9-2-08StroopEffectIntroduction

7/29/2019 9-2-08StroopEffectIntroduction

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Stroop Effect


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Brief Outline of the Introduction

Define Interference Describe Stroop (as a task to measure interference)

Exp 1-little interference

Exp 2-lots of interference

Interference is funny

Relative Speed of processing as an explanation for theinterference seen in the Stroop effect (more details here)

Point out predicts fast read will interfere with slow color-naming, but the exact word does not matter

Study where type of word does matter Final Paragraph


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Stroops First Experiment

Task: Read Words

Control

Red

Blue

Green

Brown

Purple

Incongruent

Red

Blue

Green

Brown

Purple


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Stroops Second Experiment

Task: Name Colors

Control Incongruent

Red

Blue

Green

Brown

Purple


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Variants on the Stroop Effect

Words above, below, left or right of a dot

Name typefaces bold, italics, underline

Sorting Tasks

Picture naming tasks

Stroop Effect of words that differ from color

words in one letter onlyPitch reporting


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Explanations for the Stroop Effect

Physiologically


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Automaticity Theory

All skills are learned to some degree of

automaticity.

More automatic skills require less attentional

resources.

The processing of the color dimension requires

much more attention than does processing of

the reading dimension.


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Perceptual Encoding Theory

Interference during encoding.

The perceptual encoding of the ink color isslowed by incompatible information from the

incongruent color word.


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Relative Speed of Processing Theory

Interference during response selection.

The two dimensions of the stimulus are processed inparallel.

There is a limited capacity response channel intowhich only one of the two potential responses can beadmitted, priority is determined by speed.

Each possible response comes through at a differentspeed.

The two responses compete to be the responseactually produced.

The two codes for the two responses are seen asracing to control the final output.

The time cost of this competition is interference.


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Is the Stroop Effect caused by Interference?

The presence of the words interferes with the

naming of the colors (or pictures or shapes).However, the Stroop effect doesnt work in

reverse

Words strongly related semantically to color(such as blood or sky) cause moreinterference than unrelated words.

Words high in emotional content produce

more interference.


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Our Experiment

Research Question

The relative speed of processing theory

beautifully predicts the interference of (very

fast) reading on our ability to perform a lesswell-learned (slower) skill. However, the theory

does not predict that any one word is more

interfering than another. We will test whether,contrary to the relative speed of processing

theory, the semantic relatedness of the

interfering words matters.


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Our Experiment

Hypotheses

The relative speed of processing theory falls short ofadequately explaining the interference in a Stroop-liketask.

Changing the cognitive meaning of the interferingword will change the amount of interference the wordwill create.

Words belonging to the same semantic category asthe task to be named will create more interferencethan words belonging to an unrelated semanticcategory.


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Our Experiment

Possible Stimuli

Control

Square Triangle

Circle Rectangle

Diamond

Incongruent

Semantically Related

Square with circle

Triangle with diamond

Circle with rectangle

Rectangle with square

Diamond with triangle

Incongruent Semantically

Unrelated

Square with flower

Triangle with 7 letter word

Circle with 9 letter word

Rectangle with 6 letter word

Diamond with 8 letter word


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If the relative speed of processing explains the

Stroop effect, what do the stimuli mean?

Control = Time needed to name shapes; a puremeasure of shape naming skills.

ISR - Control = The interference that the presence ofsemantically related words has on shape naming

skills; a reflection of Stroops second experiment. ISU - Control = The interference that the presence of

semantically unrelated words has on shape namingskills; perhaps a true measure of the interferencedescribed by the relative speed of processing theory.

ISR - ISU = Extent to which interference fromsemantically related words is stronger thaninterference from semantically unrelated words; if thisnumber is anything other than zero, it is the amount to

which the relative speed of processing theory fallsshort of predicting interference.


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Our Experiment

Predictions

Control vs. ISR (Basic Stroop Effect)Control will be faster than ISR

Control will have fewer errors than ISR

Control vs. ISUControl will be faster than ISU

Control will have fewer errors than ISU

ISR vs. ISU (Degree to which RSP falls short)ISR will take longer than ISU

ISR will have more errors than ISU


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Our Experiment

Internal Validity Issues

Must present all three lists to the same peoplebecause high amounts of individual variabilitynecessitate that people act as controls for themselves.

After naming shapes for a while, people will get betterat the task. Therefore, we can not present the lists inthe same order every time.

If we only look at six responses from each condition,

then a single bad response could drastically increaseaverage time.

How many total trials should be used for an entireexperiment?

We need multiples of 15


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Our Experiment


If all lists present the shapes in the same order,

people will remember the order.

If we always present control in one order, then

always present pictures in a second, then there

could be something about one of the orderings

that may be more memorable than another.

Perhaps we should include practice trials that

do not count.


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Our Experiment


What about the stimuli?Should items in words list and pictures list be the

same?

Should we worry about the frequency of the words?

The word circle is common, the word flower is notreally common.

Should all words contain the same number of letters?circle = 6, flower = 6

Random presentation of stimuli?Make a really big list and randomly present from it?

Create blocks? Maybe Part 1 and Part 2 ofexperiment so we can use a repeated measuresfactor to experimentally account for picture naming

learning.

Documents

9-2-08StroopEffectIntroduction