Scaling of the avian middle ear

This article presents a comparative study of morphology of the avian middle ear. The general morphology of the columella shows considerable variation across species, yet few studies have attempted to provide quantitative comparisons, and basic anatomical data has not been thoroughly reported. In this study, we examined the middle ear in 49 taxonomically diverse species of bird. We found significant correlations between measurements of several features (columellar length, mass, tympanic membrane area, footplate area) and interaural diameter. While scaling of columellar length with interaural diameter is consistent with isometry, masses and areas showed negative allometry, or a non-proportional scaling with interaural diameter. These observations remained true even for species with unusual middle ear morphology, such as Alcedinidae (Kingfishers) in which the basal struts of the columella form a structure almost resembling a mammalian stapes, or Tytonidae (Barn Owls) which have a highly bulbous footplate. It therefore appears that allometry cannot help explain the morphological variation in the columella.

Multimodal Integration of Spatial Information: The Influence of Object-Related Factors and Self-Reported Strategies

Spatial representations are a result of multisensory information integration. More recent findings suggest that the multisensory information processing of a scene can be facilitated when paired with a semantically congruent auditory signal. This congruency effect was taken as evidence that audio-visual integration occurs for complex scenes. As navigation in our environment consists of a seamless integration of complex sceneries, a fundamental question arises: how is human landmark-based wayfinding affected by multimodality? In order to address this question, two experiments were conducted in a virtual environment. The first experiment compared wayfinding and landmark recognition performance in unimodal visual and acoustic landmarks. The second experiment focused on the congruency of multimodal landmark combinations and additionally assessed subject’s self-reported strategies (i.e., whether they focused on direction sequences or landmarks). We demonstrate (1) the equality of acoustic and visual landmarks and (2) the congruency effect for the recognition of landmarks. Additionally, the results point out that self-reported strategies play a role and are an under-investigated topic in human landmark-based wayfinding.