Task 1 - Reaction Time Flashcards
Sternbergs memory search task
Presented participants with memory-set of letters, then they had to recall if a letter was part of that set
Sternbergs four primary mental operations
- Encode
- Compare
- Decide
- Response
(then there was debate about their serial or parallel nature)
Word Superiority Effect
In the Sternberg task, participants can answer quicker if the memory set presented is a word
Reaction time (RT)
The time interval between stimulus presentation and response execution.
Used in psychology and neuroscience to infer cognitive processing stages
Donder’s subtraction method
By comparing reaction times between a simple task and a more complex task (which includes an additional cognitive operation), the extra time required for that operation is inferred by subtracting the simple task’s reaction time from the complex task’s reaction time -> isolate a specific mental process
The three assumptions of Donder’s subtraction method
- Serial processing
- Pure insertion (adding a new stage does not alter the duration of the other stages)
- We know the sequence of the stages
Additive Factor Method (AFM)
Sternberg
- You manipulate different factors (e.g., stimulus clarity, response complexity) and measure their effects on reaction time.
- If two factors independently increase RT, they likely affect separate processing stages.
- If two factors interact (i.e., combined effect is more/less than the sum of individual effects), they likely affect the same stage
Speed-Accuracy Tradeoff (SAT)
- Participants try to respond as fast as possible while minimizing errors.
- Some may prioritize speed (faster RT, more errors), while others prioritize accuracy (slower RT, fewer errors)
A-Type
Donders’ A, B and C-Type Tasks
Simple RT: One stimulus, one response - Sensory processing + Motor execution
B-Type
Donders’ A, B and C-Type Tasks
Choice RT: Multiple stimuli, each requiring a different response - Sensory processing + Stimulus discrimination + Response selection + Motor execution
C-Type
Donders’ A, B and C-Type Tasks
Go/No-Go RT: Multiple stimuli, but only one requires a response - Sensory processing + Stimulus discrimination + Motor execution
Assumptions of the AFM
- Information is processed in successive stages
- Does not assume pure insertion
- Manipulating a variable affects only one stage
- If two factors affect different stages, effects will be additive, if they affect the same they will interact
Mental chronometry
Seeks to measure the time course of mental operations in the human nervous system
Ratcliff’s Diffusion Model (DM)
- Used to explain decision making in RT tasks
- Assumes two decision boundaries/thresholds and evidence is accumulated until one of them is crossed
- The can have bias, which means the starting points are different
How to handle outliers in RT
Common methods:
Trimmed means: Remove the fastest and slowest 10% of RTs
Standard deviation cutoff: Remove RTs > 2.5 SDs from the mean
Median RT: Less sensitive to extreme values
Random walk
- A mathematical concept describing a path that consists of a series of random steps.
- Evidence accumulation in diffusion model follows this path.
Important computations
Donders’ subtraction method
RT(C) – RT(A) = Discrimination time (=150 ms)
RT(B) – RT(C) = Response selection time (=100 ms)
