TASK 1 - RT Flashcards
cognitive psychology
= study of mental activity as an information-processing problem
- identify internal processing (= acquisition, storage, usage) of information that underlies observable behaviour
- adjusting/changing input and observing output –> what secrets are happening
cognitive psychology
- assumptions
1) mental representations: every person has individual, internal mental presentations of an object (e.g. when somebody tells you ‘ball’ we think of different things: object, description, mathematical formula)
- context dictates which representation is most useful
2) internal transformations: we do not directly perceive and act in the world: our perceptions, thoughts and actions depend on internal transformations/computations
- information is obtained by sense organs –> something secret happens (ability to comprehend and recognise it as something we already know/remember) –> choose appropriate response
mental representations
- Posner’s letter matching task
1) two letters are presented simultaneously in each trial
2) evaluate whether both letters are vowels, consonants or one and one
3) presses one button if letters are from the same category, and the other button if they are from different categories
= we have multiple representations of stimuli; response latencies reflect degree of processing required
–> 1. physical representations 2. phonetic representation 3. category representation
internal transformations
= recognition/comparison process operates either simultaneously or successively
a) parallel: reaction time should be independent of the number of items in memory set
b) serial: reaction time should slow down as memory set becomes larger –> time is required to compare an item with a large memory list than with a small memory list (4 items take longer to compare than 1)
internal transformations
- parallel processing
- word superiority effect = participants are most accurate in identifying target letters when they are part of a word (word condition = fastest response time)
1) stimulus is shown briefly (words, nonsense, X letter strings)
2) participants are asked which of two target letters was presented (A or E)
= when reading a list of words, we activate representations of words and their letters in parallel –> facilitates performance as both provide info about target
internal transformations
- serial processing
- Sternberg’s task = compare sensory information with representations that are active in memory
1) participant is presented with set of letters to memorise (1, 2, 4 letters)
2) single letter is presented
3) decide if this letter was part of the memorised set
4) presses one button to indicate ‘yes’, it was part of the memory set or ‘no’
= reaction time increased in a linear manner with set size –> support serial processing
constraints on information processing
- participants are not able to compare target item to all items in memory set simultaneously (parallel)
- specific constraint to system that you are investigating (task-specific constraints) or general processing constraint (people can only do a certain amount of internal processing at one time)
constraints on information processing
- Stroop task
1) present list of words
2) ask to name the colour of each word as fast as possible (matching colour and word or not)
= faster response when words match the colour
1. representation corresponding to colour of each stimulus 2. representation of colour concept associated with each word –> activated, irrelevant to the task
- activation of representation based on word rather than the colour of the word appears to be automatic
reaction time
= speed with which a participant make their judgements
- mental chronometry = the study of organisation + timing of mental processes
- -> mental events occur rapidly and efficiently = we do not only measure correctness but also time = finer analysis of internal processes
reaction time
- operational definition
= time between onset of stimulus and overt response to that stimulus (e.g. button press)
- trials are repeated to get a reliable mean RT (mRT)
- participant intends to be as fast as possible without making errors
- practically, allow errors and take mean time
reaction time
- theoretical definition
= minimum amount of time needed by the participant to produce a correct response
- instructed and trained to raise validity: rather accept small proportion of errors than perfect performance to avoid risk that participant takes more time than actually needed (false results)
- does not take into account errors, perfect assumption
reaction time
- PROS
- time can be measured; actual variable of interest rather than an abstraction
- highly sensitive to subtle differences between conditions
- often displays an orderliness that encourages construction of models of the underlying information processing
- ratio level: can be directly interpreted in a physical sense; meaningful 0 point, linear
reaction time
- CONS
- only the end product of cognitive processing: the actual cognitive functions are hidden
- -> infer backwards: assumptions are being made about contents of the black box/underlying
- can’t use it for more complex tasks: they usually allow for more freedom leading to individual differences and variations within participants over time
Donders’ subtraction method
= duration/change of stages
- construct two tasks that differ only in a single component of processing
- measure RT in both tasks
- subtract the RTs
- outcome is duration of the single component (influence of the independent variable
stages of mental comparison
1) encode/identify the visible target
2) compare mental representation of target + representation of items in memory
3) decide whether target matches one of memorised items
4) respond according to decision
