10 Most Common Cognitive Bias

Hello! Learning about human cognition is indeed fascinating. While humans like to believe that they are rational and logical, the fact is that on a daily basis people are continuously under the influence of cognitive biases, mental or psychological phenomena that distort thinking, sway beliefs or decision, and influence their decisions that lead to poor choices. Some of the most cognitive biases are given below. 

1. Confirmation Bias: the tendency to listen more often to information that confirms our existing beliefs. In other words, people tend to favor information that reinforces the things they already know or believe, refusing the opposing side. Some examples: following social media that you only like, choosing news sources that present stories that support your views, etc. Why is this happening? Perhaps it fuels the ego-centric satisfaction, it also protects self-esteem by making people feel that their beliefs are accurate. 
2. Hindsight Bias: the tendency to see events, even random ones, as more predictable than they are. Sometimes, it is also commonly referred to as the "I knew it all along" phenomenon. Some examples: you claim to know who will win the Election or World Cup, or what the exam answers are, after these events are just over. This bias occurs can be due to the tendency to view events as inevitable, and our tendency to believe we could have foreseen certain events. The effect of this bias is that it causes us to overestimate our ability to predict events. 
3. Anchoring Bias: the tendency to be overly influenced by the first piece of information that we hear or see, taking it as the final truth. Some examples: the first price produced during a price negotiation, or doctors can be susceptible to first impressions when diagnosing patients. Why does this bias occur? Perhaps the source of the information plays an influential role. Other factors such as priming and mood also appear to have an influence.
4. Misinformation Effect: the tendency for our memories to be heavily influenced by things that happened after the actual event itself. For example: a person who witnesses a car accident or crime could believe that their recollection is crystal clear. But studies have shown that simply asking questions emphasizing some keywords, or letting them watching a misguided video about an event can change someone's memories of what actually happened. This bias may occur because of interference, new information may get mixed with older memories.
5. Actor-observer Bias: The actor-observer bias is the tendency to attribute our actions to external influences and other people's actions to internal ones. When it comes to our own actions, we are often far too likely to attribute things to external influences. For example: You argued that the reason for missing an important meeting is because of a jet lag, or you failed an exam because the teacher posed too many trick questions. Conversely, however, when a colleague screwed up an important presentation we say it's because he’s lazy and incompetent (not because he also had a jet lag); when a friend failed a test, it happens because they lack diligence and intelligence (and not because they took the same test as you with all those trick questions). Our reasoning and perspective play a key role in forming this bias. 
6. False-Consensus Effect: the tendency people have to overestimate how much other people agree with their own beliefs, behaviors, attitudes, and values. For example: one may think that other people (friends and family members) share your opinion on controversial topics, or believing that the majority of people share your preferences. Why is this? We tend to generalize by thinking that the amount of times spent together make us easy to think the views of others conform with our own. This bias cause us to overvalue own opinions. It also means that we sometimes don't consider how other people might feel when making choices. 
7. Halo Effect: the tendency for an initial impression of a person to influence what we think of that person overall. It is also known as the "physical attractiveness stereotype". Some example: we may think that a good-looking and confident woman is also smarter, kinder, and funnier than less attractive people, or an attractive job applicant is seen as likable and more likely to be viewed as competent and qualified for the job. It is thought that this bias is due to our desire to be correct. If our initial impression of someone was positive, we want to look for proof that our assessment was accurate. It also helps people avoid experiencing cognitive dissonance, which involves holding contradictory beliefs. This bias is being used to advertise commercial products with attractive supermodels.
8. Self-Serving Bias: the tendency for people to give themselves credit for successes they make, but lay the blame for failures on outside causes. For example: when you do well on a project, you probably assume that it’s because you worked hard. But when things turn out badly, you are more likely to blame it on circumstances or bad luck. This bias is closely linked to self-esteem, age, and culture. 
9. Availability Heuristic: the tendency to estimate the probability of something happening based on how many examples readily come to mind. Some examples: after watching the news of car thefts in the neighborhood, you then start to believe that such crimes are more common than they are; or that plane crashes are more common than they really are because you can easily think of several examples. This bias is basically a mental shortcut designed to save us time when we are trying to determine risk, resulting in overthinking and worrying. 
10. Optimism Bias: the tendency to overestimate the likelihood that good things will happen to us while underestimating the probability that negative events will impact our lives. Some examples: we may assume we will get salary increment or bonuses, and that we won't be sacked in our current job; or we tend not to wear seatbelts because we feel the accident won't happen any time soon. Why is this bias? Because we may have over-confidence, or think that bad things often occur to other people and it seems more likely that others will be affected by such bad events.

