Stroop Effect
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CONTENT CALENDAR 1. Tuesday 6 March: Intro & Basic Foundations 2. Thursday 8 March: Run an Experiment, Designing Computerized Experiments & Methods in Papers 3. Tuesday13 March: Classic Experiment 1: Attention & Interference 4. Thursday15 March: Classic Experiment 2: Spatial Attention 5. Tuesday 20 March: Classic Experiment 3: Divided & Selective Attention 6. Thursday 22 March: Experimental Design Proposal 7. Tuesday 27 March: Classic Experiment 4: Memory & Response Inhibition 8. Thursday 5 April: Classic Experiment 5: Embodiment & Sense of Self 9. Tuesday10 April: 14.30-18.30. Kinematic Data Acquisition 10. Thursday12 April: Summary & Test 1 EXPERIMENTAL DESIGN PROPOSAL . Small groups of 4/5 people (for 5/6 groups in total) . Select one or more relevant recent papers you’d like to focus on . Upload the paper(s) on e-learning . Try to review with a critical attitude the method . Design an original experiment (theoretical impact not essential) . Describe and list all the relevant variables, the timeline and the general procedure . Prepare a (visual) PowerPoint presentation . Present your own experiment in 10/15 minutes maximum (each person of the group should present an equal part), plus discussion from all the class group 2 THE XXXXXX EFFECT MEASURING ATTENTION & INTERFERENCE LESSON 3 LAB: COGNITIVE AND BEHAVIORAL MEASURES Luca Rinaldi 3 THE XXXXXX EFFECT • He received a PhD in experimental psychology from George Peabody College in 1932. • His dissertation, published in The American Journal of Experimental Psychology in 1935, focused on studies in interference and attention. • This study developed into a test that has since become foundational for the field of cognitive psychology. John Ridley Stroop 4 THE STROOP EFFECT 6 THE STROOP EFFECT A page from Stroop’s original materials for his experiments 7 THE STROOP EFFECT Stroop did not just use words to test his hypothesis; he also used shapes like these to see if the same interference appeared in both cases 8 THE STROOP EFFECT In its basic form, the task is to name the color in which a word is printed, ignoring the word itself: Name and color correspond RED GREEN BLUE PINK ORANGE BLUE GREEN WHITE GREEN YELLOW ORANGE WHITE BROWN RED BLUE GREEN PINK YELLOW GREEN RED 9 THE STROOP EFFECT In its basic form, the task is to name the color in which a word is printed, ignoring the word itself: Name and color do not correspond (1) RED GREEN BLUE PINK ORANGE BLUE GREEN WHITE GREEN YELLOW ORANGE WHITE BROWN RED BLUE GREEN PINK YELLOW GREEN RED 10 THE STROOP EFFECT In its basic form, the task is to name the color in which a word is printed, ignoring the word itself: Name and color do not correspond (2) TOWN CUP BELT PEN SCARF BELT CUP CLOCK CUP APPLE SCARF CLOCK SHOES TOWN BELT CUP PEN APPLE CUP TOWN 11 DIFFERENT CONDITIONS Which is the pattern of RTs you would guess on? Correspond Not correspond (1) Not correspond (2) RED RED TOWN ORANGE ORANGE SCARF GREEN GREEN CUP BROWN BROWN SHOES PINK PINK PEN 11 DIFFERENT CONDITIONS Which is the pattern of RTs you would guess on? Congruent Incongruent Neutral Neutral (2) RED RED TOWN ORANGE ORANGE SCARF GREEN GREEN CUP BROWN BROWN SHOES PINK PINK PEN 12 PATTERN OF RTS Which is the pattern of RTs you would guess on? ) ms ( RTs 400 600 800 1000 Incongruent Neutral Congruent Duncan-Johnson & Kopell, 1981 13 PERFORMANCE COST The performance cost in the mismatch condition – usually referred to as the incongruent condition – relative to the controls is called the Stroop effect or Stroop interference measure the interference of one stimulus dimension on another. 14 PERFORMANCE COST How would you actually compute cognitive interference? What is essential and what’s not? 15 PERFORMANCE COST How would you actually compute cognitive interference? What is essential and what’s not? PD Controls ) ms ( RTs 400 600 800 1000 Incongruent Henik, 1996 16 PERFORMANCE COST From Lesson 2 17 PERFORMANCE COST How would you actually compute cognitive interference? What is essential and what’s not? PD Controls ) ) ms ms ( Delta ( Delta RTs 400 600 800 1000 50 100 150 200 Incongruent Neutral Delta Henik, 1996 18 PERFORMANCE COST How would you actually compute cognitive interference? What is essential and what’s not? PD Controls ) ms Which kind of analysis would you actually carry ( on? RTs 400 600 800 1000 Incongruent Neutral Henik, 1996 19 PERFORMANCE COST How would you actually compute cognitive interference? What is essential and what’s not? PD 2x2 Mixed ANOVA: Controls Group (PD, Controls) x Condition (Neutral, Incongruent) Henik, 1996 20 PERFORMANCE COST How would you actually compute cognitive interference? What is essential and what’s not? PD 2x2 Mixed ANOVA: Controls Group (PD, Controls) x Condition (Neutral, Incongruent) Main effect of Group and Condition No significant Interaction Not significant Henik, 1996 21 PERFORMANCE COST How would you actually compute cognitive interference? What is essential and what’s not? Interference is the difference between the incongruent condition and the neutral condition (or congruent one) Interference = Incongruent – Neutral (Congruent) 22 STANDARD PROCEDURE An intriguing feature of the Stroop literature, though, is that there was virtually no follow-up to his work for about 30 years It is only in the 1960s that research on this phenomenon resumed and then with a vengeance The simplest explanation of this is that the advent of computer-controlled experiments, and especially the resulting ability to time individual trial stimuli, opened up a rich new realm of investigation for which the Stroop task was ideally suited 23 STANDARD PROCEDURE Trial by trial presentation, with RTs for each stimulus 500 ms + Until response BLUE (max 2000 ms) 24 EXPLANATION Do you have any idea of why interference is occurring? Speed of Processing Theory Selective Attention Theory 25 SPEED OF PROCESSING THEORY . Faster processes can affect slower processes . Slower processes cannot affect faster processes if the wrong dimension of a stimulus is processed prior to the right dimension (where right and wrong are denned by task demands), interference will result 26 SPEED OF PROCESSING THEORY . Faster processes can affect slower processes . Slower processes cannot affect faster processes From Lesson 1 27 SPEED OF PROCESSING THEORY . Faster processes can affect slower processes . Slower processes cannot affect faster processes RED 28 SPEED OF PROCESSING THEORY . Faster processes can affect slower processes . Slower processes cannot affect faster processes RED RED 29 SPEED OF PROCESSING THEORY . Faster processes can affect slower processes . Slower processes cannot affect faster processes How would you demonstrate this? 30 SPEED OF PROCESSING THEORY . Faster processes can affect slower processes . Slower processes cannot affect faster processes By asking participants to read words (and not name the ink)! From Stroop’s original experiment 31 PATTERN OF RTS Which is the pattern of RTs you would guess on? Color naming ) ms ( RTs 400 600 800 1000 Incongruent Neutral Congruent Duncan-Johnson & Kopell, 1981 32 PATTERN OF RTS Which is the pattern of RTs you would guess on? Color naming Word reading ) ms ( RTs 400 600 800 1000 Incongruent Neutral Congruent Duncan-Johnson & Kopell, 1981 33 SPEED OF PROCESSING THEORY . Faster processes can affect slower processes . Slower processes cannot affect faster processes RED RED 34 SPEED OF PROCESSING THEORY . Faster processes can affect slower processes . Slower processes cannot affect faster processes This effect is basically explained by our amount of reading experience, and thus by the difference in training in the two activities 35 LIMITS . Reading was made increasingly difficult by manipulating orientation uncertainty Dunbar & MacLeod, 1984 even when reading a color word was considerably slower than naming the color of ink in which the word was printed, Stroop interference persisted virtually unaltered 36 EXPLANATION Do you have any idea of why interference is occurring? Speed of Processing Theory Selective Attention Theory 37 SELECTIVE ATTENTION THEORY . The Stroop effect depends on specific circumstances and, specifically, on response set selection . Response set refers to selection on the basis of the vocabulary of eligible responses A major part of the interference caused by incongruent stimuli is specific to the members of the response set 38 SELECTIVE ATTENTION THEORY . Color words that are eligible responses produced approximately two times more interference than did color words that are not used as responses in the experiment GREEN BLUE Greater interference Lower interference Glaser & Glaser, 1989; Proctor, 1978 39 SELECTIVE ATTENTION THEORY . Color words that are eligible responses produced approximately two times more interference than did color words that are not used as responses in the experiment GREEN BLUE GREEN RTs BLUE RED Glaser & Glaser, 1989; Proctor, 1978 Incongruent Congruent 40 SELECTIVE ATTENTION THEORY . The Stroop effect depends on specific circumstances and, specifically, on response set selection . Response set refers to selection on the basis of the vocabulary of eligible responses After broad activation, selective attention is directed only to relevant processes 41 SELECTIVE ATTENTION THEORY . The Stroop effect depends on specific circumstances and, specifically, on response set selection . Response set refers to selection on the basis of the vocabulary of eligible responses Selective attention BLUE Inhibitory processes RED GREEN 42 THE STROOP EFFECT MAIN APPLICATIONS LESSON 3 LAB: COGNITIVE AND BEHAVIORAL MEASURES Luca Rinaldi 43 APPLICATIONS . In essence, Stroop’s paradigm provides a template for studying interference investigators have often mined that template to create Stroop-like tasks suited to their particular research purposes. Any guess? 44 APPLICATIONS . In essence, Stroop’s paradigm provides a template for studying interference investigators have often mined that template to create Stroop-like tasks suited to their particular research purposes. HORSE LEFT 6 6 HTH 6 6 45 APPLICATIONS . Picture-word interference task: a conflicting word is embedded in a picture Similar effect in children and adults Rosinski et al., 1975 50% congruence 46 APPLICATIONS .