The significance of biparental care in the brown bullhead, Ictalurus nebulosus

Parental care in the brown bullhead is characterized by variation in the participation of each sex. Most broods are attended by both sexes, but some are attended by a male alone, or rarely, a female alone. Two care-givers were more successful than one alone in fostering offspring survival. However, there was no significant difference between two care-givers and one alone in the proportion of time that broods were unattended. Potential brood predators were chased less frequently by one adult alone than by adults aided by their mate. This difference may be unimportant since two adults simultaneously attended their brood only 19% of the time. Males alone attended their broods a significantly greater proportion of time than did either males or females aided by their mates. This difference suggests that males alone sustain a greater cost of care-giving (starvation and therefore reduced future reproduction) than do males aided by their mates. Thus, males alone may more often leave broods (and not return) than males that are aided in care-giving. The differential success observed may be due to a difference in the likelihood that the male (the principal care-giver) leaves the brood permanently, rather than differences in the quality of care one or two adults provide. I suggest that two care-givers are more successful than one because the net benefits of care-giving exceed the net benefits of leaving for males when aided by their mates.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42631/1/10641_2004_Article_BF00005153.pd

Effects of asynchrony on symmetry perception,Psychologische Forschung

Item does not contain fulltextThe effect of temporal image segmentation on symmetry perception was investigated by means of stimuli composed of one part surrounding another. The two parts could be presented synchronously or with a temporal offset (20-100 ms), and each part could be either symmetrical or random. The task was to discriminate completely symmetrical (S) stimuli (in Experiment 1) or completely random (R) stimuli (in Experiment 2) from partially symmetrical (PS) stimuli in which one part was symmetrical and the other random. The R stimuli showed an asynchrony effect but the S stimuli did not. Furthermore, in both experiments, the PS stimuli showed an asynchrony effect when the symmetrical part was presented last but not when the symmetrical part was presented first (independent of whether it was the surrounded part or the surrounding part). Both results suggest that symmetry is strong enough to override this kind of temporal image segmentation.8 p

Cognitive ornithology: the evolution of avian intelligence

Comparative psychologists interested in the evolution of intelligence have focused their attention on social primates, whereas birds tend to be used as models of associative learning. However, corvids and parrots, which have forebrains relatively the same size as apes, live in complex social groups and have a long developmental period before becoming independent, have demonstrated ape-like intelligence. Although, ornithologists have documented thousands of hours observing birds in their natural habitat, they have focused their attention on avian behaviour and ecology, rather than intelligence. This review discusses recent studies of avian cognition contrasting two different approaches; the anthropocentric approach and the adaptive specialization approach. It is argued that the most productive method is to combine the two approaches. This is discussed with respects to recent investigations of two supposedly unique aspects of human cognition; episodic memory and theory of mind. In reviewing the evidence for avian intelligence, corvids and parrots appear to be cognitively superior to other birds and in many cases even apes. This suggests that complex cognition has evolved in species with very different brains through a process of convergent evolution rather than shared ancestry, although the notion that birds and mammals may share common neural connectivity patterns is discussed

Combining Biometric Evidence for Person Authentication

Humans are excellent experts in person recognition and yet they do not perform excessively well in recognizing others only based on one modality such as single facial image. Experimental evidence of this fact is reported concluding that even human authentication relies on multimodal signal analysis. The elements of automatic multimodal authentication along with system models are then presented. These include the machine experts as well as machine supervisors. In particular, fingerprint and speech based systems will serve as illustration. A signal adaptive supervisor based on the input biometric signal quality is evaluated