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Experiment Author: Adapted from STEP and used with permission of Brian MacWhinney
This experiment compares times to find a "Z" in a column of round letters (O, S, Q) vs. a column of angular letters (K, E, L). It predicts that finding an angular letter in a field of round letters would be easier because the distractors have fewer features in common with the target.
The article on which this experiment is based is fairly long and deals with the general concept of visual search (finding a face in a crowd, or a name in a telephone book). The particular part replicated here deals with context effects and effects of position in visual search. It involves a display that is 24 lines long, with 6 letters in each line. The target is the letter "Z". The two factors of interest are whether the letters other than the target resemble it, and where the target is in the display (line 3, 6, 9, 12, 15, 18, 21, or 24). The experiment hopes to show that reaction time varies directly with the position of the item in the display and that finding the target is twice as fast if it does not resemble the distractor letters.
In this experiment, locate the letter "Z" and press the space bar as quickly as possible after seeing the letter "Z". The target letter "Z" will be surrounded by other letters that will alternate between angular letters like "K" or "X", or rounded letters like "O" or "B". This experiment contains 128 trials.
Neisser, U. (1964). Visual search. Scientific American 210(6), 94-102.