Summary on Working Memory

Working memory is part of the cognitive domain called the executive function. The executive function is the mental processes that enable us to plan, focus attention, remember instructions, and juggle multiple tasks successfully. Scientists more or less agree that the triad of executive function is: working memory, flexibility, and inhibitory control.

Some important properties
The concepts of short-term memory (STM), or short-term store (STS), working memory (WM), etc. are fundamental to the field of cognitive science. The ideas date back to the time when George Miller, Brown, and Peterson & Peterson did various studies on selective attention during the ‘60s. For example, one has to remember a set of 3 alphabets. These sets are forgotten easily after 15 seconds when the person’s attention is diverted to another distracting stimulus. Hence, the concept of STM is closely related to selective attention and cognition in general.

In general, they are different from the so-called memory or the long-term memory in which the content has to be consciously recalled. William James mentioned that long-term memory has to be “brought back”, whereas STM is currently available. It is also related to conscious awareness. As a more special term, WM bears a connotation that it is a mental workbench where mental effort is applied. A popular example of WM is when you try to solve an arithmetic problem (4 + 30/2 = ?) or when you want to understand a foreign language. 

If STM is a type of memory, what is the capacity? It turns out that STM has a limited capacity. Miller originally proposed it has a magical container that can take up to 7 ± 2 items at once. Later research shows that a lesser capacity of around 4 ± 1 items at once is more acceptable (e.g. Cowan, 2010). Hence, STM is the bottleneck in our information processing system. Such capacity can be overcome by chunking or recoding strategy.

Related to the STM capacity is the term “forgetting” or losing the strength in the consciousness. In studies by Brown (1958) and a husband-wife Peterson & Peterson (1959), subjects were presented with a 3-letter (trigram) that did not make any linguistic sense (to prevent chunking), e.g. XMH. Afterward, subjects were given a number, say, 450. Then they had to count backward by three/four for a given interval, after which they have to recall what trigram they just saw. The performance is no better than chance after 3-4 seconds counting. A decay curve of “forgetting” can be fitted to predict the recall accuracy as a function of distractor interval. It seems that Brown-Peterson task points to the idea that WM storage decays as a function of time. However, Waugh and Norman (1965) proposed that it is the interference between the counting and the trigram that causes the forgetting, not time-dependent property per se. Indeed the number of interfering items in between the presentation of an item and the recall period contributes to the severity of forgetting. This temporal decay versus interference theory is still unresolved.

Once placed in the STM, how can the items be retrieved? Serial position curves reveal two properties of STM: the recency and primacy effect. In other words, an item held last or most recent in the queue and the earliest (deliberate attempt to rehearse, or put in the long-term storage) can be retrieved very accurately than the items in between (e.g. Glanzer et al.). A more developed model of STM retrieval comes from S. Sternberg (1969) which includes the way we search a desired item in the STM container, brings an item of interest to consciousness, and do an appropriate response. He was interested in whether people scan items in the short-term memory one at a time (serial processing) or all at once (parallel processing). 

In one study, Sternberg presented a display of numbers from 1 to 6 different digits to subjects. These items are so-called the memory set. Then he showed the subjects a test digit and they had to decide whether the test digit had been included in the display just shown. If parallel processing occurred, the length of the presentation should not influence the reaction time, but if serial processing occurred, the reaction time should increase as a function of presentation time. An interesting finding was that the reaction time was about the same whether the response was a "yes" or a "no." In other words, participants did not stop responding when they found a match but continued searching the entire display in their memory. This process is called an exhaustive search. Thus, Sternberg concluded that people perform an exhaustive search when retrieving information from STM. 

Distinct Components of WM
In the 60's, Atkinson and Shiffrin talked about STM model. The more elaborate model, originally proposed by Baddeley and Hitch (1974), was based on Shallice & Warrington's and other clinical cases. According to Baddeley's model, WM by no means has a central controller and two different components or "slaves" that work independently.
1)  Phonological loop: maintains, manipulates acoustical, verbal information, e.g. rehearsing words. 
2)  Visuospatial sketchpad: maintains, manipulates visual and spatial information, e.g. playing chess.
3)  Central executive: acts as a manager that controls and oversees the use of different WMs.
4)  A more recent development is a component called episodic buffer. 

