Christine P. MaloneMinnesota State University Moorhead

What does the Stroop effect tell us about perception?

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 such as GREEN appears in an ink

color such as red. The task is to name the color of the ink for each item.

Try it.

Note that some times the task is to read the word and ignore the color…Also note that sometimes 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.

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 called into question.

RationaleThis 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

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

ResultsConducted 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 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.

Color naming is more automatic than shape naming.

Experiment 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 extent

Experiment 3After 20 days of shape naming practice, the

original asymmetry was reversed. At this point, the presence of colors no longer had any influence on the naming of shapes. However, an incongruent shape no interfered strongly with color naming.

With all the practice, shape naming is now more automatic than color naming

What are the variables?Dependent variablesIndependent variablesControl variablesConverging operations

More connections to the chapter:Is an automatic process an all-or-nothing

event?Experience influences automaticity.We can alter (through training) the

perceptual characteristics we pay attention to.

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?