2 nd Year Practicals November 2008 Dr Jonathan Stirk [email protected] Room C44 Office Hours: Wednesdays 10-11am Demonstrator: Maria Ktori.

22ndnd Year Practicals Year PracticalsNovember 2008November 2008

Dr Jonathan StirkDr Jonathan [email protected]

Room C44Room C44Office Hours: Wednesdays 10-11amOffice Hours: Wednesdays 10-11am

Demonstrator: Maria KtoriDemonstrator: Maria KtoriContact by e-mail: [email protected] by e-mail: [email protected]

Room: A24Room: A24Office hour: Mondays 2pmOffice hour: Mondays 2pm

Selective Attention & the Selective Attention & the Flanker Compatibility Effect Flanker Compatibility Effect (FCE)(FCE)• Structure of Structure of

practicalpractical– 5 week structure5 week structure

Week 1Week 1 Mini-lecture, example exp’ts, literature Mini-lecture, example exp’ts, literature searchsearch

Week 2Week 2 Develop hypothesis, select projectDevelop hypothesis, select project

Week 3Week 3 Pilot study, collect dataPilot study, collect data

Week 4Week 4 Data analysis (Mini-lecture)Data analysis (Mini-lecture)

Week 5Week 5 PresentationsPresentations

Week 6Week 6 Hand in written report (Hand in written report (DeadlineDeadline Monday Monday 88thth December, 2008 by 4pm.) December, 2008 by 4pm.)

Aims of this practicalAims of this practical

• To learn about the flanker compatibility To learn about the flanker compatibility effecteffect

• To design an experiment to test a To design an experiment to test a specific hypothesis about flanker effectsspecific hypothesis about flanker effects

• To learn to implement a design using E-To learn to implement a design using E-Prime softwarePrime software

• To learn to collect and analyze data To learn to collect and analyze data using computer software (E-Prime, using computer software (E-Prime, SPSS)SPSS)

What is attention?What is attention?

• ‘‘Attention is the process of Attention is the process of concentrating on specific features of concentrating on specific features of the environment, or on certain the environment, or on certain thoughts or activities. This focusing on thoughts or activities. This focusing on specific features of the environment specific features of the environment usually leads to the usually leads to the exclusionexclusion of other of other features of the environment ‘.features of the environment ‘.

Colman (2001)Colman (2001)

What is selective attention?What is selective attention?

• 2 main types of attentional tasks2 main types of attentional tasks– Divided attention tasks (dual tasks)Divided attention tasks (dual tasks)

•Paying attention equally to more than one thingPaying attention equally to more than one thing– E.g. Reading out loud a story , whilst writing down E.g. Reading out loud a story , whilst writing down

dictated words (Spelke, Hurst & Neisser, 1976), dictated words (Spelke, Hurst & Neisser, 1976), driving whilst listening for a specific news item on the driving whilst listening for a specific news item on the radio.radio.

– Selective attention tasksSelective attention tasks•Paying attention to one source of information Paying attention to one source of information

whilst ignoring everything elsewhilst ignoring everything else– E.g. Identifying words presented to the left ear, whilst E.g. Identifying words presented to the left ear, whilst

ignoring words presented to the right ear in a dichotic ignoring words presented to the right ear in a dichotic listening task (Cherry, 1953)listening task (Cherry, 1953)

Models of selective Models of selective attentionattention• Where within the flow of information does Where within the flow of information does

specific information become selected and specific information become selected and other information dismissed? i.e. When other information dismissed? i.e. When does selection take place?does selection take place?

• Does selection occur early in processing Does selection occur early in processing or later on?or later on?

Sensory Store ResponseSTIMULI

Further processing

Sensory Store ResponseSTIMULI

Further processing

EarlyEarly versus late models of versus late models of selective attentionselective attention

• Early-selection modelsEarly-selection models assume that assume that selection occurs early-on in processing selection occurs early-on in processing [after analysis of physical [after analysis of physical characteristics/features e.g. Broadbent characteristics/features e.g. Broadbent (1958)]. From this point on unattended (1958)]. From this point on unattended information receives little or no further information receives little or no further processing.processing.

