Approach behaviour and embryonic visual experience in chicks: Studies of the effect of rate of visual flicker

Abstract

It has been demonstrated that visual stimulation during the latter part of embryonic development will have its effect on subsequent approach behaviour in the chick. Stimulation here had been of a non-specific type, i.e. mere presence or absence of illumination. This study was conducted to see how much specific stimulation like visual flicker applied during the latter part of embryonic development would affect approach to the same or similar stimuli. In experiment 1 extremely slow flicker (6·6 and 20 c/min) was applied to the eggs under incubation. Treatment groups were tested for approach on flickering and non-flickering stimuli after hatching. Results show that exposing the eggs to flicker has an effect on approach behaviour. Groups that received flicker at a rate of 20 c/min approach faster than those which received flicker at the rate of 6·6 c/min. A significant improvement over trials was only found in the group which received flicker of 20 c/min during the embryonic period. In experiment 2 which employed a range of very much faster flicker no significant treatment effects became apparent. These results suggest that visual flicker as embryonic stimulation is effective in priming the embryo to yield better approach performance after hatching. Results of experiment 2 indicate that the effect of flicker as embryonic stimulation may operate over a certain range in affecting subsequent approach performance.