Introduction to Psychology

Psychology

Is a scientific study of mind and brain with the purpose of explaining behaviour

DNA molecule

Located in the nucleus, the control center of the cell, it is organized into 46 chromosomes (23 pairs); contains the complete genetic instructions for an individual's development and functioning.

Genes

Meaningful sections of a DNA molecule, that govern the cells’ functioning by providing instructions for making proteins

• each gene is paired with another gene; the pairs are located at corresponding positions on pairs of chromosomes.

Gene expression

Whether a gene is turned “on” or “off”; the extent to which a gene is transcribed into a sequence of amino acids (protein)

Methylation

An epigenetic process where chemical tags called “methyl groups” are added to a gene's DNA, which can act like a switch to turn the gene "on" or "off" without changing the DNA sequence itself.

It is determined by the biochemical environment.

Genotype

An organism’s specific set of genes

Phenotype

The overt traits and behaviours of an organism.

• phenotype is determined by genes x environment

Allele

A distinct version or alternative form of a gene. For any given gene, an individual inherits two alleles, one from each parent; they can be either dominant or recessive

Polygenic inheritance

When one character is affected by multiple alleles (e.g. eye color)

Natural selection (3 conditions)

• there is variation among individuals of a population

• individuals with certain traits survive at a higher rate

• the trait associated with this advantage is inheritable

=> specific traits will be better represented in the next generation; what matters is the survival of genes, NOT of individuals.

! It does NOT follow that evolution “improves” organisms or can only lead to rigid behavioural patterns

Heritability

a statistical measure that estimates the degree to which genetic variation accounts for differences in a specific phenotypic trait. It's represented as a proportion, ranging from 0 to 1

Evidence that supports modern evolutionary theory

• the finding of fossils

• the resemblance between genomes of various organisms

• the finding of pseudogenes

• distribution of species across the world (e.g. continental vs. oceanic island)

The makeup of the nervous system

• glia - a type of cell that provides physical and chemical support to neurons and maintains their environment; they are sometimes called the "glue" of the nervous system

• neurons - cells of the brain and nervous system that transmit information using electrical and chemical signals

  • sensory (afferent) neurons - carry information from sensory receptors (like in the skin, eyes, and nose) to the brain

  • motor (efferent) neurons - send commands from the central nervous system to muscles and glands.

  • interneurons - connect sensory and motor neurons, relaying information between them; the most common in the brain

Synapse

A place where a signal passes from one nervous cells to another 

(pre-synaptic neuron → synapse → post-synaptic neuron)

The firing of neurons

Neurons either fire or do not (all-or-none law)

• intensity variations by

  • the number of neurons firing

  • firing rate

Neurotransmitter

A chemical substance that transmits signals between neurons

→ (lock and key model)

• effect of neurotransmitters is terminated by autoreceptors, synaptic reuptake and enzymes

• the binding of a neurotransmitter with a receptor produces an excitatory or inhibitory signal

Agonists & Antagonists

Phrenology

a discredited pseudoscience from the 19th century that claimed the bumps and contours of a person's skull could reveal their mental faculties and character traits.

Methods of studying the brain

• clinical observation of patients with brain damage

• experimental techniques

  • transcranial magnetic stimulation (TMS)

  • invasive: animal studies

• other techniques

  • electrophysiology: EEG, ERP

  • brain imaging: (f)MRI, PET scan

Consciousness

One’s subjective experience of the world, resulting from the brain activity.

Fundamental assumptions:

• brain and mind are inseparable

• each of us experiences consciousness personally; we cannot know that everyone feels the world the same way

• consciousness arises as a function of which all brain circuits are active → global workspace model

After-the-fact explanations

Creating the illusion that one’s behaviour was intentional when it wasn’t

Attention

A process that enables you to focus selectively on some things and avoid focusing on others

• for instance, cocktail party phenomenon (Cherry, 1953)

BUT! sometimes the unattended message breaks through (e.g. one’s name)

Change blindness

When you are not attending to something, you are mostly unaware of the change occurring in that area/object

Restorative sleep theory

Sleep is needed to maintain / repair the body

Circadian rhythm sleep theory

Sleep is needed to keep mammals quiet during the most dangerous part of the day (at night)

Facilitation of learning theory

Sleep strengthens neural connections

Dreams

Products of an altered state of consciousness in which images and fantasies are confused with reality

Addiction

Drug use that remains compulsive despite negative consequences; physical & psychological dependence

Drug tolerance

Increasing amounts of a drug needed to achieve the same effect as previously

Stimulants

Drugs that increase behavioural and mental activity and activate the sympathetic nervous system (e.g. cocaine, nicotine, caffeine, amphetamine)

Depressants

Drugs that reduce behavioural and mental activity by depressing the central nervous system (e.g. alcohol, benzodiazepines, barbiturates)

Opiods

a.k.a. narcotics, depress / slow down the central nervous system + relive pain (e.g. heroin, morphine)