• So NO semantic (identification) processing So NO semantic (identification) processing of the ignored/unattended information.of the ignored/unattended information.

Early versus Early versus latelate models of models of selective attentionselective attention

• Late-selection modelsLate-selection models propose that ALL propose that ALL stimuli are analysed up to the point of stimuli are analysed up to the point of identification (to a semantic level) and identification (to a semantic level) and selection occurs after this point, i.e. later selection occurs after this point, i.e. later on in the processing stream.on in the processing stream.

• So to-be-ignored stimuli receive So to-be-ignored stimuli receive considerable processing and selection considerable processing and selection occurs much closer to the response end.occurs much closer to the response end.

Early and late selectionEarly and late selection

Physical characteristics

Meaning

All messages in

Selected message

Selected message

BIG questions!BIG questions!

• Some questions in Some questions in attentional research attentional research are:are:

• ““To what extent are To what extent are irrelevant stimuli irrelevant stimuli processed in selective processed in selective visual attention visual attention tasks?”tasks?”

• ““How can we explain How can we explain what is and isn’t what is and isn’t selected?”selected?”

How can we examine the How can we examine the extent to which irrelevant extent to which irrelevant information is processed?information is processed?• Priming studiesPriming studies

– Do to-be-ignored stimuli prime future Do to-be-ignored stimuli prime future performance on a cognitive task?performance on a cognitive task?

• Flanker tasksFlanker tasks– Do surrounding irrelevant stimuli affect Do surrounding irrelevant stimuli affect

performance on target stimuli?performance on target stimuli?• Eriksen & Eriksen (1974): classic flanker effectEriksen & Eriksen (1974): classic flanker effect• A response competition paradigm (similar to Stroop!)A response competition paradigm (similar to Stroop!)• This is a selective visual attention taskThis is a selective visual attention task• It can also be used to examine ‘automatic’ processing It can also be used to examine ‘automatic’ processing

of stimuli (processing without attention)of stimuli (processing without attention)• Or… Capture of attention by irrelevant stimuliOr… Capture of attention by irrelevant stimuli

Eriksen & Hoffman (1973)Eriksen & Hoffman (1973)

• Original exp’t used Original exp’t used circular displayscircular displays of of letters and S’s had to identify the letters and S’s had to identify the presence of a target (out of 4 possible presence of a target (out of 4 possible targets) flanked by distracterstargets) flanked by distracters

H

H

AA

H

M

U M

U

U

M

U

The flanker compatibility The flanker compatibility effecteffect• Flankers are stimuli which are presented spatially Flankers are stimuli which are presented spatially

close to close to target stimulitarget stimuli and which should be and which should be ignoredignored

• Despite the irrelevance of flankers to the target Despite the irrelevance of flankers to the target task they are often shown to interfere with target task they are often shown to interfere with target responsesresponses

• The original task involved being presented with 5 The original task involved being presented with 5 letter strings and determining the identity of the letter strings and determining the identity of the middle letter by moving a lever to the left or rightmiddle letter by moving a lever to the left or right

• More modern versions involve left and right More modern versions involve left and right hands pressing specific buttons/keys to identify a hands pressing specific buttons/keys to identify a targettarget

Eriksen et al (1974): linear Eriksen et al (1974): linear display taskdisplay task

LEFT HAND RESPONSE

RIGHT HAND RESPONSE

Target:

H K S C

H H K H H

E.g. Respond left

S S C S SE.g. Respond right

flankers flankers

target

REVERSE MAPPINGS CAN BE USED TOO!

