LA RETROALIMENTACIÓN NEGATIVA COMO MECANISMO A LA BASE DEL CAMBIO DE PREPARACIÓN MENTAL AL...

LA RETROALIMENTACIÓN NEGATIVA COMO MECANISMO A LA BASE DEL CAMBIO DE

PREPARACIÓN MENTAL AL ALTERNAR ENTRE DOS TAREAS DE MANERA REGULAR

Antonio González Hernández

DEPARTAMENTO DE PSICOLOGÍA EXPERIMENTAL Y FISIOLOGÍA DEL COMPORTAMIENTO

UNIVERSIDAD DE GRANADA

Director: Dr. Emilio Gómez Milán

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INDEX

• INTRODUCTION & HYPOTHESIS.– What is residual switch cost and how can we

measure it?

• THE STIMULUS AS THE KEY.– Experiments 1 & 2.– Experiments 3 & 4.

• THE RESPONSE AS THE KEY.– Experiments 5, 6 & 7.

• CONCLUSIONS.

Introduction• What is switch cost?

– Transient impairment in performance (decrease in accuracy or increased RT).

– Jersild (1927)- “shift loss”.– Spector and Biederman (1976).– Allport, Styles & Hsieh (1994)- task set inertia.– Indexes the duration of a control process that

accomplishes task-set reconfiguration.– Rogers & Monsell (1995)- Two components.

Two components in task switching• Non-residual component.

– Can be eliminated by an active (endogenous) process of preparation.

• Residual component.– Can not be eliminated by an anticipation

process.– Disappears after first repetition trial (under

predictable conditions).– An exogenous reconfiguration process makes it

disappear.– Represents a cognitive limitation.

Hypothesis• Mental inertia (Allport et al, 1994).

– Pro-active interference from a recently adopted task-set.

– Cost asymmetry: larger cost when one switches from a non-dominant task to a dominant one. Non-dominant tasks result in a stronger set.

• Micropractice (Meiran, 1996).– Retroactive adjustment.

– Gradual decrease not detected in R & M (1995).- predictable switch causes preparation for the next task, which slows the response on repetition trials.

• Stimulus cued completion hypothesis.

The stimulus cued completion hypothesis (Rogers & Monsell, 1995)

• Residual cost is associated to the appearance of a stimulus related to the new task.

• The appearance of the target would trigger the exogenous reconfiguration process.

How can we measure residual cost?

– Predictable conditions

• Task switched every three trials.

• Fixation point was informative about the following task (@-#).

• Long RSI (1200 ms.).

– The tasks:• Letter task: is the letter a vowel or a consonant?

• Number task: is the number odd or even?

@ or #(1200 ms)

1A B4 C2 E3

(500 ms)

RESPONSE

(“b” or “n” in the keyboard)

(2500 ms)

(Sound feedback for errors and no response)

Results under predictable conditions

• There is a switch cost.

• Cost disappears with first repetition trials.

Figure 1 (from Tornay & Milán, 2001)

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0 1 2Number of Repetitions

RT

(m

s)

Predictableswitch

Research goals• To verify the disappearance of residual cost after

the first repetition trial.• To determine the real nature of this residual

component.– Is the stimulus the key to complete reconfiguration?

– Is it the response?

– Are both?

• For these goals we have created new conditions:– Stimulus without response.

– Response without stimulus.

INDEX


measure it?



• CONCLUSIONS.

Experiment 1- Goals

• To verify the role played by the stimulus in mental set reconfiguration.

Experiment 1- Design• Participants: Twelve undergraduates.

• Variables:– Condition: Go or No-Go (go-signal in switch

trials). Go-signal before the stimulus (50%).– Congruency: congruent and incongruent trials.– Task: letter task and number task.– Repetition: switch trials; first repetition trials;

second repetition trials.

• Dependent Variables: RT and accuracy.

SWITCH TRIALS

FIRST REPETITION

TRIALS

SECOND REPETITION

TRIALS

NO-GO CONDITION

NO RESPONSE RESPONSE RESPONSE

GO CONDITION

RESPONSE RESPONSE RESPONSE

Experiment 1- Design

Experiment 1- Hypothesis

• If attention to the stimulus completes reconfiguration no cost would appear in no-go condition ( )

• If the stimulus is not the key, we will observe a cost displacement (---).

Hypothetical results

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1 2 3Number of repetitions

RT

(m

s)

No-Go

Go

No-Go

Experiment 1- Results

• There is a cost displacement from switch trials to first repetition trial.

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Number of Repetitions

Reac

tion

Tim

e (m

s)

Go

No-Go

Experiment 1- Conclusions• With the go-condition we replicate results

using predictable sequences.– Cost disappears with first repetition trials.

• With the no-go condition we observe that paying attention to the stimulus does not eliminate cost.– We can observe cost even with a more than five

seconds of foreknowledge period.

Experiment 2- Goals

• To ensure attention in no-go condition.

• To verify the role played by the stimulus in mental set reconfiguration.– Differences with experiment 1:

• The go-signal appears 500 ms. after the target.