Hallucinogens

a.k.a psychedelics, produce alterations in cognition, mood and perception (e.g. LSD, psilocybin mushrooms)

Sensation

The detection of an external stimulus & the transmission of this information to the brain

Perception

The processing, organisation & interpretation of sensory signals

Distal stimulus → Proximal stimulus → Transduction → Sensation → Perception

The senses

• Vision

• Hearing

• Taste

• Smell

• Skin senses

• Vestibular sense

• Kinesthesis - movement in the space

Quantitative variation (intensity)

• rates of neuron firing

• total number of neuron firing

Qualitative variations (sensory quality)

• different sensory qualities are signaled by different neurons

• certain sensory qualities arise because of different patterns of activation across a whole set of neurons

Adaptation

The tendency to respond less to stimuli that have been present and unchanging for some time

Light

The main stimulus for vision; light can vary in intensity and wavelength, and is absorbed by pigments in the receptors

Rods & cones

• rods are responsible for night vision

• cones are responsible for day vision 

=> distribution of rods and cones across the retina results in the higher resolution in the fovea

Opponent-process theory (Hering)

• existence of “after-images”

• there is no such thing as “blue-yellow” or “red-green”

=> three opponent processes: black-white, red-green, blue-yellow

Trichromatic theory (Young-Helmholz)

Suggested that there are three receptors for color vision: blue, green and red

Two systems behind the retina

• “where” (path to parietal cortex, dorsal)

• “what” (path to temporal cortex, ventral)\

! there’s a strong modularity within each system

Bottom-up / Top-down processes

Perception occurs on the basis of:

• bottom-up (data-driven) process

• top-down (knowledge-driven) processes (e.g. context, priming)

BUT! the orientation of an individual part is sometimes crucial 

Perceptual organisation

Segregation of figure and ground

Perceptual interpretation

Occurs on the basis of organising principles (Gestalt principles), e.g. proximity, similarity, continuity

Perception of depth

Depth cues: binocular & monocular

• binocular: binocular disparity, covergence

• monocular: occlusion, linear perspective, shadow, motion parallax

Perception of size

Depends on perceived distance (depth)

• size constancy

• shape constancy

• lightness constancy

• color constancy

Types of learning

Habituation

When our behavioural response to a stimulus decreases; allows to focus on what is new 

Sensitisation

When our behavioural response to a stimulus increases

Nonassociative learning

Occurs during a repeated exposure to a stimulus

Dishabituation

An increase in a response because of a change in something familiar (e.g. when loud air conditioning is turned off, we notice it)

Classical conditioning

A type of associative learning. Occurs when two stimuli are learned to be associated with each other (e.g. Pavlov’s dog)

Second-order conditioning (related to cc)

When a conditional stimulus (CS) is paired with a new S, the new S produces conditional response (CR)

Extinction (related to cc)

The association between the CS and CR can be eliminated by repeatedly presenting the CS alone

Spontaneous recovery (related to cc)

Increase in CR after extinction and a resting interval

Stimulus generalisation (related to cc)

The CR can also be elicited by stimuli that are different but similar to the CS

Discrimination

• CS appears → reinforced stimulus

• CS disappears → unreinforced stimulus

Why an organsim cannot learn all and any association (related to cc)

• biological constraints

• conditioning requires contiguity such that learning only occurs when the CS is presented before the unconditioned stimulus (US)

• contingency - the CS should be informative with respect to the chance that the US is offered

=> the CS actually functions as a sort of predictor of the US; the CR is a reaction in preparation to the US

Operant / Instrumental conditioning

A form of learning in which the consequence of an action (response) determines the likelihood that it will be performed again, i.e. carrot and stick

Law of Effect (Thorndike, 1898) (related to oc)

Behaviour is governed by its consequences; reward > punishment

B. F. Skinner (1904 - 1990)

One of the most influential researchers of operant learning

How can operant conditioning be applied

Partial-reinforcement extinction effect

Partial reinforcement leads to less extinction than continuous reinforcement

Schedules of reinforcement

• Fixed-Ratio (FR) e.g. food after x responses

• Variable-Ratio (UR) e.g. food after on average x responses

• Fixed-Interval (FI) e.g. food after 1st response after 5 minutes

• Variable-Interval (VI) e.g. food after 1st response after on average 5 minutes

Tolman (1948)

Learning involves not only a change in behaviour but also the acquisition of new knowledge

Contiguity & contingency in operant conditioning

• Contiguity - learning only occurs when the reinforcer OR punishment immediately follows the response

• Contingency - the reinforcer OR punishment should occur more likely after the response than otherwise

  • without contingency → learned helplessness

Memory

The organisation of stimuli from the past; it’s also the nervous system’s capacity to retain and retrieve skills & knowledge

Memory operates in 3 phases …

• Encoding

• Storage & Consolidation

• Retrieval (recall & recognition)

Evidence for the fact that STM has limited capacity

• memory span task: “magic number seven”

• by recoding (separating into chunks) → expansion of capacity

• items disappear as a result of decay & replacement

Evidence against Atkinson & Shiffrin’s model

• Craik & Watkins (1973) - “repeat the most recent word starting with g”

• Nickerson & Adams (1979) - “does the Lincoln on the penny face R/L

=> Memory is an active process requiring attention

Modern memory theory

• STM → working memory - information that one's thinking about at the moment.

