Testing Reaction Times of Local and Global Perception Essay

2342 Words May 13th, 2011 10 Pages
Global and Local Processing in Visual Perception

Abstract
This study examined visual perception and the rates at which global and local features are reacted to with an aim of replicating and validating a previous experiment conducted by Navon (1977) to see if global processing was faster than local processing. There was 222 University of Newcastle students participating in the experiment, partaking in two phases, one centred round global processing, the other around local processing, where there reaction times were recorded using a computer program and imputed into a data worksheet. Results indicated that, as predicted, global processing occurred at a faster rate than local processing. It was concluded that global features were
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Set of stimuli in the test phases of global and local tasks.

Figure 2. The three display types used in identifying local features in phase two.
Both figure 1 and 2 were obtained from the original Navon report (Navon, 1977).

Procedure
Students began the experiment by adjusting the position of their head from the monitor, approximately 1 arm’s length away from the screen. They first participated in 10 practice trials for global conditions before beginning the first task. In this first task they were shown large letters made up of smaller letters. Each letter stayed on the screen for 100 milliseconds followed by a mask. When the mask appeared, students were asked to identify whether the large letter they were shown was in the shape of a H or an S. if the letter in question was a H, students pressed the z key on the keyboard, but if it was an S they saw, they were asked to press the / key. This was repeated 36 times for global test trials and response times were recorded. They then entered the task focused on local. They again participated in 10 practiced trials for local conditions. The second test trial consisted of 36 test trials in which participants were shown large letters made up of smaller letters. Each letter stayed on the screen briefly followed by a mask. When the mask appeared, it was the participant’s job to say whether the smaller letters that made up the larger letters were small H’s or S’s. Again, if they were H’s the z key was

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