Intelligence Testing

Intelligence testing refers to the application of standardized tests in attempt to measure and assess intelligence. The first mental testing may have been performed in China in the form of the imperial examination system, and modern intelligence testing commenced in France in the 19th century as a means of separating mental retardation from mental illness (1). The French psychologists Alfred Binet, Victor Henri, and Theodore Simo, published the Binet-Simon test in 1905. This test was focused on verbal abilities and was meant to identify mental retardation in school children. The score on the test would then be termed the child’s mental age. The American psychologist Henry Goddard translated Binet’s work in 1910, and it was used by the Eugenics movement to give them credibility in diagnosing mental retardation, resulting in thousands of women being forcibly sterilized based on their test scores (2).

Intelligence Testing focuses on any of a number of cognitive abilities, including:

Spatial imaging
General knowledge

Well-known modern IQ tests include Raven’s Progressive Matrices, Wechsler Intelligence scale for children, Wechsler adult intelligence scale, woodcock-Johnson sets of cognitive abilities, Stanford-binet, and the Kaufman assessment battery for children.


(1) Kaufman, Alan S. (2009). “IQ Testing 101“. New York, NY: Springer Pub. Co., Print.

(2) Larson, Edward J. (1995). “Sex, Race, and Science: Eugenics in the Deep South“. Baltimore: Johns Hopkins University Press, Print.

Word Superiority Effect

The word superiority effect (WSE) refers to the phenomenon that people can easier recognize letters presented within words as compared to isolated letters and to letters presented within nonword (orthographically illegal, unpronounceable letter array) strings. The effect was first described by Cattell (1886), and important contributions came from Reicher (1969) and Wheeler (1970).


Chase, C. H. and Tallal, P.: 1990, ‘A developmental, interactive activation model of the word superiority effect’, Journal of Experimental Child Psychology 49, 448-487

Gestalt Psychology Principles

Gestalt psychology is an approach to studying the mind and brain operating on the principle that the brain is holistic, parallel and analog, with self-organizing tendencies.

Gestalt psychology principles are:

Figure-ground principle, which describes the process of identifying a figure from the background.

Proximity, which describes the idea that if objects are close together we tend to group them together.

Similarity, which describes the tendency of the brain to group together objects that are alike.

The principle of closure explains how sometimes we see a complete image even if it’s incomplete.

The principle of continuity explains how the brain prefers to see a continuous motion as opposed to a series of smaller parts.

Split Brain Experiments

In some severe cases of epilepsy, patients have undergone a callosotomy, which is a procedure where the corpus collosum (a set of nerve fibres connecting the two cerebral hemispheres) is severed. This has proven successful in controlling severe seizures (1). Tests carried out on these ‘split-brain’ patients have yielded some interesting results. In the 1960s, Michael Gazzaniga and Roger Sperry designed tests for investigating how the separation of the hemispheres had effected the mental capacities of the patients. When presenting visual or tactile information to the right visual field (left hemisphere) of the patients (who, as most people, had a left-brain dominance for language processing), they were able to verbalise and write what they saw or felt. When the same information was presented to the left visual field (right hemisphere), they were unable to elicit the same verbal and written responses. Despite not having the same verbal capacities, when the patients were asked to give non-verbal responses to the visual and tactile information presented to the right hemisphere, they were able to do so. For example, when an object such as a cigarette was presented, the split-brain patients were able to match it to an image of an ashtray, when given several images to choose from. Based on these types of tests, researchers have concluded that, despite there being sub-cortical connections between the two hemispheres, some aspects of mental functioning work independently within each hemisphere (2).

1. Gazzaniga, M. S. (2005). “Forty-five years of split-brain research and still going strong“. [Review]. Nature Reviews Neuroscience, 6(8), 653-U651.

2. Gazzaniga, M. S. (1967) “The split brain in man“. Sci. Am.217, 24–29.

Craik and Lockhart Levels of Processing Framework

The levels of processing framework proposed by Fergus I.M. Craig and Robert S. Lockhart in 1972, refers to three levels of encoding any information: visual encoding (concerned with visual stimuli), phonemic encoding (concerned with visual and auditory stimuli) and semantic encoding (concerned with meaning). Shallow processing, (visual and phonemic processing), leads to a fragile memory trace that is susceptible to rapid decay, and deep processing (semantic processing) results in a more durable memory trace.

