Red–green flicker resolution as a function of heterochromatic luminous modulation

Abstract

Critical fusion frequencies have been evaluated in heterochromatic red-green flicker as a function of red-green luminous modulation defined by mL = (R-G)/(R+G)%, at five different mean luminance levels, two test sizes (2 degrees and 5 degrees) and square wave stimuli. The extreme values mL = +/- 100 correspond to ordinary light-dark flicker (red or green); mL = 0 corresponds to pure chromatic flicker, and any other values correspond to simultaneous luminous and chromatic flicker. To implement the stimuli we have developed a new stimuli generator (AVICO, colour vision analyser) using bicolour LEDs as the light source and electronic control of the luminances and frequencies. The results for any luminance level and both test sizes show a minimum critical fusion frequency in the case of pure chromatic flicker (photometric match condition) and a critical fusion frequency which is slightly higher in the green extreme (mL = -100) than in the red (mL = +100). The shape of the variation between the minimum and the extremes is consistent with the results recently reported by Swanson and the theoretical models for the luminance channel response to heterochromatic flicker.

The edge of awareness: Mask spatial density, but not color, determines optimal temporal frequency for continuous flash suppression

“…An additional limiting factor to the improvement in mask effectiveness with higher temporal frequencies may be flicker fusion. While critical (absolute) flicker fusion (the point where a flickering patch gives the same perceptual impression as a patch of constant brightness) is generally reported at higher frequencies than tested in the current study (Brindley, Du Croz, & Rushton, 1966;Capilla & Aguilar, 1993), perceived contrast can already be significantly reduced at much lower frequencies. Increasing the temporal frequency of the mask display may therefore reduce the effective contrast of the masks, in turn reducing masking effectiveness.…”

Individual Resting-state alpha peak frequency and within-trial changes in alpha peak frequency both predict visual flash segregation performance

“…This is not to say that every aspect of visual (or multisensory) 391 processing operates at this same frame rate (see, for example: ). 392 Some forms of flicker, for example, are visible at faster rates (Landis, 1953;Brindley 393 et al, 1966;Campos and Bedell, 1978;Capilla and Aguilar, 1993). One possible 394 interpretation of the current set of findings is that rapid individuation of objects as 395 distinct entities in space and time involves this 10Hz rhythm, while processing of more 396 complex objects and events may involve slower rhythms, in the theta range (…”