Compatibility of responsesCompatibility of responses

• However, the However, the compatibility compatibility of the target of the target and flanker and flanker responses is responses is importantimportant

• RT to target:RT to target:

Incompatible Incompatible trials > trials > Compatible Compatible trialstrials

Stimuli Compatibility Response hand

Target Flanker

HHKHH Compatible L K H

KKHKK Compatible L H K

SSCSS Compatible R C S

CCSCC Compatible R S C

SSKSS Incompatible L K S

CCKCC Incompatible L K C

CCHCC Incompatible L H C

SSHSS Incompatible L H S

HHCHH Incompatible R C H

KKCKK Incompatible R C K

HHSHH Incompatible R S H

KKSKK Incompatible R S K

Defining the flanker Defining the flanker compatibility effectcompatibility effect• The FCE is the difference in RT between the two The FCE is the difference in RT between the two

types of compatibility trialstypes of compatibility trials• FCE = Incompatible trials – compatible trialsFCE = Incompatible trials – compatible trials• E.g. 500 ms-420 ms FCE of 80msE.g. 500 ms-420 ms FCE of 80ms

• Sometimes the effect is measured with respect to a Sometimes the effect is measured with respect to a base-line conditionbase-line condition– One in which flankers are One in which flankers are NeutralNeutral with respect to target with respect to target

responsesresponses– E.g XXSXX (where the X flanker does not belong to the E.g XXSXX (where the X flanker does not belong to the

target set)target set)– RT differences can then be framed as “costs” or “benefits”RT differences can then be framed as “costs” or “benefits”

• i.e. we can examine facilitation and interferencei.e. we can examine facilitation and interference

What factors moderate the What factors moderate the FCE?FCE?• Research has shown that the FCE is quite Research has shown that the FCE is quite

robustrobust• However, a number of factors have been However, a number of factors have been

shown to moderate the effectshown to moderate the effect• Early research suggested that flanker-target Early research suggested that flanker-target

distancedistance was important was important– Eriksen & Eriksen (1974) showed that larger Eriksen & Eriksen (1974) showed that larger

spatial separation (eccentricity) reduced the FCEspatial separation (eccentricity) reduced the FCE– Distracters within 1Distracters within 1° of visual angle could not be ° of visual angle could not be

ignoredignored– Possible evidence for a ‘fixed-width spotlight’ of Possible evidence for a ‘fixed-width spotlight’ of

selective attention (Posner, 1980)selective attention (Posner, 1980)

Fixed-width spotlight Fixed-width spotlight metaphormetaphor

S C S

< 1 deg

Fixed width (2 deg)

Flankers cannot be ignored as they are within the space selected for attention

Fixed-width spotlight Fixed-width spotlight metaphormetaphor

S C S

> 1 deg

Fixed width (2 deg)

Flankers may now receive less processing

Explanations of separation Explanations of separation effectseffects

• The spotlight metaphor helps to explain the The spotlight metaphor helps to explain the effects of target-flanker separation on the effects of target-flanker separation on the FCE.FCE.

• However, other explanations are viableHowever, other explanations are viable– Visual acuity decreases the further objects are Visual acuity decreases the further objects are

from the point of fixationfrom the point of fixation• So perhaps increasing the size of flankers/targets is So perhaps increasing the size of flankers/targets is

important in controlling for acuity problemsimportant in controlling for acuity problems

– Distance is confounded by Gestalt groupingDistance is confounded by Gestalt grouping• The law of proximity suggests that closeness effects The law of proximity suggests that closeness effects

grouping of stimuligrouping of stimuli

Law of proximityLaw of proximity

Grouped by columnGrouped by column Grouped by rowGrouped by row

So does perceptual grouping So does perceptual grouping affect the FCE?affect the FCE?

• What if attention is to objects rather What if attention is to objects rather than space?than space?– If attention is object-based then If attention is object-based then

principles of grouping may affect what is principles of grouping may affect what is selected for further processingselected for further processing

– Driver & Baylis (1989) used ‘common Driver & Baylis (1989) used ‘common motion’ to compete the ‘distance’ vs motion’ to compete the ‘distance’ vs ‘grouping’ hypotheses‘grouping’ hypotheses

Driver & Baylis (1989)Driver & Baylis (1989)

T TH X H• The results showed that moving distant distracters

(e.g. the H’s above) produced more interference than the static closer distracters (e.g. the T’s above).

