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A. Feinkohl, G. Klump; Temporal Flash Pattern Analysis in the Visual System of the European Starling (Sturnus Vulgaris). Invest. Ophthalmol. Vis. Sci. 2010;51(13):964.
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The faster an animal is propagating through the natural environment the better should be its visual temporal resolution. Accordingly, the critical flicker-fusion frequency (CFF) is higher in birds than in humans (e.g., Nuboer, et al. 1992, Brit. Poultry Sci. 33: 123). The CFF describes the response properties for steady-state visual signal processing. For the processing of transient visual signals, however, the double-pulse resolution (DPR) provides a better description of the processing performance. This measure reports the threshold for detecting a temporal gap between two light flashes in relation to the size of the gap. In humans, the DPR can reach about 10 ms (e.g., Treutwein & Rentschler 1992, Clin. Vision Sci. 7: 421). Here, the DPR of four European starlings (Sturnus vulgaris, a songbird) was measured in an operant Go/NoGo procedure. Four humans were tested as well for comparison.
The individuals had to detect double-flash stimuli (DFS) in a background of repeated single-flash stimuli (SFS). The duration of each flash in the DFS was 5 ms, and the gaps were varied between 1 and 60 ms for starlings and 25 and 60 ms for humans. SFS varied in duration from 11 to 70 ms. The luminance of the stimuli was also varied. Resulting psychometric functions were analyzed using signal detection theory.
For a d’ of 1.8, starling DPR thresholds ranged from 18.2 to 29.9 ms, and human DPR thresholds obtained with the same stimuli ranged from 30.7 to 37.8 ms. Starlings detected significantly shorter gaps than humans (p=0.005, t test).
Our data on DPR suggest that the starling’s visual system has a higher temporal resolution for transient stimuli than the human visual system. This finding is consistent with studies on the CFF, also indicating better temporal resolution in birds than in humans.
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