1. subtractive methodology
Donders’
subtractive methodology

2. IAAF policies consider that there is a limit to how fast a human can react to a start signal. As of 2002, if an athlete left the blocks sooner than 100 ms. after the start signal, he was deemed to have false-started. Some fans think this is wrong and that any reaction after the gun should be allowed.
The best athletes reaction times are usually in the range of 120 mSec (0.12 sec) to 160 mSec.
Tim Montgomery improved that to a near perfect 104 mSec - and came very very close to being false-started. The only sprinter to get closer to perfection was Surin Bruny - who managed a 101 mSec in a the 1999 WC 2nd semi-final.
Burrell's 1991 world record began with a reaction time of just 117 mSec.
In the same race, Carl Lewis reacted in a snail's-pace 166 mSec, probably because he'd deliberately slowed his start due to having an earlier false-start posted against him (this put him at risk of disqualification if he false-started again).
Taking away reaction time, Burrell covered the 100 metres in seconds, Lewis in Lewis was actually the faster runner, but Burrell was the better "gunner".

3. Mental Chronometry
Subtractive Methodology

4. SIMPLE REACTION TIME (RT) TASK
STIMULUS DETECTION
RESPONSE EXECUTION

5. A simple reaction:
There is only one response to a single stimulus.
For example, a light goes on and the instruction is to press a key or a button as soon as possible after the onset of the stimulus. For Donders, this simple RT task (we will call it Task A) could be used as a baseline.

6. SIMPLE REACTION TIME (RT) TASK
STIMULUS DETECTION
RESPONSE EXECUTION

7. CHOICE REACTION TIME (RT) TASK

8. GO/NO GO REACTION TIME (RT) TASK

9. Simple RT
Choice RT
Go/Nogo RT
Choice RT - Simple RT =
Choice RT - Go/Nogo RT =

10. A problem with the Go/NoGo task

11. Go
Respond to Circle but not a Square

12. NoGo
What happens if the subject occasionally responds to the square?
Donders: If this happens once, the whole series must be rejected: for, how can we be sure that when they had to make the response and did make it, they had properly waited until they should have discriminated

13. If the subject responded incorrectly “Go” to the square, maybe he or she also sometimes responded correctly to the circle without allowing enough time to identify it. A kind of “false start”.
How can we be sure that when they had to make the response and did make it, they had properly waited until they should have discriminated.
The subject may simply have responded correctly without waiting to determine if the target is a circle or
a square. Go

14. In other words, the participant may have changed the amount of time he or she allows before responding to the target in the go/nogo task, triggering on some trials very fast anticipatory responses before the stage of identification has been completed. If this were true, the components involved in Task C are not just those which determine performance in Task B minus the added stage of response selection.

15. ????????
Go/NoGo
Choice RT
The subtraction: Choice RT-Go/NoGo RT may not
provide a valid measure of

16. Donders’ method is based on three assumptions.
First, it is assumed that the mental processes of stimulus detection, stimulus identification, response selection and response execution are arranged sequentially, in the sense that the output of one serves as the input to the next.
Second, it is assumed that only one process can be active at each moment in time between stimulus input and response output.
Third, it is assumed that a mental process can be added or omitted without affecting the duration of the other processes, the so-called assumption of pure insertion.

17. The Word Superiority Effect
Skilled readers are faster to identify any letter
in a word than a single letter in isolation.
e.g. HAND vs
###D

18. Cattell
HAND
###D
###D
HAND

19. A modern idea

20. Bottom-up
Feed-
forward
Words
Letters
Features
Excitatory
Inhibitory

22. K on its own is quite confusable with R.
K in WORK is more confusable with D than R
WORK

23. The logic of additive factors
What is a factor?
Any type of stimulus or response can be varied in some systematic way.
We can make letters small or big
BIG SMALL
We can make words familiar or less familiar
BOOK ROOK
We can make shapes easy to see or harder to see

24. The logic of additive factors
Each of these properties of the stimulus (we can do the same for responses) is termed a factor or variable if we wish to make use of it in an experiment.
We can make letters small or big
BIG SMALL
Size
We can make words familiar or less familiar
BOOK ROOK
Familiarity
We can make shapes easy to see or harder to see
Stimulus Quality

25. Why might we want to vary a stimulus or response factor?
Stimulus Identification
Response Selection
Response Execution

26. Why might we want to vary a stimulus or response factor?
Easy vs Hard to See is a Factor (Variable) that affects Stimulus Identification
Stimulus Identification
Response Selection
Response Execution

