Slide 1

Christine P. MaloneMinnesota State University MoorheadWhat does the Stroop effect tell us about perception?An Enduring DebateDirect vs. indirect, bottom-up vs. top-down, data-driven vs. conceptually driven processing are all commenting on the same basic theoretical debate in perception.

Bottom-Up Processing: Analyzing information starting at the bottom (small units) and going upward to form a complete perceptionTop-Down Processing: Preexisting knowledge that is used to rapidly organize features into a meaningful whole

Evidence for Bottom-UpFeature detector approachThese feature detector cells work by summing up sensory input of orientation, motion, etc.Feature detectors are wired in the visual system in terms of paired oppositesMotion aftereffects support the existence of feature detectorsTry this

Evidence for Top-DownShape & Size Constancy

Imposing Meaning5Figure 4.53(a) Shape constancy: We perceive all three doors as rectangles. (b) Size constancy: We perceive all three hands as equal in size.

Please shout out the answers to the questions.

Perceptual Expectancies (Set)Perceptual Set: Readiness to perceive in a particular manner, induced by small expectations

Macleod, C.M. & Dunbar, K. (1988). Training and Stroop-Like Interference: Evidence for a Continuum of Automaticity. Journal of Experimental Psychology: Learning, Memory, and Cognition, 14, 126-135.What is the Stroop effect?A color word appears in an ink color such as red. The task is to name the color of the ink for each item. REDGREENNote that some times the task is to read the word and ignore the colorAlso note that some times the ink color and written word are congruent and sometimes incongruent.

The impact on performance is asymmetrical. The word interferes with naming the color, but the color does not interfere with reading the word. Why? AutomaticityTwo popular explanations offered:Relative speed of processingword reading and color naming are carried out in parallel. Word reading is the faster process so it can interfere with the slower process.Automaticity account--certain processes (like reading isolated words) are automaticrapid, independent of processing strategy, and not reliant upon cognitive resourcesan all or nothing construct.But both of these accounts have been questioned.RationaleThis study aimed to produce evidence for a continuum of automaticity viewpractice is important in producing automaticity, suggesting that automaticity exists on a continuum and may be learned.So practicing one component should lead to increased automatization of that component, resulting in increased interference to that component when it must be ignored.Experimenters created a new task so that effects of practice could be controlled and observed from the outset.Selected a set of unfamiliar shapes and then assigned color names to the shapesMy version of the stimuliColor naming baseline blue

orange

pink

greenExperiment 1Initial training varied16 trials, 192 trials, 288 trials, 576 trials

P was to name the shape out loud as quickly as possible without making a mistake--13My version of the stimuli--For control shape naming & shape training blue

orange

pink

greenTest PhaseName the shape (ignore ink color)congruent & incongruent blue

orange

pink

green blue

orange

pink

greenTest PhaseName the ink color (ignore shape)congruent & incongruent blue

orange

pink

green orange

green

blue

pinkResultsConducted 3 experiments manipulating extent of practice with the shape-naming taskIs it possible to manipulate interference with training?If so, this would be evidence against a strong view of automaticitythat processes are either automatic or controlled.

Experiment 1On day 1, Strong asymmetry with minimal training. When asked to name shapes, incongruent colors interfered and congruent colors facilitated. However, shapes had no effect on color naming.

Experiment 1Color naming is more automatic than shape naming.Naming time (msec)Those with max training had two hours of training19Experiment 2After five days of training, interference became symmetrical, occurring in both directions to the same extent that it occurred earlier in only one direction. This pattern carried over to a test 3 months later without any additional practice on shape naming.

Both color naming and shape naming are automatic to the same extentExperiment 2Just as much time to name color and ignore shape(previously automatic) as name shape and ignore color (began as completely controlled process)

Experiment 3After 20 days of shape naming practice, the original asymmetry was reversed. At this point, the presence of incongruent colors no longer had any influence on the naming of shapes. However, an incongruent shape still interfered strongly with color naming.Experiment 3With all the practice, shape naming is now more automatic than color naming.

More connections to the area:Is an automatic process an all-or-nothing event?Experience influences automaticity.We can alter (through training) the perceptual characteristics we pay attention to.

What do you think?Direct vs. indirect, bottom-up vs. top-down, data-driven vs. conceptually driven processing are all commenting on the same basic theoretical debate in perception. What does the Stroop effect add?