Phonological loop is related to observed phenomena e.g. phonological similarity, articulatory suppression, and clinical studies of aphasic patients with dyspraxia. The primary goals of the central executive controller is binding information from a number of sources into coherent episodes, coordination of the 3 components, shifting between tasks/retrieval strategies, and selective attention & inhibition. The prefrontal cortex is important for such purposes.

The visuospatial sketchpad has also been expanded quite recently. For e.g., Logie expanded the Baddeley's visuospatial sketchpad by dividing the system into optical (visual) and spatial (mental imagery, movement information). Smyth et al. (1988) shows how subjects performed a recall of a series of movement sequence and this is thought to involve the visuospatial sketchpad. Other studies have shown that there is less interference between visual and spatial tasks than between two visual tasks or two spatial tasks. This suggests that the two entities may be more independent than initially thought.

There are tons of neuropsychological test batteries to investigate WM in humans and patients. Digit span test, where a person is presented with a series of digits one after the other and has to repeat the digits in the same order, is arguably the most common test to access verbal working memory. A variant of this, alphabets, may be used. Corsi Block Test is the spatial equivalent of the test that taps into the spatial working memory. Mental rotation test is another visuospatial test that may also involved mental imagery. Because of the online nature and the link between WM, cognition, and problem solving, WM is sometimes thought to describe some kind of intelligence.

Neural Substrates of WM
The dorsolateral prefrontal cortex (DLPFC), equivalent to BA 9 and BA 46, (or Area 9/46, Petrides & Pandya in primates), is thought to be the most important part for WM both in humans and monkeys. Much of the earlier works in non-human primates were done by Goldman-Rakic in the '80-'90s using a paradigm called delayed-response task. She found that lesion to DLPFC impaired the task performance. A series of neuroimaging studies have corroborated this finding, confirming the involvement of DLPFC in working memory tasks. According to d'Esposito and colleagues, there is a lateralization of functions, in the sense, verbal working memory is more left-lateralized versus visuospatial which is right-lateralized.

From Neuroanatomy to Cognition

White Matter Fibres
The white matter was briefly mentioned in an earlier post, so this is sort of a continuation of the brain's gross anatomy. The white matter is located underneath the cortical gray matter and composed of fatty myelinated axons. It is an integral part of the central nervous system that transmits messages very rapidly. It basically has 3 types of fiber bundles: the projection fibers, commissural fibers, and association fibers.

1. Projection fibers are bi-directional, afferent, and efferent bundles. They appear as radiating bundles in the white matter that exit the cerebral cortex and converge towards the brainstem. One bundle carries visual information through the optic radiation. Near the subcortical nuclei, these axons form a compact band known as the internal capsule with anterior and posterior limbs. Afferent (sensory) fibers: mainly the thalamocortical bundles going to the various region of the cerebral cortex. The efferent fibers of the internal capsule arise from the cerebral cortex. They form various tracts, e.g. corticothalamic, corticobulbar, corticospinal, and corticopontine bundles. 
2. The axons part of the corpus callosum forms the commissural fibers. At different callosal segment, they have different connections: the rostrum (orbitofrontal), genu (frontal lobe), body (sensorimotor and posterior parietal), and splenium (posterior temporal and occipital). Other commissural fibers are the anterior commissure, connecting the olfactory system bilaterally.
3. The association fibers form the bi-directional cortico-cortical bridges connecting areas within the same hemisphere. They can be classified as short and long fasciculus:
        - Superior longitudinal fasciculus connects frontal and parietal lobes.
        - Occipito-frontal fasciculus connects frontal and occipital lobes.
        - Arcuate fasciculus connects the frontal with posterior temporal lobes.
        - Uncinate fasciculus connects orbitofrontal with anterior temporal lobes.
        - Inferior longitudinal fasciculus connects temporal and occipital lobes.
        - Extreme capsule fasciculus connects lateral temporal and lateral frontal lobes.

Of interest is the coronal section of the cerebral hemisphere from the insula moving inwards to the thalamus. The external capsule connects the motor cortex to the putamen and is unidirectional. The internal capsule connects specific thalamic nuclei to the specific cortical area and hence it is bidirectional.

