Clara Weber Cognitive Psychology 2019
Cognition - Exploring the science
of the mind
Daniel Reisberg
Sixth edition
Chapter 1 - The Science of the Mind
The cognitive revolution had two key ideas: (1) that the study of psychology could not study the
mental world directly and, (2) that the science of psychology must study the mental world if we
want to understand behaviour.
Wundt and Titchener came up with introspection, the act to look within and observe out mental
lives and experiences. However since introspection involves self-report, the unconscious events
are completely disregarded. Furthermore, introspection is subjective and cannot be used to test a
hypothesis therefore nowadays is mostly used as an observation that needs to be explained.
These concerns about introspection triggered psychologist to look into new methods which
obtained more objective data. This led to the behaviorist theory which dominated America the
early 20th century. Although this gave more objective data in terms of which stimuli triggers which
behaviour, it completely disregarded beliefs and other mental processes which were crucial
determinants of behaviour. How people act is shaped by how they perceive the situation and
understand the stimuli, which leads us back to understanding deeper cognitive processes.
A solution to this was suggested by Kant many years ago, called the transcendental method.
This involves beginning with the observable facts and then working backwards to figure out how
these effects came about. This led psychologists to study mental processes indirectly, relying on
the fact that they have visible consequences (e.g. response time, accuracy etc.) Once this was
established, psychologists could form hypotheses, collect data and so forth.
Working memory is the memory we use for information we are actively processing. One method
of testing working memory involves a span test. This requires a participant to have several letters
read out to him and he must recite them back in the same order. The number of letter is increased
until the person is unable to report them back accurately anymore (usually around 7 or 8 letters).
The span test also showed another valuable finding, being that often when letters are reported
back incorrectly, they are replaced with a similar sounding letter (e.g. D reported back as T). This
is because we get similar sound-alike confusions if the letters are represented visually through the
phonological buffer.
This finding cause researchers Baddeley and Hitch to propose the working-memory system,
which essentially shows that working memory has several parts. At the heart of this system is the
central executive which does most of the work, along side the assistants which are used for
temporarily storing information. One of these assistants is the articulatory rehearsal loop, which
helps us remember (rehearse) information whilst simultaneously absorbing new information. In
order to activate this we rely on subvocalisation (silent speech), which creates a representation
of the information in the phonological buffer.
Another type of task is the concurrent articulation task which involves taking a regular span test
whilst simultaneously saying “Tah-tah-tah” which inhibits subvocalisation. When completing this
task our working memory capacity decreases by half.
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,Clara Weber Cognitive Psychology 2019
The study of cognitive neuroscience involves the biological basis for cognitive functioning,
examining which biological mechanisms result in which type of performance. For example,
someone with anarthria is unable to produce overt speech, due to muscles in the mouth and
tongue being paralysed. However, these patients are still able to use the rehearsal loop and show
sound-alike confusions, indicating that inner speech does not come from the physical movement
of muscles but rather dedicated brain areas. This is part of neuropsychology, which focuses on
how various forms of brain dysfunction influence observed performance.
A deaf person uses ‘inner hand’ (convert sign language) instead of ‘inner speech’, thus they would
get disrupted when asked to wiggle their fingers during a memory task the same way a hearing
person would react to saying “tah-tah-tah”.
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,Clara Weber Cognitive Psychology 2019
Chapter 3 - Visual Perception
The process of seeing stats with light. Light hits the the surface of the eyeball, passing through
the cornea and the lens, where it then reaches the retina (the light sensitive tissue that lines the
back of the eyeball). The cornea and lens focus the incoming light through a set of muscles
surrounding the lens. These muscles tighten (for nearby objects) and relax (for distant objects) to
change the focus. The retina contains 2 types of photoreceptors: (1) rods and (2) cones. Rods
are sensitive to low light levels and are able to distinguish different intestines of light (brightness),
however they are colour-blind. Cones on the other hand are less sensitive to light, thus need more
of it to operate, however they are also sensitive to differences in colour. Cones come in 3 varieties
with sensitivity to specific wavelengths: (1) short, (2) medium and (3) long wavelengths. By
comparing the outputs from all 3 cone types, a specific colour is signalled. Furthermore, cones
allow us to see in detail, also known as acuity. When we want to look at a target in detail we will
point our eyes towards it, since this position allows the target to be cast onto the fovea (centre of
the retina). The centre of the retina is densely packed with cones, whereas the peripheral has no
cones and plentiful rods.
Rods and cones do not transport their information directly to the cortex, they first stimulate
several other cells. First they excite the bipolar cells, which excite the ganglion cells, a bunch of
cells spread across the retina with all their axons converging into what we call an optic nerve.
