Inferring models of information processing from factorial designs: Additivity and interactions in reaction time experime

1. Inferring models of information processing from factorial designs:Additivity and interactions in reaction time experiments and theirimplications for independent stages, cascaded processing, and theinteractive-activation framework.

2. Imagine you are asked to do two tasks. One task takes 30 minutes the other task takes 1 hr. What is the simplest thing we can infer?

3. Imagine you are asked to do two tasks. Both tasks take 1hr. What can one infer?

4. Imagine you are asked to do two tasks. One task takes 30 minutes the other task takes 1 hr. What is the simplest thing we can infer? The 1hr task is harder? – nope! Imagine that the two tasks are cleaning the bathrooms and doing laundry. Though it may take 30 minutes to clean the bathrooms, you must work the entire time, whereas with laundry, the majority of time is spent waiting for the machines to finish.

5. Imagine you are asked to do two tasks. Both tasks take 1hr. What can one infer? That both tasks are equally difficult? – nope! Imagine that both tasks involve doing laundry at the Laundromat. In one case you have to wash and dry a load of towels, in the other case you have to wash and dry a load of towels and 4 loads of delicates. The latter case requires more work, but still requires the same amount of time.

6. This is one example of the problem facing cognitive psychologists when inferring models from RT. Next, I will discuss a couple of the more popular methods for inferring models from RT.

7. How long does a process take? How are processes organized (stages)? What are the characteristics of a process?

8. How long? Donder’s Subtraction Method Organization? Sternberg’s Additive Factors Method Characteristics? Dual task Slopes

9. Donders Method Also known as the Subtraction Method The time between the presentation of a stimulus and a response is occupied by a series of successive processes or stages It is possible to estimate the time of stage through subtraction.

10. How to: Find two tasks that differ only with respect to the stage of interest. Subtract the RT for the two tasks The residual time is the RT of the stage.

11. Where it is used Cognition in the early 60s Neuroscience today

12. Cognition Example Simple Detection press the button when the target appears on the screen (use blue and red items) Colour Detection press button when the blue item appears on the screen (use blue and red items).

13. Cognition Example

14. Therefore, colour processing takes 25 msec.

15. Neuroscience Example Simple Detection press the button when the target appears on the screen (use blue and red items) Colour Detection press button when the blue item appears on the screen (use blue and red items).

16. Neuroscience Example

17. Assumes RT is a sum stages stage durations are independent it is possible to add and subtract stages pure insertion

18. Sternberg’s Additive Factors Manipulate two or more factors within the same task. If they interact, they affect the same stage of processing. If they are additive, then they affect separate stages of processing. Does not allow you to estimate the duration of a processing stage.

19. Imagine you ask people to read words aloud. You factorially manipulate stimulus quality, and word frequency (how often the word is encountered) Additive Effects

21. Therefore, stimulus quality and word frequency affect different processing stages. Additive Effects

22. Additive Effects

23. Imagine you ask people to read words aloud. You factorially manipulate stimulus quality, and repetition (whether or not the word occurs more than once) Interactive Effects

25. Therefore, stimulus quality and affect the same stage of processing. Interactive Effects

26. Interactive Effects

27. Assumes RT is a sum stages stage durations are independent An interaction between two factors that affect separate stages can arise if the stages occur in separate channels.

28. Dual Task Used to determine the characteristics of a process Subjects perform two tasks simultaneously individually The two conditions are compared.

29. Bottlenecks, resources, and attention Broadbent, Treisman, and others dichotic listening subjects hear auditory information over two independent channels attending to one channel seriously limits perception of the other channel (nothing gets in). information does not “get in” to the system. lead to the idea of early selection

31. Bottlenecks, resources, and attention Deutsch & Deutsch,Keele,and others dichotic listening subjects hear auditory information over two independent channels attending to one channel limits perception of the other channel (but information is processed to semantics). information does “get in” to the system. lead to the idea of late selection

32. Bottlenecks, resources, and attention Kahneman, Navon, and others argued that both types of selection arise because of the distribution of attentional resources. It has been argued that difficulty only exists in a “limited resource” context (Wickens, 1984)

33. Attentional Demands Conceptualizing attention as a resource introduces the question “How resource demanding is a process?” or in the extreme “Does a process demand resources?”

34. If a process does not demand resources, then it can proceed unaffected by other processes. If a process demands resources, then it can slowed or stopped. Any stage can have resources, and/or Resources can allocated from a central pool

35. Dual Task Imagine you ask subjects to perform two tasks either at the same time or independently Task 1: Press a button when you see a light. requires visual processing and a decision Task 2: Press a button when you hear a tone. requires auditory processing and a decision

36. Does making a decision require resources?

38. Does making a decision require resources?

39. Dual Task Imagine you ask subjects to perform two tasks either at the same time or independently. Tell the subjects to give priority to Task 1. Task 1: Press a button when you see a light. manipulate stimulus quality (resource demands) requires visual processing and a decision Task 2: Press ‘X’ if consonant, press ‘Z’ if vowel. requires visual processing and a decision

45. Visual Processing Resources

46. Resources Demands

47. Resources Demands

48. Resources Demands

49. Resource Demands

50. Resource Demands

51. Dual Task: Predictions Task (light detection) will be affected by the bright/dim manipulation When the tasks must be performed simultaneously they will take longer (both require decision process) There will be an effect of the bright/dim manipulation in Task 1 on Task 2 when they are performed simultaneously.

52. Dual Task

53. Dual Task