Vision Res. Vol. 22. pp. 1105 to 111 I, 1982 0042.6989/82/09 1105-07 $03.00/O Printed in Great Britain Pergaman Press Ltd zyxwvutsrqpon THE DEVELOPMENT OF THE KITTEN’S VISUAL FIELD RUXANDRA SIRETEANU* and DAPHNE MAURERt Max-Planck-Institute for Psychiatry, Kraepelinstrasse 2, 8ooO Miinchen 40, F.R.G. (Received 19 October 1981; in rerisedform 16 March 1982) Abstract-We tested the monocular visual field of 16 kittens aged 13-56 days, by observing their unreinforced visual orienting. At 13-14 days the kittens oriented toward stimuli out of 45” in the temporal visual field, but no further than 15” in the nasal field. Until 7-8 weeks, performance was significantly poorer in the nasal field than in the temporal field. This delayed development of the nasal field may be related to the relatively slow development of the uncrossed retina-genicu~ate projection and of the pathway through the visual cortex to the superior colliculus. INTRODUCTION The kitten’s vision is immature at birth. Its eyes open between 7 and 10 days, but during the next few days, the kitten seems blind. Visual orienting has not been observed until 14-21 days (Windle, 1930; Fox, 1970), and is at first elicited only by stimuli close to the midline (Norton, 1974). At 334 weeks, the kitten begins to follow moving objects, to show visual plac- ing, and to avoid the edge of a visual cliff (Fox, 1970; Norton, 1974; Van Hof-Van Duin, 1976). In the suc- ceeding weeks, all of these behaviours improve. Visual acuity also develops markedly during the first 3 months (Freeman and Marg, 1975; Mitchell et ai., 1976). In the experiments reported here, we investigated the development of the kitten’s visual field. The kitten’s general visual immaturity made us suspect that the visual field might take some time to develop completely. Several independent observations sug- gested also that different parts of the visual field might develop at different rates. In human infants, the effective visual field expands during the first few weeks of life (Tronick, 1972; Harris and MacFarlane, 1974; MacFarlane et al., 1976), and the temporal hemifieid becomes functional before the nasal hemifield (Lewis et at., 1979). In the cat, there is indirect evidence that the nasal field might also develop more slowly than the temporal field. At several levels of the cat’s visual pathway, early visual deprivation affects the receptive field properties of cells receiving input from the nasal field more severely than it affects the properties of cells receiving input from the temporal field (Hoffmann and Sireteanu, 1977; Sireteanu and Hoffmann, 1979; Singer, 1978). Moreover, abnormal visual experience *To whom all correspondence should be addressed. ton sabbatical leave from McMaster University, Hamil- ton, Ontario, Canada. early in life has a much more deleterious effect on orienting toward the nasal field than toward the tem- poral field (cf. Sherman, 1973; Van Hof-Van Duin, 1977; Tumosa et al., 1980). The relative weakness of the nasal visual field is consistent with two known patterns of visual develop- ment: (1) in several species, including the cat, the uncrossed retinofugal pathways, which subserve the nasal field, develop later than the crossed projections (Currie and Cowan, 1974; So et al., 1978; Anker, 1977); and (2) the pathway which goes through the visual cortex to the superior colliculus and which in the cat is necessary for orienting toward the nasal field, also develops relatively late (Stein et at., 1973; Norton, 1974). To test the kitten’s visual field, we were unable to use the methods which have been developed for test- ing adult cats (cf. Sprague and Meikle, 1965; Sher- man, 1973; Van Hof-Van Duin, 1977). Those methods require a period of training~uring which the kittens would have aged-and reinforcement by food, to which young kittens would not respond. Instead, we capitalized on the tendency of young kittens to orient toward salient stimuli in the peripheral visual field, without either reinforcement or training (Fox, 1970; Norton, 1974). Note that, Iike previous studies of visual perimetry, our results reflect the kitten’s ability to detect, as well as orient toward objects in different parts of the visual field. This method cannot indicate how the purely sensory visual field develops, METHODS Subjects The subjects were 16 kittens from five litters, tested at various ages between 13 and 56 days. In 11 kittens (litters III, IV and V in Table 1) we tested the entire monocular visual field; in 5 kittens (litters I and II) we tested a subset of positions chosen from 15”, 30” and 45”. Kittens younger than 6 weeks were tested three 1105