Separate detectors for simple and complex grating patterns?

Andrew M. Derrington, David R. Badcock

Research output: Contribution to journalArticlepeer-review

132 Citations (Scopus)


Gratings having two sinusoidal components show a periodic variation in contrast which is visible as a "beat" pattern. The spatial frequency of the beat is the difference between the frequencies of the two components. Thresholds for a number of detection and discrimination tasks were measured using beat patterns of 1 c/deg (with components of 9 and 10 c/deg), and gratings of 1 and 10 c/deg. Temporal modulation at 6 Hz lowered detection thresholds for 1 c/deg gratings, but not for beats or 10 c/deg gratings. The effect of contrast on the range of temporal frequencies over which direction of movement can be discriminated differs for the three types of pattern: beats resemble neither low nor high spatial frequency gratings. Low and (for 2 of 3 observers) high spatial frequency gratings, but not beat patterns, are susceptible to a movement after effect induced by a low spatial-frequency grating. Beat patterns induce little or no movement after effect. We conclude that beat patterns are not detected by the same mechanisms that detect simple gratings.

Original languageEnglish
Pages (from-to)1869-1878
Number of pages10
JournalVision Research
Issue number12
Publication statusPublished - 1985
Externally publishedYes


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