mental chronometry - uni-muenchen.de · 2018. 11. 6. · c1 c2 + p1 p2 c1 c2 p1 p2. 20 zhuanghua...

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Mental chronometry

Zhuanghua Shi (Strongway)

2https://www.youtube.com/watch?v=fwb4aNkcofI

Airport Check

Zhuanghua Shi, LMU, Munich3

Bistable image

Mamassian & Goutcher, 2005, JOV5

Naming the color of the following words

RedGreenColorGSN

YellowBlue

GreenZhuanghua Shi, LMU, Munich6


Mental processes and Reaction time◻ Mental processes requires some time◻ Speed of process correlates with cognitive and

motoric functions◻ We can infer inner mental processes and

mechanisms by investigating response times (RT)

Mental Chronometry

Mental processes

Stimuli Responses

Mental Chronometry

Mental chronometry is the use of response time to infer mental processes. The way for this is the manipulation of the tasks and/or of variables determining the behavior of participants in the tasks.

Mental chronometry is one of the core paradigms of experimental and cognitive psychology.

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Mental processes and Reaction time

■ It is generally assumed that mental processes is constructed with multiple modules.

■ By observing different reaction times under different conditions, processing time could be observed.


Perception Cognition Motor response


Mental processes and reaction time■ Assumptions and paradigm

◻ the temporal sequencing of information processing in the human brain.

◻ Manipulation of the tasks/stimuli → observe the time course of mental operation

Task 1: simple detection

Task 2: discrimination task

Detection

Detection Discrimination

Response

Response


Main goals

■ To determine components and structure of mental processes (i.e., cognitive modules)

◻ Number of subcomponents◻ Processing time◻ Serial, parallel or cascade

Reaction time

RESPONSE

Reaction time

RESPONSESTIMULUS


History

■ 1822 Francis Galton◻ People who reacted faster are more

intelligent than others

■ 1850 Hermann von Helmholtz◻ Simple reaction time◻ Neural transmission time ~ 30 m /s


History■ 1868 Franciscus Donders: Subtraction method

◻ Duration of subcomponent can be measured by subtracting two tasks which only differ that component

■ 1885 J. Merkel discovered the response time is longer when a stimulus belongs to a larger set of stimuli

■ 1951 Hick further developed Hick’s law

■ 1964 E. Roth demonstrated correlation between IQ and RT


History■ 1969 Robert Sternberg devised a

memory-scanning task, and developed the additive factor method for dividing RTs in successive stages

■ 1979 ~ Modern methods◻ Cascade model◻ Diffusion model


Donders’ subtraction method

■ Donders (1868)The idea occurred to me to interpose into the process of the physiological time some new components of mental action. If I investigated how much this would lengthen the physiological time, this would, I judged, reveal the time required for the interposed term. (Donders, 1969, p418)

◻Assumption of ‘pure insertion’: ■ Task A has all the stages of

Task B lacks an extra process, then■ Extra process can be measured by:

RTA-RTB

RTA

RTB


An example

■ Comparison of different tasks◻ Simple Detection◻ Choice Reaction◻ Go/No-Go

SD

SD

SD

MR

MR

MR

DIS

DIS

RS

• SD: Stimulus detection; • DIS: stimulus discrimination• RS: response selection; • MR: motor response

RT(A)

RT(B)

RT(C)

Response selection = RT(B) – RT(C)

Stimulus discrimination = RT(B) – RT(C)


Example: letter matching (Posner)

■ Several tasks associated with recognition of a pair of letters◻ Physical match task

■ e.g. AA →same, AK→different◻ Name match task

■ e.g. Aa → Same, Ak → different◻ Rule match task (vowel/Consonant)

■ e.g. AE → same, AB → different■ Using the subtraction method the cognitive processes

associated with each of these tasks can be approximate determined.


Posner’s letter matching studies

■ Name match: 64 ms (623 -549 ms)■ Rule match: 178 ms (801 - 623 ms)

Physical match

Name match

Rule match

AA, ee

Aa, Ee

AE, CD

549 ms

623 ms

801 ms

Problems with the method of subtraction

■ Any potential problems?■ Transitivity problem

■ Do individually isolated durations sum up to the duration of the conditions in which they all take place?


C1 C2 P1 P2+

C1 C2 P1 P2


Problems with the method of subtraction

■ Pure insertion ◻ Assumption: Insertion/removal of processing stages

does not influence other processing stages (i.e. they are independent)

◻ Sub-modules should be independent and serial

■ Külpe (1893) – criticism: ◻ insertion of a new process → changes of the whole

task


Sternberg’s additive-factor method

■ If two factors affect two different stages, then their effects on the overall RTs shouldbe additive ones.