The most common way to study the white matter is through MRI which can be observed well on T1-weighted, T2-weighted, and FLAIR sequences. More recently, scientists become more interested in modeling brain development over puberty and brain decline associated with aging. Fun facts: Gray matter volume increases in early childhood but declines after puberty. However, white matter volume progressively increases over time, supporting the concept of neural plasticity.

Cerebral organization
The cerebral cortex is organized into six layers that arise from the time of its development. This is the characteristic of the neocortex. Only the piriform cortex and the hippocampal formation, the oldest cortical structures phylogenetically or paleocortex or allocortex, do not exhibit this six-layer arrangement. The projection fibers are more deep-rooted, while the association and commissural fibers are more superficial. Three principal types of cells found in the cortex include the pyramidal, stellate, and fusiform neurons. Their fibers are arranged either tangentially or radially across layers.

Pyramidal cells, with a shape of a triangle with the top end going up to the surface (apical) and the horizontally running dendrites (basal), constitute the most in various cortical layers. The axons are either going down to the white matter (as projection fibers) or to other cortical areas (as association fibers). The biggest pyramidal cell, the Betz cell, is found only in Layer V of the precentral gyrus or motor cortex. Unlike pyramidal cells, granule or stellate cells are small, polygonal or triangular in shape. They are found in all layers, but especially numerous in Layer IV. Fusiform neurons are spindle-like cells found mostly in the deepest cortical layer, their long axis going vertically upward. Apart from these three types of cells, we encounter others, e.g. horizontal cells found mostly in the superficial layers. The works of Cajal and Golgi are crucial in deepening our understanding on these cells.

Fig-1: Six different cortical layers of the cerebral cortex, layer-I being the most superficial.

In brief, six-layered architecture can be described as follow:
a). Layer I (molecular layer), has few cell bodies, mostly axons, Layer II (external granular layer).
b). Layer III (external pyramidal layer), cells forming mainly association or commissural fibers.
c). Layer IV (internal granular layer), mainly the incoming afferent fibers from the thalamus.
d). Layer V (internal pyramidal layer), mainly efferent projection fibers.
e). Layer VI (multiform, fusiform layer).

What is the relationship between this architecture with the earlier functional lobes? Layer III plays a major role in cortico-cortical connections. Layer IV is predominant in sensory areas in the parietal and temporal lobes, e.g. the postcentral gyrus. These regions are granular. Layer V, on the other hand, is predominant in motor areas, e.g. precentral gyrus.

Fig-2: The distribution of different cortical composition: (1) Agranular; (2) Granular - frontal (dysgranular); (3) Granular - parietal; (4) Granular - occipital; and (5) Koniocortex. Only cortical motor areas are agranular.

Principal neurotransmitters

A variety of neurotransmitters is associated with neurons of the cerebral cortex. Among those, we have glutamate, aspartate, and γ-aminobutyric acid (GABA). Pyramidal cells are the main efferent neurons that are predominantly glutaminergic and are excitatory. Most interneurons within the cortex, however, are GABAergic and are inhibitory. They are bridging the afferent and efferent fibers together. Therefore the outputs of the cortex are modulated by a variety of cortical afferents via interneurons. 

A variety of neuropeptides or monoamines are also found in the cerebral cortex; they influence not only populations of neurons but also local metabolic activity and vascular smooth muscle. The most important monoamines in the cortex are (1) norepinephrine, which originates from the locus ceruleus of the pons and distributes sparsely to all cortical layers; (2) dopamine, which arises from the substantia nigra–pars compacta and the adjacent ventral tegmental area and is found in moderate amounts in layers I and VI and sparsely in layers II to V; and (3) serotonin, which arises from the raphe nuclei and distributes heavily to all cortical layers.

Cognition and the Brain
The study of human cognition and the brain is the heart of a classic science popularly known as neuropsychology. The interests existed since the time of Descartes, Gall, Broca, and so on, who studied the link between a neurological condition (e.g. lesions) and certain behavioral or psychological processes. A classic theory, phrenology, says that the brain is divided into discrete and unique areas responsible for a particular function only. The mastery of certain skills can be deduced by the bigger skeletal landmark of the head. An opposing view at that time held that there is no localization of brain functions and that the functions (what they called "Mind") are distributed across different parts of the brain. With more discoveries, modern neuroscience later thought that the brain is divided into many functional specialization. For example, one may use fMRI to elucidate brain areas associated with some behavioural tasks. One fundamental characteristic of the central nervous system is parallelism, that is, a large number of functions are simultaneously processed along two or more pathways. As a result, the damage of one pathway can allow other pathway to function, and that one brain function can be performed not only strictly by one area. 

