Metzler, a Stanford graduate
student in her first year, to investigate mental rotation.
Science published a report on their initial experiment. Pairs of 2-D renderings of
3-D objects were shown to the participants. They had to decide if the objects were
identical or different only in orientation. Participants claimed that they mentally rotated
one of the objects in each pair to see whether it could be made congruent with the other
object in order to determine whether the two shapes matched. The findings demonstrate
that participants rotated their internal, three-dimensional images of the object.
Participants took longer to complete the mental rotation as the angle of difference
between the two objects increased.
Many studies had already looked into how quickly people can mentally rotate a
variety of things, and they have generally shown that the speed at which people can rotate
an item depends on how far apart the axes are. Also, a number of brain imaging studies
have examined the areas of the brain that are engaged during mental rotation. A variety of
tasks have consistently involved activating the parietal area. In order to focus on space,
the parietal area is crucial. A few jobs call for the stimulation of additional regions.
Kosslyn, DiGirolamo, Thompson, and Alpert, for instance, discovered in 1998 that the
motor cortex was activated when one imagined rotating their hand.
C. Image Scanning
We also frequently inspect our mental representations for important details when
using them. One common response when asked how many windows they have in their
home is to mentally scan each room in the house to count the number of windows.
Researchers have investigated if, rather than simply retrieving abstract information,
people are scanning visual representations in such tasks. Consider the question of
whether we are actually "seeing" every window in the space or merely recalling their
number.
The scanning of visual pictures was the subject of a significant set of experiments
by Brooks in 1968. Participants were instructed to scan fictitious diagrams. For instance,
the participant was instructed to scan an imagined block F from a predetermined
beginning point and in a predetermined direction, classifying each corner of the block as
either a point on the top or bottom (received a yes response), or as a point in between
(assigned a no response). The proper order of responses in the example (starting with the
starting corner) is yes, yes, yes, no, no, no, no, no, no, no, yes. A bird in the hand is not in
the bush is one of the lines that Brooks provided participants for a nonvisual contrast
exercise. While keeping the statement in their minds, participants had to quickly scan it to
determine whether or not each word was a noun. The manner in which participants gave
their responses was a second experimental variable. Participants gave one of three
responses: Saying yes or no, tapping with the left and right hands, or pointing to certain
Ys or Ns on a piece of paper are all acceptable methods of responding. There was a
conflict between scanning a mental image and scanning a tangible visible thing. The idea
that when people scan a mental image, they are scanning a representation that is
equivalent to a physical picture, is highly supported by this study.
The visual nature of the pointing task itself is not the cause of the interference.
The issue is actually spatial in nature rather than purely visual, and it is brought on by the
incongruent directions in which participants were required to scan both the external
visual array and the internal image. This interpretation is supported by results from a
different experiment in which Brooks discovered a similar interference when subjects
closed their eyes and scanned a range of raised Ys and Ns with their fingertips to indicate
yes or no. The actual sensations in this instance were tactile rather than visual. As a
result, the conflict is spatial rather than just visual.
D. Visual Imagery and Brain Areas
According to brain imaging research, the same areas of the brain are engaged in
both visual perception and visual imagining. The parietal regions that are engaged in
attending to places and objects are also involved in mental rotation, as was previously
mentioned. An experiment conducted by O'Craven and Kanwisher in 2000 provides
additional evidence of how closely the brain regions engaged by images and perception
match. The parahippocampal place area (PPA) of the temporal brain responds
preferentially to images of places, while the fusiform face area (FFA) of the temporal
cortex responds preferentially to images of faces (i.e., indoor or outdoor scenes).
Participants were given the option of viewing or imagining faces and scenes by O'Craven
and Kanwisher.
Both when participants were observing and when they were picturing, the same
regions were engaged. The FFA was more active whenever the subjects saw or imagined
a face, and this activation subsided whenever they saw or imagined a setting. On the
other hand, there was decreased activation in the PPA when they saw or imagined faces.
Although a little weaker, the reactions during visualization were remarkably similar to
the responses during perception. The behavioral evidence we have discussed indicating
that it is more challenging to process an image than a genuine experience is consistent
with the fact that the response was weaker during visualization.
Other studies demonstrate that processing of visual images activates cortical areas
involved in high-level visual processing. The activation of the primary visual cortex,
where visual information enters the brain for the first time, is less obvious from the
evidence, though. The primary visual cortex was discovered to be activated during
images in the O'Craven and Kanwisher (2000) study. These findings are significant
because they imply that visual imagery involves only a few basic perceptual mechanisms.
The main visual cortex is not always activated, according to other studies.
E. Cognitive Maps
Visual imagery also aids in our comprehension and retention of the spatial
organization of our surroundings. Cognitive maps are terms used to describe our mental
maps of the world. Cognitive maps make the link between imagery and behavior very
clear. When we prepare for how we will get from one place to another and when we
actually move between locations, we frequently find ourselves picturing our
surroundings.
There is a significant difference between cognitive maps that are survey maps and
those that are route maps. A route map is a path that identifies specific locations but lacks
spatial data. Hence, if your route from site 1 to location 2 were blocked, you wouldn't
have a general notion of where place 2 was, making it impossible for you to plan a
diversion. In contrast, a survey map—which is essentially a spatial depiction of the
environment—contains this kind of data. To enable both sorts of mental representations
of space, online mapping systems often offer both a route map and a survey map when
you ask them for instructions.
At Santa Monica, California, the enormous, confusing Rand Corporation Building
was the subject of an investigation by Thorndike and Hayes-Roth in 1982. Individuals
that work in the Rand Building quickly learn how to go from one particular location in
the building to another, such as from the supply department to the cashier. Such
information functions as a road map. Yet, workers typically needed years of building
experience to acquire survey-map expertise, such as knowing how to get to the snack bar
from the executive conference room (due south).
