Perception of movement,the correlation model and the landing reaction of the flesh fly (Calliphoridae)

In this paper an analysis has been made of the variations in sensitivity to movement in flesh flies (Calliphoridae) when placed in front of various fixed screens structured with black and white stripes. Two vertical bands moving from the centre to the periphery were projected onto these screens. The threshold of sensitivity to these bands was measured using the landing reaction (LR). The results are compared with maximal values of theoretically predicted responses to movement, obtained using the model of non linear (2nd order) interaction between two pairs of neighbouring ommatidia (Reichardt, 1969) and taking into account the lateral inhibitory interaction between moving stripes and the background (4th order, p-order 2), as proposed by Reichardt and Poggio (1976). Experimental and theoretical results matched reasonably well except for screens with fixed alternate black and white stripes whose angular frequency ranged from 0.5 to 0.8 rad^-1, and for two screens of greatly reduced luminosity.