Does Presentation Format Influence Visual Size Discrimination in Tufted Capuchin Monkeys (Sapajus spp.)?

Most experimental paradigms to study visual cognition in humans and non-human species are based on discrimination tasks involving the choice between two or more visual stimuli. To this end, different types of stimuli and procedures for stimuli presentation are used, which highlights the necessity to compare data obtained with different methods. The present study assessed whether, and to what extent, capuchin monkeys\u27 ability to solve a size discrimination problem is influenced by the type of procedure used to present the problem. Capuchins\u27 ability to generalise knowledge across different tasks was also evaluated. We trained eight adult tufted capuchin monkeys to select the larger of two stimuli of the same shape and different sizes by using pairs of food items (Experiment 1), computer images (Experiment 1) and objects (Experiment 2). Our results indicated that monkeys achieved the learning criterion faster with food stimuli compared to both images and objects. They also required consistently fewer trials with objects than with images. Moreover, female capuchins had higher levels of acquisition accuracy with food stimuli than with images. Finally, capuchins did not immediately transfer the solution of the problem acquired in one task condition to the other conditions. Overall, these findings suggest that - even in relatively simple visual discrimination problems where a single perceptual dimension (i.e., size) has to be judged - learning speed strongly depends on the mode of presentation

Generation of internal gravity waves by a katabatic wind in an idealized alpine valley

“The original publication is available at www.springerlink.com”. Copyright Springer. DOI: 10.1007/s00703-009-0349-4The dynamics of the atmospheric boundary layer in an alpine valley at night or in winter is dominated by katabatic (or down-slope) flows. As predicted by McNider (1982) oscillations along the slope are expected to occur if the fluid is stably-stratified, as a result of buoyancy and adiabatic cooling/warming effects. Internal gravity waves must also be generated by the katabatic flows because of the stable stratification. The aim of the present paper is to identify and characterize the oscillations in the katabatic flow as well as the internal gravity wave field emitted by this flow. Numerical simulations with the ARPS code are performed for this purpose, for an idealized configuration of the Chamonix valley. We show that the oscillations near the slope are non propagating motions, whose period is well predicted by the single particle model of McNider (1982) and equal to 10 to 11 mn. As for the wave field, its frequency is close to 0.85 N, where N is the value of the Brunt-Väisälä frequency in the generation region of the waves, consistently with previous academic studies of wave emission by turbulent motions in a stratified fluid. This leads to a wave period of 7 to 8 mn.Peer reviewe

Infrasound for Detection, Localization, and Geometrical Reconstruction of Lightning Flashes

International audienc