• The go-signal was manipulated on a trial by trial basis.

Experiment 2- Design• Participants: Ten undergraduates.• Variables:

– Condition: Go or No-Go (Go-signal in switch trials). The go-signal appeared 500 ms after the target (50%).

– Congruency: congruent and incongruent trials.– Task: letter task and number task.– Repetition: switch trials; first repetition trials;



SWITCH TRIALS

FIRST REPETITION

TRIALS

SECOND REPETITION

TRIALS

NO-GO CONDITION

NO RESPONSE RESPONSE RESPONSE

GO CONDITION

RESPONSE RESPONSE RESPONSE



• In this case we ensure the attention to the stimulus.

• If this is sufficient, no cost will be observed in no-go condition ( ).

• If it is not, a cost displacement will appear (---).


550600650700750800850

1 2 3Number of repetitions

RT (m

s)

No-GoGoNo-Go


• Results are similar to those found in experiment 1.

• We found again a cost displacement.

• Attention to the stimulus and response programming are not enough to complete reconfiguration.

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0 1 2


Reac

tion T

ime (

ms)

Go

No-Go

Experiment 2- Conclusions• The general improvement in RT and

accuracy indexes to the response preparation.

• There is a cost displacement from switch trials to first repetition trials.

• In the “Go” Condition, we observed a similar pattern of results to that found in “Go” Condition of experiment 1.

Experiment 3- Goals• To eliminate sequential effects due to the

go-nogo manipulation.

• To verify the role played by the stimulus in mental set reconfiguration. – Differences with the previous experiments:

• There were also no-go repetition trials.

• To verify Schuch & Koch hypothesis:– Predicts residual cost if response selection

occurs.

Experiment 3- Design• Participants: Ten undergraduates.• Variables:

– Condition: Go signal in trial n-1: Go or No-Go. In this experiment the go-signal “No” could appear in every trial. 50%.




SWITCH TRIALS

FIRST REPETITION

TRIALS

SECOND REPETITION

TRIALS

NO-GO CONDITION

NO RESPONSE IN PREVIOUS

TRIAL


TRIAL


TRIAL

GO CONDITION

RESPONSE IN PREVIOUS

TRIAL


TRIAL


TRIAL



• There are also no-go repetition trials in order to avoid sequential effects produced by the go-signal manipulation.

• Following Schuch & Koch hypothesis there must not be cost in No-Go condition.


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0 1 2


RT (m

s)

No-Go Go


• In the Go-condition the pattern of results was consistent with the normal residual cost found under predictable conditions.

• In the No-Go condition there seems to be no cost, as reported Schuch and Koch (2003).

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0 1 2


Reac

tion

Tim

e (m

s) Go

No-Go

Experiment 3- Conclusions

• The slower RTs found for No-Go condition could be due to sequential effects.

• These results could be explained as a no cost or as a no repetition benefit.

Experiment 4- Goals

• To ensure response preparation increasing the go-signal’s validity (80%).

• To verify the role played by the stimulus in mental set reconfiguration.

• To verify Schuch & Koch’s hypothesis.

• Differences with experiment 3:– There is a higher go-signal’s validity.

Experiment 4- Design• Participants: Eight undergraduates.• Variables:

– Condition: Go signal in trial n-1: Go or No-Go. In this experiment the go-signal “No” could appear in every trial. 80%.




SWITCH TRIALS

FIRST REPETITION

TRIALS

SECOND REPETITION

TRIALS

NO-GO CONDITION


TRIAL


TRIAL


TRIAL

GO CONDITION


TRIAL


TRIAL


TRIAL



• The go-signal’s validity is higher (80%) so expected response selection.

• Following Schuch & Koch hypothesis, there will be residual cost in No-go condition.


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850

0 1 2


RT (m

s)

No-Go Go


• Again we replicated residual cost in the Go-condition.

• In the No-Go condition there is a cost displacement from switch trials to first repetition trials. 550

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0 1 2


Rea

ctio

n Ti

me

(ms)

Go

No-Go

Experiment 4- Conclusions.• The Go-Signal validity is important.

• Residual cost was still apparent in the first repetition trials in No-Go condition.

• Response selection seems to be the key factor to produce the residual cost: (no residual cost in No-Go condition Experiment 3 (Go-Signal validity=50%) vs significant residual cost in No-Go condition Experiment 4 (Go-Signal=80%).

• It seems clear that what triggers exogenous reconfiguration process is not stimulus-related.

• Response selection seems to be the key factor to produce residual cost.

Conclusions from experiments 1-4

INDEX


measure it?



• CONCLUSIONS.

Experiment 5- Goals

• To verify the response’s role in mental set reconfiguration.

• For this aim we created a new condition where a response was executed in the absence of the target.

Experiment 5- Design• Participants: twelve undergraduates.

