Reaction Time

Question 1

Donder’s Substraction Method

Answer 1

Donder built differing experiments with tasks that built up on one another.

The principle is that one can substract the simpler tasks from the more advanced tasks in order to calculate what the Reaction time for an advanced task is.

1) Signal Perception + Motor Response
2) Signal Perception + Signal Discrimination+ Motor Response
3) Signal Perception+ Signal Discrimination+ Motor Choice+ Motor Response

Assumptions :

• pure insertion : there are no interactions between the cognitive components of a task.
• Seriality –> the different processing stages do follow each other in a serial manner (input - transformation- output).
• Cognitive Processes are independent from one another.

Question 2

Memory set paradigm ( sternberg)

Answer 2

Multiple subtraction method- how fast do we search memory ?

• Participants are presented one to four items and afterwards are presented with multiple items- and need to say whether the item they see is among the items they get shown.
• this tasks, focuses on short memory retrieval. Relating the reaction time and the amount of items that need to be discriminated to one another.
• With each added factor the Reaction Time of the Participant increases.

The different added factors than get manipulated ( size of the letters / stimulus degradation). If that happens at differing process stages. This will cause an additive effect on the reaction time.

–> if both processes operate on the same mental process- there will be an interactive effect on the total Reaction time.

Question 3

Limitations to the additive factor method

Answer 3

Stages are not sequential: AFM cannot be applied to circumstances when two factors work on different features of a stimulus (e.g. location/ identity), because then parallel processing and temporal overlap of stages would occur

• RT would be shorter than sum of stage durations, violating AFM assumptions
• An interaction would be observed and AFM would overlook the existence of 2 separate stages
  AFM only gives a number of stages, order is usually logically derived

Stage robustness: the pattern of additivity/ interaction among factors doesn’t change if they’re combined with a new factor.

Accepting the null hypothesis: if one factor only has a small effect at all levels of the other factor, the absence of a significant interaction does not indicate involvement of independent stages.

Question 4

Speed Accuracy trade off ( Limitations of RT Research)

Answer 4

• one of the core problems of Reaction Time measurement.
• the more accurate the participants are supposed to be- the longer the Reaction Time will be.

–> depending on the emphasis of the researcher- the participant focuses either on the speed or the accuracy (not making a mistake)

• People have a strong tendency to avoid error.
• -> slower Reaction Time

Question 5

Reaction Time in Depressed old Patients

Answer 5

• comparison of depressed to non depressed control group.

–> If depression affects response selection and spares stimulus pre-processing, it should interact with stimulus-response compatibility and be additive with visual stimulus intensity.

• Depressed patients displayed longer mean RT than the controls
• Mean RT was shorter for the strong stimulus intensity than the weak stimulus intensity
• Compatible stimulus-response mapping had a shorter RT than incompatible stimulus-response mapping
  Faster reactions for short rather than long fore periods: effect bigger in depressed patients