1. Visual Stress and Cognition: An investigation of the impacts of visual stress on lexical decision making
Joshua Gietzen, Yu-Chi Tai, PhD,
John R. Hayes, PhD, James E. Sheedy, OD, PhD
Vision Ergonomics Research Lab
Pacific University College of Optometry
4 June 2009

2. Background
Visual Stress produces specific physical symptoms (Sheedy et al., 2003)
Certain stressors yield predictable symptoms
Cognitive tasks under visual stress are performed with equal accuracy to controls (Garzia et al., 1989)
Yet completion time is longer

3. Study Design
Measured “comprehension” in terms of response time to lexical decision task
Decide if a word is a noun or not
360 trials - 50% nouns & 50% non-nouns
Manipulated viewing conditions
Control ( 12-point font)
Small font ( 5-point)
Glare (white screen)
Blurry images (smashed images by adding a cross-hatch background, see image to right)
* Not to scale

4. How to measure cognitive processing time?
Priming Scheme
Manipulated prime types
Visual vs. Semantic vs. Neutral
Target word: CLASS
Semantic - CATEGORY
Visual - GLASS
Neutral - BOOKS
100 ms
glass
50 ms
XXXXX
Lexical Decision through voice key (times out: 1500ms)
class

5. Results – RT for correct trials

6. Results – RT for incorrect trials

7. Results – Overall Accuracy

8. Conclusions Small Font condition degrades the visual presentation.
Increases use of cognitive resources to integrate visual information, leading to an increase in comprehension time.
Small Font condition is more difficult to process, leads to a decrease in correctness of responses.
Small Font can create more cognitively stressful conditions.

9. Acknowledgement
This study was supported by Microsoft Corporation.