• So, perceptual grouping seems important in the allocation of attention and in the FCE

Further effects of groupingFurther effects of grouping

• Harms & Bundesen (1983)Harms & Bundesen (1983)– Used colour segregation of Used colour segregation of

targets/distracterstargets/distracters– E.g. (1) F T F versus (2) E.g. (1) F T F versus (2) FF T T FF– This encouraged colour segregation of This encouraged colour segregation of

targets/distracters in condition 2targets/distracters in condition 2– Smaller flanker compatibility effects in Smaller flanker compatibility effects in

condition 2condition 2

Further factors moderating Further factors moderating FCEFCE• Miller (1991) manipulated five factors to Miller (1991) manipulated five factors to

try and eliminate the FCE and determine try and eliminate the FCE and determine any boundary conditionsany boundary conditions1.1. Poor spatial resolutionPoor spatial resolution2.2. Inability to hold attentional focus on a fixed Inability to hold attentional focus on a fixed

locationlocation3.3. Inability to focus completely on an empty Inability to focus completely on an empty

display locationdisplay location4.4. Inability to filter out stimuli which onset at the Inability to filter out stimuli which onset at the

same time as the target during the tasksame time as the target during the task5.5. Inability to prevent analysis of Inability to prevent analysis of allall stimuli when stimuli when

there is insufficient demand by the attended there is insufficient demand by the attended itemsitems

Consistent & varied Consistent & varied mappingmapping• Miller hypothesised that we are unable to Miller hypothesised that we are unable to

maintain attention on a fixed location and maintain attention on a fixed location and this may be why attention leaks to the this may be why attention leaks to the irrelevant distractersirrelevant distracters

• In the linear task the target is always in In the linear task the target is always in the same spatial locationthe same spatial location

• So, he varied the locations of So, he varied the locations of targets/distracters and used a __ (bar) pre-targets/distracters and used a __ (bar) pre-cue to direct attention to the locationcue to direct attention to the location

• The FCE was The FCE was NOTNOT diminished when varied diminished when varied mapping was usedmapping was used

+

H

X X

Miller’s Boundary ConditionsMiller’s Boundary Conditions

• Perhaps it is not the constancy but Perhaps it is not the constancy but rather the emptiness of the attended rather the emptiness of the attended location which prevents early location which prevents early selection from fully excluding other selection from fully excluding other locations from further processinglocations from further processing

• Necessary object hypothesisNecessary object hypothesis• Miller used an RSVP version of the Miller used an RSVP version of the

flanker task to test thisflanker task to test this

RSVP taskRSVP task

• The necessary object hypothesis predicts an FCE only when the The necessary object hypothesis predicts an FCE only when the target appears in frame 1 (as there is no previous object in the target appears in frame 1 (as there is no previous object in the target location)target location)

• However, results showed that the FCE was present in later frames However, results showed that the FCE was present in later frames refuting the hypothesisrefuting the hypothesis

+

F T F

F Q F

F * F

F D F

F B F

TIME

F = flanker T = target

200ms

200ms

200ms

200ms

1

2

3

4

5

Miller’s Boundary ConditionsMiller’s Boundary Conditions

• Maybe we can’t filter out flankers Maybe we can’t filter out flankers because they onset at the same time as because they onset at the same time as the targetthe target– Yantis & Jonides (1984) had shown that Yantis & Jonides (1984) had shown that

abrupt onsets attract attention in a visual abrupt onsets attract attention in a visual tasktask

• Miller varied onset/offset transients of Miller varied onset/offset transients of flankers/targetsflankers/targets

• Used ‘figure 8’ concept.Used ‘figure 8’ concept.

Yantis & Jonides’ ‘figure 8’Yantis & Jonides’ ‘figure 8’

• Results showed that transients had Results showed that transients had nono effect on the effect on the FCEFCE

• Transients therefore do not seem to be responsible Transients therefore do not seem to be responsible for the partial leakage of unattended stimuli for the partial leakage of unattended stimuli through an early selection mechanism.through an early selection mechanism.