The optic nerve leaves the eyeball and carries the information to an area in the thalamus called
the lateral genticulate nucleus (LGN), from here the information proceeds to the occipital lobe.
Lateral inhibition is a process in which stimulated cells inhibit the activity of neighbouring cells.
This results in stimulated cells on the edge receiving less inhibition than cells in the middle (since
they have less neighbouring cells to inhibit them). This variation in stimulation allows edge
enhancement to occur, a crucial element which allows us to distinctly see an objects shape.
A lot of what we know today about the visual system and the brain comes from single-cell
recordings. This a process through which the pattern of electrical changes within a single
neurone is recorded. This procedure is frequently done with animals, by immobilising them and
placing electrodes outside of a neurone, their neuronal reaction to different visual stimuli can be
measured. This technique allows researchers to map out the cells’ receptive field, which is the
size and shape of the area in the visual world to which it responds.
One specific type of receptive fields are centre-surround cells, which have a different reaction
depending on whether the centre or the surrounding ring is stimulated. Similarly, egde detectors
are another type of cell, they however react to horizontal or vertical edges.
The visual system relies on many specialised cells in different locations to analyse incoming visual
information. Area V1, is the site on the occipital lobe where axons from the LGN first reach the
cortex. This area has all sorts of cells which respond to different visual stimuli. Another area,
called Area MT, is responsible for detecting movement (this area is damaged in patients with
akinetopsia) and Area V4 is responsible for detecting shapes. Many of these areas work
simultaneously by means of parallel processing. Within the optic nerve there are two types of
cells: (1) P cells, provide main input for LGN’s parvocellular cells, and are specialised in spatial
analysis and detailed analysis of form, (2) M cells, provide input for the LGN’s megnocellular
cells, and are specialised in the detection of motion and depth. These systems function at the
same time through parallel processing.
Some information from the occipital lobe is transmitted along the cortex to the temporal lobe
through the so called what system (major role in identification of visual objects). Simultaneously,
information from the occipital lobe is also transmitted to the parietal cortex through the where
system (major role guiding our action based on our perception of where the object is located).
Damage to the ‘what system’ results in visual agnosia, which is the inability to recognise objects.
Whereas damage to the ‘where system’ results in inability to reach for an object.
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, Clara Weber Cognitive Psychology 2019
Although the visual stimulus is processed by all different cells and systems, it comes together to
produce a smooth visual experience for us, which is known as the binding problem. There is still
debate about how exactly this occurs, however one contributor is spatial position. It is a major
organising theme within all brain areas concerned with vision. Another contributor is neural
synchrony, when neurones fire together it signals that they are both attributing a distinct feature
to the same object (e.g. movement or shape). A cause of neural synchrony is attention. For
example, when attention is overloaded we are likely to make conjunction errors, correctly
detecting visual features but incorrectly processing how they are bound together (someone seeing
a blue H and a red T might report seeing a blue T and a red H).
The Necker cube is an example of a reversible figure which can be perceived in different ways
(either as a cube viewed from above or from below). There are many similar stimuli, such as a
picture of a vase or two profiles facing each other. This is an example of a neutral figure/ground
organisation, meaning the is no clear background or depicted object, leaving two different
perceptions possible.
Perceptual constancy allows us to have a continuous understanding of the size, shape etc. of
objects, regardless of their setting. Specifically, size constancy refers to correctly perceiving
sizes of objects regardless of their position. We are better able to judge the size of an object if we
have a comparison object or setting. Helmholtz created the unconscious inference, which he
believed is a calculation our brain does when we perceive an object’s size. Two other constancies
are shape constancy (understanding it is the same shape despite having a different viewing
angle) and brightness constancy (objects have the same brightness despite being in dim or
strong light). There is a similar unconscious inference that occurs when we perceive brightness
and shape as well.
The perception of distance depends on various distance cues. One example of this is binocular
disparity, which is the difference between the view from both of our eyes. Binocular disparity
induces perception of depth even when no other cues are present. We are also able to perceive
depth with just one eye though monocular distance cues. Our eyes make small adjustments
according when viewing object and it these adjustments which indicate how far or close the
object is. Other monocular cues are frequently used by artists to create depth on a flat surface,
they are known as pictorial cues. When one object is blocking the view of another object (in your
line of vision) this is referred to as interposition. Furthermore, linear perspective is the way that
parallel lines seem to converge as they get farther away from the viewer.
Motion is another indicator of depth. When we move our head, the projection of the objects
closest to us moves more than those farther away from us, resulting in motion parallax. When we
move towards or away from an object the retinal stimulation changes, resulting in optic flow.
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