Experimental Psychology: Chapter 1: the evolution of science
LECTURE 1
.Psychology studies human behaviour and attempts to find explanations for it.
Experimental psychology = cognitive psychology = a core discipline that studies
cognitive functions.
(Cognitive) neuropsychology: patients with specific disorders (local brain damage as
opposed to diffuse) allow for more specific and reliable inferences about brain
functioning.
- Dyslexia, neglect (hemi spatial / unilateral inattention), aphasia (trouble producing /
understanding speech), prosopagnosia (unable to recognize faces, including your
own – objects are fine), visual agnosia (unable to recognize visual objects – faces
are fine).
Physiological psychology = neurosciences = investigates the relationship between
mental processes and their biological foundations in the central nervous system (cns).
Certain types of behaviour are accompanied by tractable brain activity. – brain
connected to behaviour
History: the scientific approach to study the human mind is relatively young compared
to other disciplines because;
1) for a long time the human mind was viewed as unique
2) theologists and philosophers argued that the “free will” cannot be examined in a
scientific way as can be done with the laws of nature.
Until Descartes questioned the mind’s “supremacy” and proposed that there is an
interaction between mind and body. So, focus on behaviour that goes beyond “free will”
like reflexes, who can be studied scientifically. (Dualism)
One of the first experimental psychologists is Hermann von Helmholtz; velocity of the
nerve impulse.
,Gustave Fechner discovered the first mathematical law; relationship between the
physical and perceptual world (science and perception): Just Noticeable Difference
(JND).
Darwin: his evolution theory, which stated we all share the same ancestors, (natural
selection and not created by god) justified comparative psychology as a discipline and
allowed scientists to compare behaviours in different species.
Franciscus Donders introduced Mental chronometry. He tested reaction time with
additive factors logic:
Condition A subject hears ‘ki’ – repeats ‘ki’
detection RT
Condition B subject hears ‘ki’ ‘ka’ or ‘ke’ – repeats ‘ki’ ‘ka’ or ‘ke’
detection + discrimination + decision RT
Condition C subject hears ‘ki’ ‘ka’ or ‘ke’ – only repeats ‘ki’
detection + discrimination RT
- still used in modern fMRI research where brain activity in an experimental condition is
subtracted from a control condition. You can, for example, test if a patient has
prosopagnosia.
Wilhelm Wundt (founder of psychology, structuralism) founded the first psychology lab.
Psychology is the science of immediate experience.
Experience exists in three parts: sensations, images and feelings conscious
experience.
,- used analytical introspection as method (this didn’t work, turned out to be wrong).
Around 1920 structuralism disappeared because the method was very unreliable as
the result could not be replicated.
Behaviourism: John Watson. Psychology is the study of the observable (overt)
behaviour. The mental (covert) behaviour cannot be studied scientifically. – part of the
logical positivism movement. Introduced the operational definition = any term you
introduce should be able to be measured (eg hunger = duration of food deprivation
measured in hours). The big advantage is that precise measurements could be made,
thus stimulating comparisons between studies / replications.
Ivan Pavlov: classic conditioning
Skinner: operative conditioning; learning occurs through reward and punishment. In
order to understand behaviour, you have to study the external environment as well as its
effects on the behaviour.
Gestalt psychology: the whole is more than the sum of its parts. Rejected Wundt’s
structuralism (experience is more than a function of sensation) and behaviourism,
because complex behaviours (“the whole”) is more than the sum of its components.
- Max Wertheimer, Wolfgang Köhler, Kurt Koffka – “never trust your eyes” ,
“perspective changes the outcome”
Apparent motion is used to prove this. “experience without sensation”. Two lights that
light up and then extinguish at the right speed / distance appear as 1 object that moves
through space (TV) instead of 2 flashes.
Perception is a construction, not a reflection of the sensation.
- The use of different colours doesn’t change anything – it can still go both ways.
“motion doesn’t know colour.” – same with size, amounts, forms, nothing matters.
, Construction also exists in the auditory domain: you can either hear gallop- rhythm while
2 tones (high-low-high) are played, or 2 separate streams, one high the other low. – if
the frequency difference is too high or speed too fast.
Since the 70s we speak of a cognitive revolution. The computer is now used as a
metaphor for human thinking. In addition, modern imaging techniques, such as fMRI,
have been available since the 80s. neuropsychological patients are increasingly used
as a test of theoretical hypotheses.
Methods in Cognitive Neuroscience
- Experimental research with behavioural measures (eg Reaction Time) or
percentage correct – traditional (no machines used)
- Non-invasive brain imaging techniques – EEG, MEG, fMRI
- Blocking normal brain functioning through pharmacological substances or
Transcranial Magnetic Stimulation (TMS)
- Patients with (preferably) focal lesions
- Computer simulations
Behaviour can be explained on various levels:
- Biological factors: chemical, neural, hormonal, genetic
- Individual factors: learning, psychodynamic and cognitive processes
- Cultural and social factors
Each level has its own research methods. An important distinction is that between
descriptive versus experimental research.
- Descriptive research does not provide information about causality (whether a
causes b), whereas experimental research does.