Modern neuropsychology enjoys a multidisciplinary collaboration among cognitive scientists, physiologists, neuroscientists, and clinical psychologists. Originally, the field drew strong attention when Paul Broca came into contact with a patient undergoing a progressive speech disorder in 1861, who could only produce "tan". After the patient died, Broca found out that his inferior frontal gyrus (IFG) was damaged. Named after Broca, the type of such behavioral deficit linked to the damage of IFG is then called Broca's aphasia. Note: IFG is rostral to the mouth/orofacial musculature of the cortical motor area.

Fig-3: The difference between Broca's and Wernicke's aphasia together with affected areas on the left hemisphere.

Broca's finding was further developed with the findings of Carl Wernicke. He found that in a certain type of language disorder, the patients were able to produce speech but unable to comprehend the conversation. Called Wernicke's aphasia, the damage is found to be around the posterior part of the superior temporal gyrus (STG). This aphasia is not equal to deafness, for the person with Wernicke's aphasia is able to detect sound but unable to make sense of it. He further hypothesized that there is a link between IFG and STG and this is crucial in language. To be able to converse well, one has to first listen and understand the sentences one hears. Note: STG is near to the primary and secondary auditory cortex.

In the 1870s, John Hughlings Jackson proposed that the cerebral cortex is organized hierarchically and that some cortical areas are for higher-order functions (or cognitive) that are neither fully sensory nor motor. These brain areas are called association areas because they serve to associate sensory inputs to motor response and conduct mental processes related to sensorimotor behavior. The mental processes that Jackson attributed to these areas include interpretation of sensory information, the association of perceptions with previous experience, focusing of attention, and exploration of the environment. Jackson's finding is supported by clinical works. The major helps come from surgical rooms of patients with damage or lesion on the specific are, or people with underlying conditions. Other methods include experimental studies with monkeys and rats and the use of non-invasive brain imaging technology.

Before ending, I wish to mention major associative areas in the human brain important in cognition:

1. The posterior association area: the margin of the parietal, temporal, and occipital lobes. It integrates information from several sensory modalities such as vision, space, and body senses. It is also involved in language. Separate studies by Holmes and Luria on wounded soldiers found that bilateral injuries to the posterolateral parietal lobe yield to normal visual acuity but the soldiers were unable to scan visually or reach for an object of interest. They could not process together with the visual information when asked to describe in words what that they saw. This shows that the region is critical for integrating different sensory modalities and for using that integrated information to direct behavior. 
2. The anterior association area: the prefrontal region, rostral to postcentral gyrus. It is involved in the planning of action, shaping behavior, and judgment; a more popular term is the "Executive function". The most popular case showing how the injured prefrontal region leads to behavioral problems is perhaps of Phineas Gage. A series of clinical tests, e.g. the Tower of London test and the Wisconsin Card Sorting Test (WCST), can be used to diagnose people with neuropsychological disorders who have lost their executive functions, such as schizophrenia. WCST is primarily considered a test of executive functions, particularly abstract reasoning and cognitive flexibility in response to external changes.
3. The limbic association area: along the lower medial end of the cerebral hemisphere. It is for emotion, learning, and memory. Its involvement in learning and memory comes from the well-known study on patient H.M. by B. Milner in 1960s after both medial temporal lobes had been removed. She first demonstrated the remarkably selective role of this part of the brain in converting short-term into long-term memory. Studies in monkeys have helped establish that association areas in the medial temporal lobe, including the hippocampal formation, receive information from virtually every other association area. In other words, the hippocampal formation is able to sample the whole stream of ongoing cognitive activity and thereby relate different aspects of a single event so that they can be recalled as a coherent experience.

More recently, cognitive neuroscience is recognized as another separate field, combining neuroscience, neurophysiology, and psychology. Scientists now agree that the three areas (the triad) of executive function are working memory, flexible thinking, and inhibitory control.