Chapter 1. Serial vs. Parallel Processing
1.1 Introduction
Serial vs. Parallel Processing
This study replicates an experiment conducted by Treisman and Gelade (1981). Anne Treisman is known for her work on attention and perception. She formulated the feature integration theory (FIT) of attention. FIT describes perceptions of features as occurring automatically, while processing of the spatial arrangement of features or their configurations requires focused attention
1.2 Experiment Setup
1.3 Instructions
Instructions
You will need to press the space bar to begin the experiment. At the beginning of each trial, an array of letters will appear for 20 seconds. Please search the array for the stimulus that is uniquely different from the others in the array. If the target is present, press the Z key or click the ‘Target present’ button below the array. If the target is not present, click the M key or the ‘Target not present’ button.
Keyboard Responses
| Key | What Response Means |
|---|---|
| z | Target present |
| m | Target not present |
1.4 Experiment
Begin Experiment
1.5 Results
Results
1.6 Debriefing
Debriefing
Treisman and Gelade (1981) is a seminal study in visual perception and is the foundation for the majority of work in the area of visual search. Treisman and Gelade found that for a feature search (disjunction condition), reaction time was independent of the number of items in the array, whereas when conducting a conjunction search, reaction time increased along with array size. This linear increase in reaction time suggests that conjunctions are not processed preattentively, as with single features, but instead require focused, directed attention. When attention was divided, participants often formed illusory conjunctions—the erroneous re-combinations of features encountered in various stimuli. For example, when looking at green circles and red squares participants would often see red circles, an erroneous conjunction of features. Reaction time increases as the number of items to search increases because there is a response time cost to shifting attention to a large number of items in an array. This increase in processing time provides strong support for FIT.
References:
Treisman, A. M., & Gelade, G. A feature-integration theory of attention. Cognitive Psychology, 12, 97-136.
Treisman, A. M., & Schmidt, H. (1983). Illusory conjunctions in the perception of objects. Cognitive Psychology, 14(1), 107-141.
Treisman, A. M., & Sato, S. (1990). Conjunction search revisited. Journal of Experimental Psychology: Human Perception and Performance, 16, 459-478.
1.7 Quiz
Quiz