27. Response Selection. Respond with the hand on the same side as the target object
Compatible Mapping

28. Response Selection. Respond with the hand on the opposite side to the target object
Incompatible Mapping

29. Why might we want to vary a stimulus or response factor?
Easy vs Hard to See is a Factor (Variable) that affects Stimulus Identification
Compatible vs Incompatible Mapping is a Factor (Variable)
that affects Response Selection
Stimulus Identification
Response Selection
Response Execution

30. Why might we want to vary a stimulus or response factor?
Easy vs Hard to See is a Factor (Variable) that affects Stimulus Identification
Compatible vs Incompatible Mapping is a Factor (Variable)
that affects Response Selection
Stimulus Identification
Response Selection
Response Execution
Varying
difficulty
Varying
difficulty

31. Examples of Compatible versus Incompatible Response Mappings.
Respond with your left hand to
Respond with your right hand to
Incompatible response mapping
Respond with your left hand to
Respond with your right hand to
Compatible response mapping
Say white to
Say black to
Incompatible response mapping

32. Task: Respond to the direction of an arrow
using a spatially corresponding keypress.
Right

33. Task: Respond to the direction of an arrow
using a spatially corresponding keypress.
Left

34. Task: Respond to the direction of an arrow
using a spatially corresponding keypress.
Hard to See
Left

35. Task: Respond to the direction of an arrow
using a spatially corresponding keypress.
Hard to See
Right

36. Compatible versus Incompatible Response Mappings?

37. Compatible versus Incompatible Response Mappings?
Task: Respond to the direction of an arrow
using a spatially opposite keypress.
Incompatible Mapping
Left

38. Compatible versus Incompatible Response Mappings?
Task: Respond to the direction of an arrow
using a spatially opposite keypress.
Incompatible Mapping
Right

39. Compatible versus Incompatible Response Mappings?
Task: Respond to the direction of an arrow
using a spatially opposite keypress.
Incompatible Mapping
Hard to see
Left

40. Compatible versus Incompatible Response Mappings?
Task: Respond to the direction of an arrow
using a spatially opposite keypress.
Incompatible Mapping
Hard to see
Right

41. The Factors: Easy vs Hard to See and Compatible vs Incompatible
have statistically independent effects on RT
EASY TO SEE
HARD TO SEE RT
500MS
550 MS
600 MS
COMPATIBLE RESPONSE
INCOMPATIBLE RESPONSE
650 MS
ADDITIVE EFFECTS

42. Easy vs Hard to See Compatible vs Incompatible Responses
Stimulus Identification
Response Selection
Response Execution
Easy vs Hard to See
Compatible vs
Incompatible
Responses

43. Letter Identification
Orthographic Lexicon
Phonological Lexicon
SPEECH OUTPUT
PRINT
Grapheme-
phoneme conversion
rules
Semantic System
?????

44. Letter Identification
Orthographic Lexicon
Phonological Lexicon
SPEECH OUTPUT
PRINT
Grapheme-
phoneme conversion
rules
Semantic System
A factor affecting Letter Identification?

45. Letter Identification
Orthographic Lexicon
Phonological Lexicon
SPEECH OUTPUT
PRINT
Grapheme-
phoneme conversion
rules
Semantic System
A factor affecting Letter Identification?
Easy versus Hard to See
Pencil vs
Pencil

46. Letter Identification
Orthographic Lexicon
Phonological Lexicon
SPEECH OUTPUT
PRINT
Grapheme-
phoneme conversion
rules
Semantic System
A factor affecting the Orthographic Lexicon (i.e.
the speed of lexical access)?

47. Letter Identification
Orthographic Lexicon
Phonological Lexicon
SPEECH OUTPUT
PRINT
Grapheme-
phoneme conversion
rules
Semantic System
A factor affecting the Orthographic Lexicon (i.e.
the speed of lexical access)?
High Familiar vs Low Familiar Words (Familiarity)

48. Examples
Familiarity
Familiar Words: HAND, BOOK, TREE, LIFE
Less Familiar Words: PLUM, ROOK, SNIP, HIVE
Easy to see:
HAND
FAMILIAR
Hard to see:
HAND
Easy to see:
PLUM
LESS FAMILIAR
Hard to see:
PLUM

49. Task: Name the word as quickly and as accurately as possible.

50. The Factors: Easy vs Hard to See and Familiar vs Less Familiar Words do not have statistically independent effects on RT
EASY TO SEE
HARD TO SEE RT
500MS
550 MS
600 MS
FAMILIAR WORDS
LESS FAMILIAR WORDS
650 MS
naming latency
INTERACTIVE EFFECTS

51. Letter Identification
Orthographic Lexicon
Letter Identification
Orthographic Lexicon