What does the Stroop effect tell us about perception? Christine P. Malone Minnesota State University Moorhead

An Enduring Debate 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. Bottom-Up Processing (direct approach to perception): Analyzing information starting at the bottom (small units) and going upward to form a complete perception Top-Down Processing (indirect approach to perception): Preexisting knowledge that is used to rapidly organize features into a meaningful whole

Evidence for Top-Down Shape & Size Constancy

Evidence for Bottom-Up Feature detector approach These 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 opposites Motion aftereffects support the existence of feature detectors Try this

Imposing Meaning Figure 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. RED GREEN Note that some times the task is to read the word and ignore the color…Also 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? Automaticity

Two popular explanations offered: Relative speed of processing—word 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 automatic—rapid, independent of processing strategy, and not reliant upon cognitive resources…an “all or nothing” construct. But both of these accounts have been questioned.

Rationale This study aimed to produce evidence for a continuum of automaticity view—practice 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 shapes

My version of the stimuli—Color naming baseline blue orange pink green Experiment 1—Initial training varied—16 trials, 192 trials, 288 trials, 576 trials P was to name the shape out loud as quickly as possible without making a mistake--

My version of the stimuli-- For control shape naming & shape training blue orange pink green

Test Phase—Name the shape (ignore ink color) congruent & incongruent blue orange pink green blue orange pink green

Test Phase—Name the ink color (ignore shape) congruent & incongruent blue orange pink green orange green blue pink

Results Conducted 3 experiments manipulating extent of practice with the shape-naming task Is it possible to manipulate interference with training? If so, this would be evidence against a strong view of automaticity—that processes are either automatic or controlled.

Experiment 1 On 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.

Color naming is more automatic than shape naming. Experiment 1 Color naming is more automatic than shape naming. Naming time (msec) Those with max training had two hours of training…

Experiment 2 After 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 extent

Experiment 2 Just as much time to name color and ignore shape(previously automatic) as name shape and ignore color (began as completely controlled process)

Experiment 3 After 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 3 With 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?