3,365 research outputs found
Nonhuman primates as models of hemispheric specialization
The present chapter concerns the issue of hemispheric specialization
for perceptual and cognitive processes. In spite of a long-lasting view that only humans are lateralized (e.g., Warren, 1980), there is now strong documentation for anatomical lateralizations, functional lateralizations, or both in several animal taxa, including birds, rodents, and nonhuman primates (see Bradshaw & Rogers, 1993; Hellige, 1993). We selectively report demonstrations from studies of nonhuman primates. After a short review of the evidence for structural (anatomical) lateralization, we describe..
Associative learning in baboons and humans: Species differences in learned attention to visual features
We examined attention shifting in baboons and humans during the learning of visual categories. Within a conditional matching-to-sample task, participants of the two species sequentially learned two two-feature categories
which shared a common feature. Results showed that humans encoded both features of the initially learned category, but predominantly only the distinctive feature of the subsequently learned category. Although baboons initially
encoded both features of the first category, they ultimately retained only the distinctive features of each category. Empirical data from the two species were analyzed with the 1996 ADIT connectionist model of Kruschke. ADIT fits the baboon data when the attentional shift rate is zero, and the human data when the attentional shift rate is not zero. These empirical and modeling results suggest species differences in learned attention to visual features
Processing of above/below categorical spatial relations by baboons (Papio papio)
Three video-formatted experiments investigated the categorization of ‘above’ and ‘below’ spatial relations in baboons (Papio papio). Using an identity matching-to-sample task, six baboons correctly matched line–dot stimuli based on the ‘above’ or ‘below’ location of the dot relative to the line (Experiment 1). Positive transfer of performance was then observed when the line–dot distance depicted in the sample stimulus differed from that of the two comparison stimuli (Experiment 2). Using a go:nogo procedure, two baboons were further trained to discriminate
whether a ‘B’ character was displayed ‘above’ or ‘below’ a ‘3’ character (Experiment 3). After training, a positive transfer of performance was observed with the same type of stimuli depicted in different type fonts. Altogether, these
results suggest that baboons may form conceptual representations of ‘above’ and ‘below’ spatial relations, and categorize visual forms on that basis
Gas low pressure low flow rate metering system Patent
Flowmeters for sensing low fluid flow rate and pressure for application to respiration rate studie
High- and low-pressure pneumotachometers measure respiration rates accurately in adverse environments
Respiration-rate transducers in the form of pneumotachometers measure respiration rates of pilots operating high performance research aircraft. In each low pressure or high pressure oxygen system a sensor is placed in series with the pilots oxygen supply line to detect gas flow accompanying respiration
Comparative assessment of distance processing and hemispheric specialization in humans (Homo sapiens) and baboons (Papio papio)
This comparative study explored the ability to process distance and its lateralization in humans and baboons. Using a conditional matching-to-sample procedure in a divided-field format, subjects had to decide whether or not the distance between a line and a dot belonged to a short- or a long-distance category. Experiments 1, 2, and 4 demonstrated the ability of baboons to process and categorize distances. Moreover, humans showed better distance processing for right visual field/left hemisphere presentations than for left visual field/right hemisphere (LVF-RH) displays (Experiments 1–2). The same bias was found in baboons (Experiment 1), but in a weaker way. In Experiment 3, naive human individuals were tested and the difficulty of the discrimination was enhanced. There was a LVF-RH advantage which vanished with practice. Results are discussed by referring to theories (i.e., Kosslyn, 1987) of visuospatial processing for coordinate and categorical judgments
NMR imaging of the soliton lattice profile in the spin-Peierls compound CuGeO_3
In the spin-Peierls compound CuGeO, the commensurate-incommensurate
transition concerning the modulation of atomic position and the local
spin-polarization is fully monitored at T=0 by the application of an external
magnetic field () above a threshold value 13 Tesla. The
solitonic profile of the spin-polarization, as well as its absolute magnitude,
has been precisely imaged from NMR lineshapes obtained for
varying from 0.0015 to 2. This offers a unique possibility
to test quantitatively the various numerical and analytical methods developed
to solve a generic Hamiltonian in 1-D physics, namely strongly interacting
fermions in presence of electron-phonon coupling at arbitrary band filling.Comment: 3 pages, 4 eps figures, RevTeX, submitted to Physical Review Lette
Local and global processing. Observations from a remote culture
In Experiment 1, a normal adult population drawn from a remote culture (Himba) in northern Namibia made similarity matches to [Navon, D. (1977). Forest before trees: The precedence of global features in visual perception. Cognitive Psychology, 9, 353–383] hierarchical figures. The Himba showed a local bias stronger than that has been previously observed in any other non-clinical human population. However, in Experiment 2, their recognition of normal or distorted (“Thatcherized”) faces did not appear to have been affected by their attention to detail as has been suggested for autistic populations. The data are consistent with a cultural/experiential origin for population differences in local processing and suggest that attention to the local and global properties of stimuli may differ for hierarchical figures and faces
Cross-species differences in color categorization
International audienceBerlin and Kay (1969) found systematic restrictions in the color terms of the world's languages and were inclined to look to the primate visual system for their origin. Because the visual system does not provide adequate neurophysiological discontinuities to supply natural color category boundaries, and because recent evidence points to a linguistic origin (Davidoff, Davies, & Roberson, 1999), a new approach was used to investigate the controversial issue of the origin of color categories. Baboons and humans were given the same task of matching-to-sample colors that crossed the blue/green boundary. The data and consequent modeling were remarkably clear-cut All human subjects matched our generalization probe stimuli as if to a sharp boundary close to the midpoint between their training items. Despite good color discrimination, none of the baboons showed any inclination to match to a single boundary but rather responded with two boundaries close to the training stimuli. The data give no support to the claim that color categories are explicitly instantiated in the primate color vision system
Charge Order Driven spin-Peierls Transition in NaV2O5
We conclude from 23Na and 51V NMR measurements in NaxV2O5(x=0.996) a charge
ordering transition starting at T=37 K and preceding the lattice distortion and
the formation of a spin gap Delta=106 K at Tc=34.7 K. Above Tc, only a single
Na site is observed in agreement with the Pmmn space group of this first
1/4-filled ladder system. Below Tc=34.7 K, this line evolves into eight
distinct 23Na quadrupolar split lines, which evidences a lattice distortion
with, at least, a doubling of the unit cell in the (a,b) plane. A model for
this unique transition implying both charge density wave and spin-Peierls order
is discussed.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let
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