Dorsoventral asymmetry in the visual field of the bee,Apis mellifica

Summary1.Bees can be trained to a special orientation αtr of a black-and-white disk (one half black, the other half white; angular diameter 130 °), offered on a vertical screen. Different test inclinations αt of the contrast line between the black and white area of the disk are discriminated from αtr (direction sensitivity curve, Figs. 3 and 4).2.Insertions of contrasting sectors into the black and white area of the training pattern diminish the reaction frequency to that pattern (W- and B-functions, Figs. 6 and 7). Therefore the direction sensitivity curve can be approximately calculated by means of the B- and W-functions, because a rotation of the black-and-white disk is accompanied by the insertion of a white sector in the previously black area and vice versa (Fig. 5).3.The effect of inserting contrasting areas in the black-and-white disk is the stronger, the more these insertions are located in the medial lower part of the visual field (Fig. 9, Tables 3 and 4).4.The results provide strong evidence for the conclusion that the different positions of the visual field are topographically represented in the central nervous system of the bee, and that the middle lower part of the frontal visual field is most decisive for pattern recognition. They do not agree with the classical theory of form perception in insects, which is based on an integration of the stimuli effects all over the visual field, irrespective of their position within the visual field.