Expert musicians and non-musicians of similar educational and social class background were compared in two experiments involving perception of timbre and rhythm. In Experiment 1 where dichotic monitoring for the sound of the violin was required, there was a practice effect but no ear or group differences. The rhythm monitoring experiment produced a group by ear interaction with musicians faster on the right ear than the left and faster than non-musicians on the right ear only. Analysis of strategies reported by subjects showed that verbal labelling did not apparently influence laterality. Lack of evidence for individual laterality effects reinforces the claim that with stringent experimental and subject controls there is minimal evidence for musicians non-musician laterality effects.

Calculation and number processing require ideographic and semantic operations which may involve the right as well as the left hemisphere. There is often also present a spatial component, whether overt as with column-addition or multiplication procedures, or covert if numbers are recoded into continuously varying analog quantities or magnitudes of a psychophysical or imaginal nature, to facilitate numerical comparison. Again right hemisphere mechanisms may be partly responsible. Evidence for such a minor hemisphere contribution is reviewed in the light of studies with clinical and commissurotomy cases, and normal subjects. Calculation itself is hard to define, as it often seems to reduce to the operation of overlearn, associative, tabular look-up functions and algorithms. Indeed alphabetic comparisons analogous to numerical tasks should generate similar laterality effects in clinical and normal populations.

The Australian pelican Pelecanus conspicillatus is the largest of all pelican species and can consume up to half their body weight per day, feeding predominantly on teleost fishes. Anecdotally, it has been suggested that pelicans preferentially avoid the consumption of small portions of elasmobranch fishes (e.g. sharks and rays), which prompted this investigation into their food discrimination behaviour. The large differences in the osmolarity and/or urea content between elasmobranch and teleost fishes are likely to underpin this behaviour. Osmoconformers such as elasmobranchs maintain an internal osmotic concentration similar to seawater, with this state being achieved primarily by the retention of the osmolyte urea, while other osmoconforming organisms such as squid likely conserve ions such as Na+ and Cl–. In contrast, osmoregulating teleosts maintain an osmolarity much lower than seawater and approximately the same as pelicans. Consequently, ingestion of teleost fishes results in minimal water movement; however, if a large bolus of osmoconformers are consumed this may lead to dehydration. It was hypothesized that pelicans would preferentially avoid the consumption of osmoconformers and accept osmoregulators. In addition, we investigated the underlying physiological basis for elasmobranch rejection, and which sense(s) are primarily utilized for such behaviour. We found that pelicans freely chose to accept offerings of osmoregulators at a significantly greater frequency than osmoconformers. Furthermore, the osmotic concentration (and not specifically urea) was considered to be the most likely cause of rejection, as squid, which do not conserve urea, were rejected equally as often as elasmobranchs. Finally, vision appears to be the sense utilized for this behaviour because when elasmobranchs were made to appear visibly ‘similar’ to teleost fishes they were consumed at equal frequencies. This study provides new insight into food discrimination in pelicans and might also be applicable to other seabirds.