Theoretical psychology

week 4

problem with early psychological tests for intelligence

not based on scientific insight into the underlying mental abilities → unclear what intelligence was

Dissemination of genes

* our genetic ancestors lived in Africa some 180.000 - 200.000 years ago
* human genome contains over 30.000 - 35.000 genes, which determine many of our mental abilities, including our intelligence

Francis Galton

* studied twins for nature vs. nurture debate
* in line with Locke: assumed that our general intellectual power is linked to our ability to make sensory discrimination
* developed the correlation coefficient to quantify the relationship between variables
* invented a machine to demonstrate normal distribution
* developed standard deviation to quantify normal variation

James Cattell

* created mental tests for measuring elementary psychological abilities, e.g., reaction time to sounds, naming colours, judgement of 10 second time, and bisection of a 50 cm line

→ test scores did not correlate with one another & correlation between test scores and exam grade of students was around 0

* Spearman: argued that cattell would have found positive correlations if he would have sampled from a more varied population (not just Columbia students) and applied correction for measurement errors

Alfred Binet

* change in french education during end of 19th century: mandatory for children aged 6-14 to attend school

→ French government asked Binet to develop a test that could separate normal children from those with learning difficulties and to measure the differences

* Binet’s test could identify children with special needs, but without guidance of a theory of intelligence

→ later: Stanford-Binet Test

Stern

* 1912: proposed the concept of IQ (child’s score on intelligence test/child’s chronological age)

Spearman

* successfully measured intelligence: computed correlations between school children’s grades for classics, French, English, mathematics, & music and tests of sensory discrimination abilities for light, pitch, and weight

→ all correlations were positive → general intelligence factor (g) that underlies the performance on all tests

* High g → good performance on all tests
* each test also involves a specific ability (s) for mathematics/language/sensory discrimination/music
* two factor theory of intelligence: s and g determine intelligence

Wechsler

* Wechsler Adult Intelligence Scale (WAIS): improvement of the Stanford-Binet Test, including an IQ distribution
* among the most widely used tests today
* measures crystallised and fluid intelligence
* IQ scores follow a normal distribution with mean = 100 and sd = 15

John Raven

* Progressive Matrices Test: 3\*3 Matrix with bottom right cell missing and task is to determine regularities in the other cells and then select the missing cell form among 8 alternatives

→ measures fluid intelligence

Raymond Castell

* Culture Fair Intelligence Test: aims to measure g devoid of cultural influences
* divided g into 2 subtypes:

1) fluid intelligence: ability to solve new problems with no assumption of prior knowledge; declines with age; performance IQ

2) crystallised intelligence: ability to use acquired declarative knowledge, such as vocabulary and knowledge of facts; improves with age; verbal IQ; product of fluid intelligence x educational & cultural experience

Flynn effect

* test scores on WAIS (intelligence scores) increased almost linearly during the past century

Darwin’s variability hypothesis

* variability hypothesis: in humans and many other species males display greater variation in physical characteristics than females
* Thorndike - extension: men are more likely than women to have either very high or very low intelligence
* Hollingworth: tested hypothesis by examining thousands of case records of every low intelligence patient at the clearing house for mental defectives in NY

→ more men than women with low intelligence recorded, but this ratio decreased with age

→ possible explanation: men were faced with greater societal expectations than women, thus deficiencies were often detected at an earlier age in men than in women → overrepresentation of men in the database of low intelligence individuals

Helen Thompson

* had groups of male and female students perform a battery of tests of sensory, motor, and intellectual functions

→ found more similarities than differences, so women were not mentally inferior to men

Kurt Lewin

* founder of social psychology: put emphasis on both the person and the environment (the momentary social situation)
* Central idea: B = f (P,E)

→ B = Behavior

→ f (P,E) = function of personal characteristics (P) and environmental factors of the group (E)

* force field analysis: examine forces that influence a (social) situation, consisting of helping and hindering forces toward a goal
* social action research: psychological research should be used to make societies better

Charlotte Bühler

* focused on the influence of other family members

Gestalt theory

* = the whole is different from the sum of its parts
* guided research on problem solving behavior in Europe
* aim: understand how intelligence works

Wolfgang Köhler

* studied chimpanzee’s problem solving: chimps stacked wooden crates to create a ladder to retrieve food form a ceiling in the cage & combined sticks together to lengthen the reach of their arms

→ suggestion: chimps arrived at these solutions by seeing how the parts (wooden crates) should be combined into a whole (ladder) to reach a goal (bananas)

→ chimps solve problems through insight rather than trial-and-error, as American behaviourists assumed

Max Wertheimer

* productive vs. reproductive thinking

→ productive thinking: solving a problem with insight (similar to fluid intelligence)

→ reproductive thinking: solving a problem by retrieving previous knowledge (similar to crystallised intelligence)