• LTM - information, stored during longer intervals, which currently not actively used.

Processes that promote later recall

• Depth of processing: shallow (form) vs. deep (meaning)

• Understanding (having context) : a schema is helpful

Memory consolidation 

The neural process by which encoded information becomes stored in memory

• fragile potential memory contents are transformed into a more permanent state

Long-term potentiation (LTP) 

Strengthening of a synaptic connection, making the postsynaptic neurons more easily activated by presynaptic neurons.

=> After rehearsal → reconsolidation

Good retrieval cues

• re-create the context in which the original learning occured → context reinstatement

• re-create the state of mind

• a richer encoding context results in better recall → encoding specificty principle

Explicit / declarative memory (LTM)

Requires conscious effort

• episodic memory - personally experienced events

• semantic memory - facts & knowledge

Implicit / nondeclarative memory

Does not require conscious effort / cannot be verbally described

• classical conditioning - associating 2 stimuli elicits a response

• procedural memory - motor skills & habits

Amnesia

A deficit in LTM in which the individual loses. the ability to retrieve vast quantities of information

• retrograde - loss of past memories

• anterograde - no new memories

Memory failures aside from amnesia

• an inability to remember (absentmindedness, decay)

  • absentmindedness - the inattentive / shallow encoding of events

  • memory decay - forgetting overtime; causes include metabolic processes & interference ← forgetting curve (Ebbinghaus, 1885)

• memory reconstructions (bias, misattribution, suggestibility)

  • memory bias - the alterations of memories so that they become consistent with current beliefs / attitudes; even flashbulb memories are biased / unreliable

  • source misattribution - distortion that occurs when one misremembers details of a memory

  • suggestibility - the development of biased memories from misleading information ← (Loftus & Palmer, 1974)

Components of knowledge: types of mental representations

• Symbolic representations (cat)

• Analogical representations (🐱)

  • In a certain way, analogical representations are different from pictures, since people don’t have photographic memory

Normative decision theories

Define how people should make decisions

• According to expected utility theory, decisions should be made to maximise the outcome; this should depend on:

  • the values of alternative options

  • the probabilities associated with the alternative options

Descriptive decision theories

Indicate how people actually make decisions

Heuristics

Shortcuts used to reduce the amount of thinking that is needed to make decisions

• heuristic thinking often occurs unconsciously

• heuristic thinking allows us to think more quickly

• heuristics can also result in errors or faulty decisions

Anchoring

The tendency to rely on the first piece of information encountered or information that comes most quickly to mind

Framing

The tendency to emphasise the potential losses or potential gains from at least one alternative

• loss aversion - tendency to regard losses as more significant than gains of the same size

Availability heuristics

Making a decisions based on the answer that most easily comes to mind

Representativeness heuristics

Making a decision based on how typical an individual / object is in a certain category

Affective forecasting heuristic

The tendency for people to overestimate how events will make them feel in the future

The paradox of choice

When too many options are available, people experience conflict and indecision

Intelligence

The ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly

IQ

IQ = Mental age : Chronological Age x 100 (Binet, 1911)

• Deviation IQ - measured in comparison to an average adult

• tests for children: Binet test, Stanford-Binet test, WISC

• tests for adults: WAIS / WAIS-R, SAT; non-verbal: Raven’s Progressive Matrices Test

=> intelligence tests have high reliability & high predictive validity (while the latter depends on a job…)

Psychometric approach

An attempt to understand the nature of intelligence by studying the pattern of results obtained on intelligence tests

• Is the intelligence a single ability or a set of abilities?

  • Spearman (1904): general intelligence (g) + specific abillities

  • Cattel (1971): fluid vs. crystallised intelligence

• Measures of specific abilities correlate with g

Genetic and environmental influences on intelligence

The score of an intelligence test is affected both by genes and the environment (nature & nurture)

• Genetic influences are explored through twin & adoption studies

• Environmental influences on intelligence:

  • impoverished vs. enriched environments

  • environmental factors such as prenatal & postnatal factors, e.g. education, SES

Heritability (formula)

Measures how important genetics is to a trait

• H = Genetic variance : Phenotypic variance

Prenatal development

At the moment of conception, all cells have the same genetic code, yet they start to differ after 14 days

• that is because different cells are exposed to different environments

Teratogens

Substances that disrupt a healthy neural development, such as alcohol

Consequences of maternal stress & starvation

• Maternal stress leads to increased vulnerability to anxiety and depression

• Maternal starvation leads to increased risk of schizophrenia and cardiovascular diseases