Baddely and Hitch Model of Working Memory

The Baddely and Hitch model of working memory is composed of four components:

- The central executive, which acts as supervisory system and controls the flow of information to and from its slave systems.

- The phonological loop, which deals with sound or phonological information; any auditory verbal information is assumed to enter automatically into the phonological store.

- The visuo-spatial sketchpad, which holds information about what we see; it is used in the temporary storage and manipulation of spatial and visual information, such as remembering shapes and colors, or the location of objects in space. It is also involved in tasks which involve planning of spatial movements, such as planning one’s way through a complex building

- The episodic buffer, which is a third slave system, and is dedicated to linking information across domains to form integrated units of visual, spatial, and verbal information with time sequencing or chronological ordering, such as the memory of a story or a movie scene.

Context-dependent Cues

Context dependent cues are environmental cues which aid in accessing the memories formed in a certain context. It has been demonstrated that the recall of specific episodes and information improves when the context present at encoding and retrieval are the same.

Sensory Memory

Sensory memory is a form of memory that lies within the sensory apparatus, and has separate hypothesized registers for the different sense modalities. Iconic memory receives all the visual information and echoic memory receives all the audio information. Only the information we pay attention to is maintained and passed to the short-term memory.

Atkinson and Shiffrin Modal Model of Human Memory

According to the Atkinson and Shiffrin modal model, memory is structured into three stores: sensory memory (a short duration store that encodes mainly visual and auditory information), short-term memory (consists of the information that is stored up to 30 seconds) and long-term memory (information that is stored for longer than 30 seconds). The information passes between the stores in a linear way and is passed from short-term memory to long-term memory through repetition.

Dual Code Theory

According to dual code theory, hypothesized by Allan Paivio in 1971, people perceive verbal and nonverbal stimuli through their sensory systems (eyes and ears). From here the information is passed into the verbal and nonverbal associative systems, that work independently or together to produce verbal and nonverbal responses.

Implicit and Explicit Memory

Implicit memory is a type of memory in which previous experiences aid in the performance of a task without conscious awareness of these previous experiences. This allows people to remember how to tie their shoes or ride a bicycle without consciously thinking about these activities. Explicit memory is the conscious, intentional recollection of previous experiences and information. People use explicit memory throughout the day, such as remembering the time of an appointment or recollecting an event from years ago.

Person Perception

Person perception refers to the impressions people form about the people around them, using subjective processes such as the effects of physical appearance, social schemas, stereotypes, illusory correlations, the spotlight effect and discrimination (in-groups/out-groups).

Depth Perception

Depth perception is the visual ability to perceive the world in three dimensions, enabling judgments of distance. Depth perception arises from a variety of depth cues, which are typically classified into monocular and binocular cues.

Monocular cues can provide depth information when viewing a scene with one eye, and include:

- Motion parallax: This effect can be seen clearly when driving in a car. Nearby things pass quickly, while far off objects appear stationary.

- Perspective: An example would be standing on a straight road, looking down the road, and noticing the road narrows as it goes off in the distance.

- Aerial perspective: Images seem blurryer the farther away they are.

- Overlap or interposition: If one object partially blocks the view of another object, it is percieved as being closer.

- Texture gradient: The texture of an object can be seen clearly when closeby, but becomes less and less apparent the farther away the object is.

Binocular cues provide depth information when viewing a scene with both eyes, and include:

- Stereopsis or retinal disparity: By using two images of the same scene obtained from slightly different angles (right and left eyes), the brain can calculate depth in the visual scene providing a major means of depth perception.

- Convergence: This is the simultaneous inward movement of both eyes toward each other when viewing an object, stretching the eye muscles and helping in depth/distance perception.

Schedules of Reinforcement

Schedules of reinforcement are modes of systematically sequencing positive and negative reinforcement. There are four types of schedules: fixed ratio, variable ratio, fixed interval and variable interval. Ratio refers to the number of behaviors needed before achieving a positive or negative reinforcement. Interval refers to the time between reinforcements.