Marken R, Pettersen J
Percept Mot Skills. 1979 Aug;49(1):315-8. doi: 10.2466/pms.1979.49.1.315.
An experiment was done to determine how the sequence and variety of irrelevant items affects the speed of visual search. Three subjects searched for a target letter in sequences of predominantly alternating or repeating letters. Search through repeating sequences was faster than search through alternating sequences. Increasing the variety of irrelevant letters slowed search through alternating but not repeating sequences. Implications regarding eye fixations during visual search are discussed.