Both male and female identity influence variation in male signalling effort

<p>Abstract</p> <p>Background</p> <p>Male sexual displays play an important role in sexual selection by affecting reproductive success. However, for such displays to be useful for female mate choice, courtship should vary more among than within individual males. In this regard, a potentially important source of within male variation is adjustment of male courtship effort in response to female traits. Accordingly, we set out to dissect sources of variation in male courtship effort in a fish, the desert goby (<it>Chlamydogobius eremius</it>). We did so by designing an experiment that allowed simultaneous estimation of within and between male variation in courtship, while also assessing the importance of the males and females as sources of courtship variation.</p> <p>Results</p> <p>Although males adjusted their courtship depending on the identity of the female (a potentially important source of within-male variation), among-male differences were considerably greater. In addition, male courtship effort towards a pair of females was highly repeatable over a short time frame.</p> <p>Conclusion</p> <p>Despite the plasticity in male courtship effort, courtship displays had the potential to reliably convey information about the male to mate-searching females. Our experiment therefore underscores the importance of addressing the different sources contributing to variation in the expression of sexually-selected traits.</p

A neural signature of rapid category-based target selection as a function of intra-item perceptual similarity, despite inter-item dissimilarity

Previous work on visual search has suggested that only a single attentional template can be prioritized at any given point in time. Grouping features into objects and objects into categories can facilitate search performance by maximizing the amount of information carried by an attentional template. From infancy to adulthood, earlier studies on perceptual similarity show that consistent features increase the likelihood of grouping features into objects (e.g., Quinn & Bhatt, 2009) and objects into categories (e.g., shape bias; Landau et al., 1988). Here we ask whether lower-level intra-item similarity facilitates higher-level categorization despite inter-item dissimilarity. Adults participated in four visual search tasks where targets were defined as either one item (a specific alien) or a category (any alien) with similar features (e.g., circle belly shape, circle back spikes) or dissimilar features (e.g., circle belly shape, triangle back spikes). Using behavioral and neural measures (i.e., N2pc ERP component which typically emerges 200 milliseconds post-stimulus), we found that intra-item feature similarity facilitated categorization, despite dissimilar features across category items. Our results demonstrate that feature similarity builds novel categories and activates a task-appropriate abstract categorical search template. In other words, grouping at the lower item level facilitates grouping at the higher category level, which allows us to overcome efficiency limitations in visual search