Frederic Bartlett

* experiment: English subjects had to remember a Canadian Indian story which had a plot developing in a way that was strange to European culture

→ subjects changed story in more familiar forms as they tried to remember it

* remembering = reconstructive process in which information is retrieved and changed to fit into existing cultural schemata
* In contrast to Ebbinghaus asked for the recall of MEANINGFUL stories, assuming that recall was the reconstruction of memory traces under the guidance of schemata rather than the retrieval of associations in memory

→ both studied episodic memory

Naom Chomsky

* argued that children learn their first language without being explicitly taught
* against skinner: operant conditioning principles cannot explain why humans speak and understand sentences they have never heard before
* proposed that humans have an innate language acquisition device, explaining why a first language is acquired so quickly

Roger Brown

* first experimental studies on children’s language acquisition
* tip of the tongue phenomenon: feeling of knowing a word (often a person’s name) that can only be partly retrieved from memory

→ shows that even remembering words is a reconstructive process

* flashbulb memories: concern highly detailed memories of what people were doing at the time they heard about major traumatic events

→ one account: amygdala is activated by the emotion and facilitates consolidation of the memory by activating the connected hippocampus

George Miller

* revival of Wundt’s attention span
* found that attention span is about 7 +/- 2

→ capacity of attention span can be increased by recoding the elements, e.g., reorganise T,H,E,O,E,S,R,E,U into “TREEHOUSE”

Donald Broadbent

* revival of Wundt and James’ selectivity of attention
* filter mode, formalised with a flow chart

→ flow chart: specifies a sequence of processing stages

→ When we are asked to report the right-ear word, and then are exposed to one word in the left and one in the right ear, a filter blocks further processing of the left-ear word, so that we can identify and report the right-ear word

→ so: conscious identification requires attention

Jerome Bruner

* revival of introspection method (Külpe) by having subjects introspectively report on how they were performing stimulus categorisation tasks

Herbert Simon

* Rediscovery of Selz: procedural knowledge (if-then rules) underlies problem solving

→ evidence: computer programs using if-then rules could solve problems, such as the Tower of Hanoi

* serial rule application is also involved in solving the raven progressive matrices test

→ supports the view that intelligence is the ability to solve problems through the serial application of if-then rules

* Simon + Alan Newell: founders of Artificial Intelligence (AI)

→ in 1997 the chess programme of IBM defeated the world champion through a combination of fluid intelligence (brute force thinking, general if-then rules) and crystallised intelligence (extensive record of previous games & if-then rules in memory)

→ Metaphor: the human brain is an organ that processes information

Wundt - g factor

* assumed that the g factor reflects someone’s apperception/attention capability (attentive processing involving relating, comparing, synthesis, or analysis linked to frontal lobes)

Spearman - g factor

* g reflects someone’s quantity of mental energy

Thomson - g factor

* g does not reflect a single psychological mechanism
* sampling theory: the test scores positively correlated because of overlap between the multiple mechanisms engaged by the tests, e.g., classics, English, and French tests all require the ability to process letters

John Duncan

* attention and intelligence are both linked to frontal lobes

→ challenges sampling theory, which predicts multiple brain regions should be engaged in intelligence
* PET imaging study: students performed a Raven-like task in PET scanner; on each trial they had to indicate by pressing one of four buttons which of four spatial figures or letter sequences was the odd one in the series

→ items were difficult (high g) or easy (low g)

→ subtracting low g from high g PET images revealed activity in frontal cortex in both the spatial and verbal conditions, suggesting g is linked to solely the frontal cortex

* later research revealed that g is linked to frontal and parietal cortex

COMT genotype, dopamine & intelligence

* COMT gene codes for COMT enzyme which breaks down dopamine in frontal and parietal cortex

→ Alleles for COMT genes are Val or Met, one is received from the father, one from the mother; possible combinations: ValVal, ValMet, MetMet

→ Val allele codes for the version of the COMT enzyme that works harder than that of the Met allele, so dopamine remains longer in frontal and parietal cortex and eases performance of intelligence-requiring tasks

→ higher activity in frontal parietal network during intelligence-requiring tasks for people with the ValVal genotype, than for people with the ValMet or MetMet genotype

Sternberg vs. Duncan

* Sternberg: a link between intelligence and frontoparietal cortex activity does not imply that the relation is a causal one

→ Duncan et al. observed that damage to frontoparietal cortex reduces fluid intelligence, whereas temporal cortex damage does not → causal link

* Duncan: solving Raven-type problems involves working serially from one subgoal to another each with focused attention until the overall goal is achieved

Fluid intelligence and frontal cortex lesions

* brain damage depends on the amount of damage espressed in cubic centimeters
* damage to frontal cortex reduces fluid intelligence
* damage to temporal cortex does not reduce fluid intelligence