Brain potential correlates of supraliminal contrast functions and defocus
| Autor: | Ove Franzén, Hans Richter, Gunnar Lennerstrand |
|---|---|
| Rok vydání: | 1994 |
| Předmět: |
Physics
genetic structures business.industry media_common.quotation_subject Human Factors and Ergonomics Visual evoked potentials Retinal image Computer Science Applications Cycles per degree Human-Computer Interaction Optics Amplitude Contrast (vision) Computer vision Spatial frequency Artificial intelligence Oscilloscope business Power function media_common |
| Zdroj: | International Journal of Human-Computer Interaction. 6:155-176 |
| ISSN: | 1532-7590 1044-7318 |
| DOI: | 10.1080/10447319409526088 |
| Popis: | In six subjects with normal corrected vision, perceived suprathreshold contrast of a sine‐wave grating pattern was assessed by an intermodal matching technique in combination with the method of ratio estimation. Vertical gratings were produced on an oscilloscope screen at spatial frequencies of 1.0, 2.0, 3.5, 5.0, 9.0 and 15.0 cycles per degree (c/deg) and at contrast levels between 0.03 and 0.55. Steady‐state visual evoked potentials (VEP) were recorded from the occiput to phase‐reversing gratings of the same spatial frequency and contrast range. A linear relation was found in logarithmic coordinates between perceived and physical contrast and between VEP amplitude and physical contrast. The slopes varied with spatial frequency and were steeper at low and high spatial frequencies than in the intermediate range for both subjective contrast and VEP. In a second group of six subjects, the effect of retinal image defocus (myopia) on the psychophysical power functions was determined by placing spherical plus ... |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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