+

Fixation Pre-mask 500ms

Target screen (all offsets in this example

Miller’s Boundary ConditionsMiller’s Boundary Conditions

• What if processing of the irrelevant What if processing of the irrelevant flankers is because attentional flankers is because attentional ‘capacity’ is underloaded leaving ‘capacity’ is underloaded leaving room for processing of the flankers?room for processing of the flankers?– Perceptual underload hypothesisPerceptual underload hypothesis

• So Miller varied the amount of So Miller varied the amount of relevant information and examined relevant information and examined the FCEthe FCE

Perceptual Underload Perceptual Underload StimuliStimuli

H G J

K D

B C L F F

Flankers

TARGET (attended)REGION

Number of letters varied

Perceptual Underload Perceptual Underload StimuliStimuli

• Results showed that the FCE was Results showed that the FCE was eliminated for the larger set sizeseliminated for the larger set sizes

• Finally a boundary condition for FCE?Finally a boundary condition for FCE?– NO as there was a confound of timingNO as there was a confound of timing

• Further experiments did NOT support Further experiments did NOT support the underload hypothesisthe underload hypothesis

So what are you going to So what are you going to do?do?• Get into small groups (3) and design Get into small groups (3) and design

an experiment to investigate a factor an experiment to investigate a factor which may effect the FCEwhich may effect the FCE

• Design needs to be at least a Design needs to be at least a 2 x 2 2 x 2 factorial designfactorial design– E.g. 2 IV’s!E.g. 2 IV’s!

•1. Compatibility of flankers (compatible vs. 1. Compatibility of flankers (compatible vs. incompatible)incompatible)

•22. Other variable of your own!. Other variable of your own!

Examples of factors to Examples of factors to manipulatemanipulate

• Any grouping factor e.g. Colour Any grouping factor e.g. Colour segregationsegregation– Harms & Bundesen (1983)Harms & Bundesen (1983)

• Number of flankers?Number of flankers?• Nature of flankers?Nature of flankers?

– Pictures vs. words?Pictures vs. words?

• Target-flanker separationTarget-flanker separation• E.t.c.E.t.c.

So for example… manipulate So for example… manipulate distancedistanceS,C left H,K right (response S,C left H,K right (response pairings)pairings)

CompatibleCompatible IncompatibleIncompatible

NearNearS C SS C S H C HH C H

FarFarS C SS C S H C HH C H

Leads to 4 conditions (cells) in the design, tested within-subjects

How are you going to do How are you going to do this?this?• Using E-Prime to control stimulus Using E-Prime to control stimulus

displaydisplay• Create stimuli materials in E-Prime or Create stimuli materials in E-Prime or

maybe using Paint or other graphics maybe using Paint or other graphics program (PowerPoint plus Paint)program (PowerPoint plus Paint)

• DEMO OF TEMPLATE (using letter DEMO OF TEMPLATE (using letter stimuli and manipulating target-flanker stimuli and manipulating target-flanker DISTANCE)DISTANCE)

So minimum number of trials is 32

Samples need to be weighted to balance out compatible/incompatible trials

What to do - recapWhat to do - recap

• So choose a further IV that you can So choose a further IV that you can manipulate at 2 levelsmanipulate at 2 levels– E.g. you may manipulate a grouping factor at 2 E.g. you may manipulate a grouping factor at 2

levelslevels– You might look at what type of information You might look at what type of information

(e.g. semantic?) can influence target response(e.g. semantic?) can influence target response

• Create stimuli for your experimentCreate stimuli for your experiment

• Program E-PrimeProgram E-Prime

• Run designRun design

Types of flanker tasks you can Types of flanker tasks you can useuse• Classic Letter flanker task S C SClassic Letter flanker task S C S• Colour flanker task Colour flanker task ** * * * * (Left- red/white, Right- Blue,green) (Left- red/white, Right- Blue,green)

respond to target colourrespond to target colour• Letter-number task 2 A 2 (classify target as either a letter or Letter-number task 2 A 2 (classify target as either a letter or

a number) a number) • Spatial/Arrows flanker task < < < vs. < > <Spatial/Arrows flanker task < < < vs. < > <• Semantic classification flanker taskSemantic classification flanker task

– Classify names as male/femaleClassify names as male/female• E.g. John Samantha John (incompat) vs. E.g. John Samantha John (incompat) vs. June Samantha June (compat)June Samantha June (compat)

– Classify target as large/small etc.Classify target as large/small etc.

