Task 1 - Reaction Time Flashcards
What is reaction time defined as?
the time interval between the onset of a stimulus and the overt response to that stimulus
- trials should be repeated frequently, to get a reliable mean RT
- assumption: pp intends to be as fast as possible without making errors
What is relevant to know about errors, when looking at RT?
- considering the speed-accuracy tradeoff
- delete error trials to increase RT accuracy
what is the speed-accuracy tradeoff?
- when increasing speed, the number of errors will increase (= reduction in accuracy)
- when decreasing speed, the number of errors will decrease (= increase in accuracy)
- goal: to find the theoretical definition
= unbiased RT (optimum) - to counter it: RT tasks are being repeated with different instructions (= different RT means that will be averaged) -> differnt conditions will result in different extreme emphasise
What is important about anticipation in RT?
participants anticipating a stimulus may affect reaction time
= Predictability influences reaction time
= may underly the speed-accuracy trade-of
What is important about outliers in RT?
- outliers should be removed from RT means, since they confound the general analysis
- normal to remove them from lvl1 analysis, but not from lvl2 (= fraud)
What are Donder´s 3 tasks ?
Donder´s substraction methods
- Simple reaction time (a)
- Go/ no-go reaction time (c)
- choice reaction time (b)
can calculate the:
= duration of response selection (B-C)
= duration of stimulus discrimination (C-A)
What are stages? Theory 1
- two independent stages
- A: task identification of a digit (incl. output)
- B: serial comparison of this code to the representation
- degradation of the stimulus would lead to an increase of the duration of only A, no effect on B
- Additivity (= independence btw. 2 processes)
What is the substraction method?
- construct two task that differ only in a single component of processing
- measure reaction time in tasks
- substract reaction time
- outcome is the duration of the single component
= deleting mental operations from RT
What does pure insertion mean?
The duration of all other processing stages remains the same, when an extra stage is added
= no overlapping processes
! tends to be violated by default?
What does seriality mean? Relevance in Donder´s?
- Processing stages are carried out in a serial manner
- successive stages
- necessary for: sum of durations of individual stages = total RT
- one of the assumptions of Donder´s substraction method (+ Sternberg´s additive factor model)
What is Sternberg´s additive factor model?
A subtraction paradigm presupposes knowledge about the processes/ stages involved in RT
aim: Discover people´s processing stages
assumes seriality + refuses pure insertion
What is the importance of interaction in AFM?
Interaction
= effect of one factor modulated the effect of the other factor
= difference between the simple effects
<-> additivity
if two manipulations mutually modify each other´s effect (= interaction), they must affect some stage in common
What are the language factorial experiments?
factors: independent variables in an experiment
closely linked to AFM
What is the diffusion model?
provide a theory that explains the distribution of RTs of correct responses and errors in a 2 choice RT task
-> information grows in tiny steps
assumes:
- information accumulates continuously during the time between stimulus onset and response
- random noise in the information, due to which response times and outcomes vary from trial to rial
What is the random walk?
- process that underlies the diffusion model
- the information accumulates (incl noise)
- accumulation draws graph to upper/ lower threshold
- if threshold is reached -> reaction occurs
- random noise leads to different reactions
What is the simple reaction time task (A)?
signal perception + motor response
-> there is one possible stimulus and one possible response
what is the go/ no go reaction time task (c) ?
signal perception + stimulus discrimination + motor response
-> there are 2 possible stimuli and 1 possible response
what is the choice reaction time task (b) ?
signal perception + stimulus discrimination + response choice + motor response
-> There are 2 possible stimuli, each of them demanding a different response
-> RT longer (than a) because demands discrimination between two possible stimuli and selection of the correct response among the two alternatives
what is additivity?
Simple effect of one factor is invariant across levels of the other
(interaction = 0 -> independent)
what are the assumptions of Donder´s subtraction method?
1) seriality
2) pure insertion
3) detailed knowledge
what are the implications of Sternberg´s additive factor method?
- seriality of stages
- additive effects
- interaction
what are the limitations of Donder´s subtraction method?
- does not account for RT decreasing after practice (= negative duration)
- the detailed knowledge assumption
- pure insertion assumption (= fails: relies on minimum RT, not mean RT)
what is orderliness?
occurs in Sternberg´s memory search task:
the time required to check every item is independent of the number of items
= linear representation
= exhaustive seach (= not stopping after target has been detected ~ not self-terminating search)
What are the limitations to AFM?
- accepting the H0
- stage robustness
- stages are not sequential
- Simon effect
- only provides the number of stages (order is usually logically derived)
what are the four stages in the additive factors Method?
1) encoding
2) identification
3) response selection
4) motor execution
