Task 1 Flashcards
Why do we meassure reaction time (RT) ?
- Mental processes have no physical characteristics like weight or color that can be manipulated or measured
- But mental process take time (which is a pysical property)
What is meant by Simple RT ?
- One possible stimulus (sensory) and one possible response (motor)
- Short summary: Sensory + motor
- Example: 1 button, hit when you see a stimulus
What did donders subtraction method wanted to find out ?
- how fast do we process external stimuli
Describe the Method of Donders Subtraction Method:
- Task A: Simple RT
- Task B: 2 Choice RT
- Task C: go nogo
What is meant by 2 Choice Rt ?
- Example: 2 buttons, hit left when you see one stimulus, right when you see the other one
- Short summary: sensory + discrimination + response selection + motor
What is meant by Go nogo RT?
- Example: 1 button; hit when you see one stimulus, withhold when you see another
- Short Summary: sensory + discrimination + motor
What can we compute based on the Donders Subtraction Method ?
- Discrimination time = RT (C) – RT (A)
- Response selection time = RT (B) – RT (C)
What are the problmes with the donders subtraction method?
- Pure insertion does not exist (identified in go nogo task -> negative durations)
- It is all based on intuitive arguments not emparical
- Assumptions are to strong
What are the assumptions of the subtraction model?
- Seriality: Processing stages are successive & and strictly follow serial processing
- We assume to know the sequence of the stages
- Pure insertion: if we insert a stage, the rest does not change
- > Sensory and motor process are completely identical in different task
How could you describe the overall Method of Donders subtraction Model?
- Construct two tasks that differ in one component of processing and measure RT in both task -> then subtract the reaction times
- U get the duraction of the single component
What is the operational definition of RT ?
Opertaional defintion:
- Time interval between stimulus onset and over response
- Based on the assumption that one acts as fast as possible
What is the theoretical definiton of RT ?
-Minimum time need to react as fast a possible
What are “ERRORS” in RT test?
False response to a stimuli
o Not paying attention
o Confused by the instructions
o Speed over > accuracy -> Also known as the speed accuracy tradeoff
Explain the Speed accuracy tradeoff:
- Speed emphasis lots of errors -> producing chance accuracy
- Optimal would be normal speed emphasis instructions to gain maximum accuracy
- It is all about being fast and accurate !! ( But in general people are avoiding erros )
What are outliers ? And when do they occur ?
- When averaging the RT
- Those are extremely slow or fast reactions which effect mRT SD and variance
How do ouliers occur ?
o Inattentiveness of the stimuli (slow)
o Incomplete stimulus analysis
o Or due to guess (fast)
How can outliers be avoided ?
Trail lvl 1
- Clear instructions
- Feedback
- Keep the experiment short
- Or use either: Medians trimmed means or C standard deviation method
Subject lvl 2
- Avoid ill particpants
- But do not just trough them out for no reason
What are the stages of Information processing?
- Encoding
- Identification
- Response selection
- Motor execution
What are the cons of RT methods?
- Reflects only the end product of cognitive processing: the actual cognitive functions are hidden
- We must assume those functions
What was the goal of Sternbergs memory Serach Task?
- It Identifies that our memory uses serial processing
- tested the hypothesis that “If comparison could be done simultaneously for all items, the RT should be independent of the number of items in the set”
- > Conclusion RT was not indeppindent !
What was the method of Sterberg memory task ?
- In each trial participants see a set of letters to memorise (1/2/4 letters)
- Then they see a letter and must decide via button press whether it was part of the set (two buttons, yes and no)
- dependent variable is reaction time.
- > USED REPEATED SUBTRACTION
What is the task of the particpant in the Steinberg memroy task ?
- Encode: participant must identify the visible target.
- Compare: participant must compare the mental representation of the target with the representations of the items in memory.
- Decide: participant must decide whether the target matches one of the memorized items.
- Respond: participant must respond appropriately for the decision made in step 3.
What is menat by exhaustive search ?
- No stop when item was found -> We Search always till we have reached the end of the stage
- RT for pos answers = RT for negative answers
What is meant by self terminating serach ?
- Searching stops when the item was found
- RT for postive answers < RT negative
Which of the two search startgies does our brain use and why ?
- Our brain uses the exhaustive search since the mean reaction time SLOPE for positive and negative responses was identical
Explain the set size function:
- It gives us the MEAN RT
- Mean RT = Intercept + slope * set size (Number of items in memorized set)
o Intercept = Time needed to scan zero items
o Slope = the duration of comparing 1 item in memory
Y axis = Reaction time
X axis = set size
What is the Goal of Sternberg Additive factor model ?
- Discovery of independent stages
- How many stages are there, and what do they do?
What are the Assumptions of Sternberg Additive factor Model ?
- Serial processing
- Independence
- Stage robustness
- Manipulations affect duration, not quality of output
What is meant by the assumption of Serial processing
- Assume that in a sequence of stages each does some operations and hands output to the next
What is meant by the assumption of independency?
- Later stages of processing cannot ‘compensate’ for any delays earlier on
What is meant by the assumption of Stage robustness
- the pattern of additivity or interaction among factors does not change if the factors are combined with a new factor.
What are the implications of the additive factor Model ?
- Total RT is simply the sum of the stage durations
- Additive effects – if 2 manipulations affect different stages, the effect of one will not depend on the other (lines are completly parallell and have a different intercept)
- Interaction – if 2 manipulations modify each other’s effect, they must affect a stage in common (lines are not paralle and have the same intercept
What if the intercepts are different but the slopes are identical in a AFM Graph ?
Both factor impact differnt stages
-> Additive
What if the intercepts are the same but the slopes are different in a AFM Graph ?
Both factors effect a stage in comman
-> Interactive
Whata are similiarities of the AFM Model and the SDM ?
- Both assume successive stages (seriality)
Whata are differnces of the AFM Model and the SDM ?
- Only DSM Assumes pure insertion
- Different Goals:
o DSM duration of an inserted stage
o AFM Discovery of independent processing stages
Name an example of paralle processing:
- Word Superiority Effect (look at the word document for set up )
Name an exmaple of serial processing:
- Posner letter matching Task (look at the word document for set up)
What is meant by Factor ?
- Is an independent variable in an experiment
- Example: gender is an independent variable on reaction time
What is meant by Levels ?
- Levels: The set of values of a factor are called its levels.
- Example: As an gender male, female
What is meant by Condition ?
- is the combination of each possible factor lvl
What is meant by Effects ?
- Factor F (gender) has two levels, F1 and F2. A effect is the difference between the two levels
What is meant by Simple effect ?
- the effect of (one factor = quality) at one particular level of another factor (dose L)
What is meant by Main effect ?
- is the mean of all the simple effects
What is meant by interaction ?
- If the simple effect of one factor (say, quality) varies with the level of another factor (say, dose), then we say that the two factors interact
What is meant by Additive effects ?
- If, the (simple) effect of quality is invariant across levels of the dose factor, their interaction is zero, and quality and dose have additive effects
Stages in the AFM are calles also ?
Mental modules
Whata was one major finding regarding the AFM Model ?
- That with practice only the intercept get reduced
- The slope stays the same
What do cognitive psychologist study ?
- Study of mental activity / functions of the mind
- Seek to identify internal processing
What is meant by the diffusion model ?
- It explians the distribution of both correct and errors in a 2 choice RT task
- In general Information is very slowly dripping in which is why you can right away choose between on or the other option
- Some of the Information might be compatible with both choices
- We have two decison boundaries (treshold) if too much evidence goes in to the one direction we choose the option
What are the benefits of RT ?
-> Cheap and easy to measure