• Remember this is essentially a response competition Remember this is essentially a response competition paradigm. If target responses are slowed then it must be paradigm. If target responses are slowed then it must be because of some flanker processing.because of some flanker processing.

Some ReferencesSome References

• Bindemann, M., Burton, A., & Jenkins, R. (2005). Capacity limits for face Bindemann, M., Burton, A., & Jenkins, R. (2005). Capacity limits for face processing. processing. Cognition, 98Cognition, 98(2), 177-197.(2), 177-197.

• Diedrichsen, J., Ivry, R.B., Cohen, A. & Danziger, S. (2000). Asymmetries in Diedrichsen, J., Ivry, R.B., Cohen, A. & Danziger, S. (2000). Asymmetries in a unilateral flanker task depend on the direction of the response: The role a unilateral flanker task depend on the direction of the response: The role of attentional shift and perceptual grouping. of attentional shift and perceptual grouping. Journal of Experimental Journal of Experimental Psychology: Human Perception and Performance, 26Psychology: Human Perception and Performance, 26, 113-126., 113-126.

• Driver, J. & Baylis, G.C. (1989). Movement and visual attention: the Driver, J. & Baylis, G.C. (1989). Movement and visual attention: the spotlight metaphor breaks down. spotlight metaphor breaks down. Journal of Experimental Psychology: Journal of Experimental Psychology: Human Perception & PerformanceHuman Perception & Performance, 15(3), 448-456., 15(3), 448-456.

• Eriksen, B. A., & Eriksen, C. W. (1974). Effects of noise letters upon the Eriksen, B. A., & Eriksen, C. W. (1974). Effects of noise letters upon the identification of a target letter in a nonsearch task. identification of a target letter in a nonsearch task. Perception & Perception & PsychophysicsPsychophysics, 16, 143-149., 16, 143-149.

• Eriksen, C.W. (1995). The flankers task and response competition: a useful Eriksen, C.W. (1995). The flankers task and response competition: a useful tool for investigating a variety of cognitive problems. tool for investigating a variety of cognitive problems. Visual CognitionVisual Cognition, 2, , 2, 101-118. (available as a .pdf from me)101-118. (available as a .pdf from me)

• Harms, L & Bundesen, C. (1983). Color segregation and selective attention Harms, L & Bundesen, C. (1983). Color segregation and selective attention in a nonsearch task. in a nonsearch task. Perception & PsychophysicsPerception & Psychophysics, 33, 11-19., 33, 11-19.

Some ReferencesSome References

• Miller, J. (1991). The flanker compatibility effect as a function of visual Miller, J. (1991). The flanker compatibility effect as a function of visual angle, attentional focus, visual transients, and perceptual load: a search for angle, attentional focus, visual transients, and perceptual load: a search for boundary conditions. boundary conditions. Perception & PsychophysicsPerception & Psychophysics, 49 (3), 270-288., 49 (3), 270-288.

• Shomstein, S. & Yantis, S. (2002). Object-based attention: sensory Shomstein, S. & Yantis, S. (2002). Object-based attention: sensory modulation or priority setting? modulation or priority setting? Perception & Psychophysics, 64Perception & Psychophysics, 64(1), 41-51.(1), 41-51.

• Styles, E. (1997). Styles, E. (1997). The psychology of attentionThe psychology of attention. UK: Psychology Press . UK: Psychology Press [Chapter 3][Chapter 3]

• Jenkins, R., Lavie, N. & Driver, J. (2003). Ignoring famous faces: category-Jenkins, R., Lavie, N. & Driver, J. (2003). Ignoring famous faces: category-specific dilution of distractor interference. specific dilution of distractor interference. Perception and Psychophysics, Perception and Psychophysics, 6565(2), 298-309.(2), 298-309.

• Lachter, J., Forster, K. I., & Ruthruff, E. (2004). Forty-five years after Lachter, J., Forster, K. I., & Ruthruff, E. (2004). Forty-five years after Broadbent (1958): Still no identification without attention. Broadbent (1958): Still no identification without attention. Psychological Psychological Review, 111Review, 111(4), 880-913.(4), 880-913.