General

Studying behavioural responses of animals in experimental conditions, ethologists have found relatively simple stimuli that could be more effective than the natural objects. Single spots (called also eye-spots) and two horizontally arranged spots, rectangular longitudinal stripes, periodic gratings and other stimuli (Fig.1) belong to them. Because the foregoing stimuli are not exact imitations of the natural objects, we will call them amimetic stimuli. In several articles, we will group the main visual amimetic stimuli and describe how they are used in the ethological research, whether they occur in the nature as well as their application in the fishing lure industry.

In the framework of applied ethology, we will address to the fishing lure industry. It is that only sphere of the human activites, where artificial stimuli and models of the various animals are used in the largest scale.

Figure 1. The basic visual amimetic stimuli

Names of the basic visual amimetic stimuli used in this article:

Note, stimuli 05 and 06 are periodic spatial, whereas stimuli 07, 08, 09, 10, 11, and 12 are periodic spatiotemporal

In the terminology of early ethologists, some of the amimetic stimuli shown above called the sign stimuli (e.g., Manning & Dawkins, 1998). Generally, using simple stimuli and changing parts of complex stimuli, scientists were able to find the so called supernormal stimuli that induced in animals the more strong behavioural responses than the modelling natural objects.

For example, the giant cane toads, Bufo marinus, respond to the horizontally moving rectangular longitudinal stripes (20 mm long x 2.5 mm high) much more actively (on average of 10 times) than to live crickets and insect plastic models (Robins & Rogers, 2004). Similarly, reproductive males of the common toad, Bufo bufo, prefer (in four cases against one) to form sexual pairs (Fig.2) with the fixed blue discs (5 cm diameter) than with the live mobile females (Gnyubkin & Kondrashev, 1978).

Figure 2. Reproductive males of toads prefer to congregate sexual pairs with blue discs than with live females

Manning and Dawkins (1998) give many other examples of this kind.

Neuroethology

Visual amimetic stimuli induce numerous behavioural responses in many animals and do not imitate, as mentioned above, the concrete natural objects. The effectiveness of these stimuli is grounded on the common mechanisms of visual perception, common for all visually guided animals. Among visual amimetic stimuli, the nature of spots, stripes and gratings, both static and moving, as well as rotating striped drums is most studied.

For example, in fish and other vertebrate animals, spots are detected at the level of ganglion cells of retina, which have the more or less distinct concentric receptive fields with the antagonistic center and periphery. According to Horn (1962; see Fig. 6.5 b,c), ... Read more »