F G H



■ If one modulates F, changing its latency from RTa1 to RTa2 and one modulates G, changing its latency from RTb1 to RTb2, then the two changes can be described by:

■ Applying both manipulations:



■ When two factors show an interaction effect on the RT, two factors affect at least one common processing stage F G H

H1 H2

RT G1G2

H1 H2

G1G2

H1 H2

G1G2


Example: Sternberg Memory Scanning

■ Memory scanning: to identify if a probe item is in a memory list or not (Sternberg, 1969)


Example: Sternberg task

■ Stimulus quality ■ set size

◻ are two additive factors

What if we observe no interactions?

■ Manipulations affect independent processes■ or the statistics is under power?

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Example: AFM in cognitive neuroscience

■ Dehaene (1996) ◻ The organization of brain activations in number

comparison: Event-related potentials and the additive-factors method. J Cogn Neurocsci 1: 47–68.

◻ investigated a simple task of number comparison: A number is present on the monitor and subject has to compare if the number is above or below five.

◻ Factors ■ Input: Arabic digits / spell numbers (4 / four)■ Comparison: Near 5/ far from 5■ Response: dominant / non-dominant hand


Cont.

■ Four stages processes

◻ According to AFM, a variable that affects overall reaction time by varying the time to complete one stage will be additive with the effects of factors that affect other stages.

comparisonencoding Response selection Checking error

Arabic digits/ Spelled numbers Close/Far

Non-dominant /Dominant hand

Error/Correct trials


An example of AFM

Close/far Non-dominant/Dominant hand

Arabic / spelled numbers

EEG and fMRI studies showed these four factorsprocessed in different regions


Does AFM make sense?

■ Partially■ No problem with ‘pure insertion’

◻ Manipulation of the duration of a processing stages

■ Comparison between one and the same type of tasks◻ Criticism of Külpe does not hold


Problems with AFM

■ Basic assumptions◻ Factors can affect certain processing stages, while leave

other stages unaffected◻ Stages should not temporally overlap◻ Discrete serial assumption

■ Problems with the reversed inference◻ Additive effects of two factors does not necessarily mean

that two independent stages■ Independence is sufficient, but not necessary, to lead

additive effect■ If p then q → if q then p?


Cascaded processes model■ McClelland (1979)

◻ A series of processes cascading activation from an input level to an output level. Thus it allows a given processing level to start transmitting output (activation) before it has finished processing.

time

How is response time determined in cascade model?■ Accumulation of response unit activates in time■ All processing stages influence this activation

more or less simultaneously


time


Accumulation model and diffusion model

■ Accumulation models◻ Decision information accumulates over time◻ When the accumulated information reach a boundary

(e.g. threshold), a response is made.

(Smith, Ratcliff, 2004)


Accumulation model and diffusion model

■ Those models are inspired by neural activations

(Smith, Ratcliff, 2004)


Stochastic accumulation models

■ General concepts◻ Sensory evidence of a stimulus accumulates over time◻ Multiple competed information accrue in parallel◻ A decision is made according accumulated evidence

■ Simple response: signal detection■ Choice responses: choice among several possible outcomes

■ Models usually concern three major aspects:◻ How is decision information being accumulated?◻ When to stop?◻ What is the basis for making a decision?


Diffusion model

■ Diffusion model is a continuous version of accumulator model.◻ Simple Response

Model for simple and Go/NoGo RT. The time-dependent information function u(t) is perturbed by white noise W(t) and accumulated. A response is emitted when the accumulated decision stage activation X(t) exceeds a criterion.

(smith, 2000)


Diffusion model

◻ Two-choice Response

Smith, 2000

Beyond reaction time: Speed accuracy trade-off (SAT)■ RTs typically co-vary with error rates■ Speed-accuracy trade-off function

◻ Fixed accuracy, measuring RTs (fair comparison across conditions)


Next week

■ Hands-on RT analyses◻ Import RT data from a behavioral study◻ Summarize RT data◻ Visualize results

■ Requirement◻ Please make sure your R and Rstudio work◻ tidyverse package is installed

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mental chronometry - uni-muenchen.de · 2018. 11. 6. · c1 c2 + p1 p2 c1 c2 p1 p2. 20 zhuanghua...

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