Daytime conspicuity of fluorescent and non-fluorescent color targets was investigated in the field against a green background in terms of visual detection and recognition, as a function of the peripheral angle and the target size. Two groups of 9 young, healthy subjects each were used. The colors white, blue, green, red, fluorescent red, fluorescent yellow-green, yellow, fluorescent yellow, orange, fluorescent orange were presented for 2 seconds at a radial distance of 30m under the peripheral viewing angles of 10°, 20°, 30° for group 1, and 30°, 40°, 50° for group 2. The target sizes 0.076m x 0.152m, 0.114m x 0.229m, and 0.152m x 0.305m were used in group 1, and 0.114m x 0.229m, 0.152m x 0.305m, and 0.229m x 0.457m were used in group 2. Fluorescent color targets (especially fluorescent yellow-green) were better peripherally detected than the non-fluorescent color targets. White, blue, and green were better recognized but exhibited relatively poor peripheral conspicuity. Therefore it appears that if one wants to maximize the peripheral daytime conspicuity, both highly conspicuous fluorescent colors along with a fairly large target size should be selected. Such a target configuration may for example be needed to attract a driver's attention in situations where a target is located in an observer's visual periphery (peripheral angle > 20°), for example a target approaching a driver at an intersection from a left or right side street.
An integrated network for invariant visual detection and recognition