• Variables:– Condition: Response in ITI (space bar); No

response in ITI. – Congruency: congruent and incongruent trials.– Task: letter task and number task.– Repetition: switch trials; first repetition trials;



SWITCH TRIALS

FIRST REPETITION

TRIALS

SECOND REPETITION

TRIALS

NO RESPONSE

CONDITION


ITI


ITI1


ITI

RESPONSE CONDITION

RESPONSE IN PREVIOUS ITI





• If any response (in the absence of the target) completes the reconfiguration, no cost must appear in response in ITI condition.


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900

0 1 2


RT (m

s)

No response in ITI

Response in ITI


• Again we replicate residual component in No response condition.

• No effect of response in ITI was observed.

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Rea

ctio

n Ti

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(ms)

Response in ITI

No Response in ITI

Experiment 5- Conclusions• Any single unrelated response does not

trigger the mechanism of mental set reconfiguration to switch from a task to a new one without cost.

• With the results obtained we can not conclude that motor responses are not important to complete the reconfiguration.

• In the next experiment we will observe what happens with residual cost if the response to execute during the ITI is a related one.

Experiment 6- Goals


• For achieve this aim we modified the response to execute during ITI.


• Variables:– Condition: Response in ITI (“b” key or the “n”

key); No response in ITI. – Congruency: congruent and incongruent trials.– Task: letter task and number task.– Repetition: switch trials; first repetition trials;



SWITCH TRIALS

FIRST REPETITION

TRIALS

SECOND REPETITION

TRIALS

NO RESPONSE

CONDITION


ITI


ITI1


ITI

RESPONSE CONDITION






• If this response (in the absence of the target) completes the reconfiguration, no cost must appear in response in ITI condition.


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650

700

750

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850

900

0 1 2


RT (m

s)

No response in ITI

Response in ITI


• Again we replicate residual cost in No response condition.

• Response in ITI seems to eliminate residual cost.

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750

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850

900

0 1 2


Reac

tion

Tim

e (m

s)

Response in ITI

No Response in ITI

Experiment 6- Conclusions• These intermediate associated responses

eliminate the residual cost: participants’ execution in switch trials is as good as in repetition trials.

• The execution in all the trials in the response in ITI condition behave like repetition trials.

• In the next experiment we will see what happens with a choice extra task and unrelated responses.

Experiment 7- Goals


• For achieve this aim, in this experiment the response was not related with the alternating tasks.


• Variables:– Condition: Response in ITI (the “R” key or the

“O” key); No response in ITI. – Congruency: congruent and incongruent trials.– Task: letter task and number task.– Repetition: switch trials; first repetition trials;



SWITCH TRIALS

FIRST REPETITION

TRIALS

SECOND REPETITION

TRIALS

NO RESPONSE

CONDITION


ITI


ITI1


ITI

RESPONSE CONDITION






• If this choice response (in the absence of the target) completes the reconfiguration, no cost must appear in response in ITI condition.


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650

700

750

800

850

900

0 1 2


RT (m

s)

No response in ITI

Response in ITI


• Again we replicate residual component in No response in ITI condition.

• Response in ITI seems to eliminate residual cost.

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850

900

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Rea

ctio

n Ti

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(ms)

Response in ITI

No Response in ITI

Experiment 7- Conclusions.• These intermediate non-associated

responses eliminate the residual cost: participants’ execution in switch trials is as good (or even better) as in repetition trials.

• An irrelevant interpolated task can be used to abolish residual cost.

• Therefore it seems that it is a choice task what triggers the reconfiguration mechanism (even in the absence of target).

INDEX


measure it?



• CONCLUSIONS.

General Conclusions-I

• The residual switch cost seems to be a very robust effect with predictable sequences; it seems to be a real cognitive limitation (we have replicated it in all our experiments).

• It seems clear that what triggers exogenous reconfiguration process is not stimulus-related.

• Response selection seems to be the key factor to produce residual cost.

General Conclusions-II• The execution of a choice response (even in

the absence of the target) seems to complete the mental set reconfiguration process, and consequently, eliminate residual cost.

• This response must not be necessarily related with the task.

• A choice response, where some kind of uncertainty is elicited, completes the reconfiguration.

General Conclusions-III• Residual cost shows a cognitive limitation that

forces us to make a mistake (or to prevent to make a mistake) before our mental set is reconfigured.

• Our results are against the stimulus cued completion hypothesis and in favor of a cognitive “reset button” in the brain (activation of S-R decision rules and response execution).

• There seems to be a negative feed-back mechanism that completes the mental reconfiguration necessary to execute the new task in a suitable way.

General Conclusions-IV

• Only a retroactive adjustment after a response execution makes residual cost disappear.

• Our system is able to activate this negative feed-back mechanism by means of the execution of a choice response even in the absence of the target.

Muchas gracias por su atención

Thank you

Antonio González- [email protected]

LA RETROALIMENTACIÓN NEGATIVA COMO MECANISMO A LA BASE DEL CAMBIO DE PREPARACIÓN

MENTAL AL ALTERNAR ENTRE DOS TAREAS DE MANERA REGULAR

mailto:[email protected]

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