Faculty Bibliography

We argue that in many circumstances, human observers evaluate sensory evidence simultaneously under multiple hypotheses regarding the physical process that has generated the sensory information. In such situations, inference can be optimal if an observer combines the evaluation results under each hypothesis according to the probability that the associated hypothesis is correct. However, a number of experimental results reveal suboptimal behavior and may be explained by assuming that once an observer has committed to a particular hypothesis, subsequent evaluation is based on that hypothesis alone. That is, observers sacrifice optimality in order to ensure self-consistency. We formulate this behavior using a conditional Bayesian observer model, and demonstrate that it can account for psychophysical data from a recently reported perceptual experiment in which strong biases in perceptual estimates arise as a consequence of a preceding decision. Not only does the model provide quantitative predictions of subjective responses in variants of the original experiment, but it also appears to be consistent with human responses to cognitive dissonance.

The evolution of genetic networks is a fascinating and complex topic that has long intrigued researchers. The genetic network controlling early embryonic patterning in Drosophila represents one of the best understood networks in developmental biology. Thus, the realization that major components of the network are not conserved features of insect embryogenesis provided the scientific field with an incredible opportunity to begin comparative studies between the well-studied Drosophila network and the genetic networks of other insect species. Moreover, the tremendous diversity among insects provides a wide variety of species to sample the conserved and novel developmental features that have evolved over time. The application of genetic screens, transgenic analysis and in particular, the development of pRNAi in various insect model systems has also contributed significantly to the advancement of the field of evolution and development. The results presented in recent reports regarding Nasonia, Tribolium, Oncopeltus and Gryllus embryonic patterning have shown the power of comparative studies between different insects for studying evolution and development. This review will focus on the establishment of the wasp Nasoniavitripennis as a powerful model system for elucidating the various biological strategies employed during insect embryogenesis. Moreover, work presented throughout this review will highlight important results regarding comparative studies between the fruit fly and the wasp

Object recognition is a crucial component of both visual and auditory perception. It is also critical for olfaction. Most odours are composed of 10s or 100s of volatile components, yet they are perceived as unitary perceptual events against a continually shifting olfactory background (i.e. figure-ground segregation). We argue here that this occurs by rapid central adaptation to background odours combined with a pattern-matching system to recognise discrete sets of spatial and temporal olfactory features-an odour object. We present supporting neuropsychological, learning, and developmental evidence and then describe the neural circuitry which underpins this. The vagaries of an object-recognition approach are then discussed, with emphasis on the putative importance of memory, multimodal representations, and top-down processing