Hemispheric priming by meaningful and nonmeaningful symbols in language-trained chimpanzees (Pan troglodytes): Further evidence of a left hemisphere advantage.

Hemispheric priming was examined in 3 language-trained chimpanzees (Pan troglodytes) using a simple reaction time (RT) paradigm. Ss were required to hold down a response button until the occurrence of a response cue. A warning stimulus was presented to either the left visual field or the right visual field (RVF) before the response cue occurred. No warning stimulus was presented on control trials. The warning stimuli were geometric communicative symbols from 2 semantic categories: food and tools. A 3rd set of warning stimuli were familiar geometric symbols. Dependent measures included RT and the number of false-positive responses. RT data indicated an RVF advantage in priming when the warning stimuli were food or tool symbols. No significant visual half-field differences were found for familiar symbols, but a trend toward an RVF advantage was observed. These effects were enhanced when Ss responded with their left hand. False-positive data also indicated an RVF advantage for the food and tool warning stimuli. The data indicate that hemispheric asymmetries for processing communicative symbols are present in language-trained chimpanzees. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Austin H. Riesen (1913–1996): Obituary.

Presents the obituary of Austin H. Riesen, a professor and a scientist. He discovered that the primate brain was extraordinarily dependent on appropriate environments and early experiences for it to develop normally. One of his most important studies entailed rearing chimpanzees in the darrk for a signficant portion of early infancy. He has published over 70 articles and 2 books. Of special significance was the The Developmental Neuropsychology of Sensory Deprivation. His career as a researcher and professor is outlined. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cuticular hydrocarbons ofAedes hendersoni cockerell andA. triseriatus (SAY)

Field-caught adult male and femaleAedes hendersoni are difficult to distinguish from the sibling speciesA. triseriatus. We found that mosquitoes from the same sex of the sibling species can not be readily separated either by unique cuticular hydrocarbon components or by differences in percent composition of those components. Multivariate analysis of the cuticular hydrocarbon data does not provide good separation. Cuticular hydrocarbons were identified using gas chromatography electron-impact mass spectrometry and gas chromatography chemical-ionization mass spectrometry. Flame-ionization capillary gas chromatography was used for quantitative analysis of individual mosquitoes. Sixty-four hydrocarbons with chain lengths from C₁₆ to greater than C₄₆ were common to both species. Identified hydrocarbon components weren-alkanes, monomethylalkanes, dimethylalkanes, trimethylalkanes, and alkenes.Diptera: Culicidae.     

Rhesus monkeys (Macaca mulatta), video tasks, and implications for stimulus-response spatial contiguity.

Recent reports (Iwai, Yaginuma, & Mishkin, 1986; Yaginuma & Iwai, 1986) have supported the earlier conclusion by Meyer, Treichler, and Meyer (1965) and by Stollnitz (1965) that the efficiency of primate learning is compromised to the degree that there is spatial discontiguity between discriminanda and the locus of response. The research reported in this article calls for a reconsideration of this conclusion. Two rhesus monkeys (Macaca mulatta) easily mastered precise control of a joystick to respond to a variety of computer-generated targets despite the fact that the joystick was located 9 to 18 cm from the video screen. We hold that stimulus–response contiguity is a significant parameter of learning only to the degree that the monkey visually attends to the directional movements of its hand in order to displace discriminanda as in the Wisconsin General Test Apparatus. If, instead, attention is focused on the effects of the hand's movement rather than on the hand itself, stimulus–response contiguity is no longer a primary parameter of learning. The implications of this work for mirror-guided studies are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Summation in the chimpanzee (Pan troglodytes).

In this research, we asked whether 2 chimpanzee (Pan troglodytes) subjects could reliably sum across pairs of quantities to select the greater total. Subjects were allowed to choose between two trays of chocolates. Each tray contained two food wells. To select the tray containing the greater number of chocolates, it was necessary to sum the contents of the food wells on each tray. In experiments where food wells contained from zero to four chocolates, the chimpanzees chose the greater value of the summed wells on more than 90% of the trials. In the final experiment, the maximum number of chocolates assigned to a food well was increased to five. Choice of the tray containing the greater sum still remained above 90%. In all experiments, subjects reliably chose the greater sum, even though on many trials a food well on the "incorrect" tray held more chocolates than either single well on the "correct" tray. It was concluded that without any known ability to count, these chimpanzees used some process of summation to combine spatially separated quantities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Video-task assessment of learning and memory in macaques (Macaca mulatta): Effects of stimulus movement on performance.

Effects of stimulus movement on learning, transfer, matching, and short-term memory performance were assessed with 2 monkeys using a video-task paradigm (VTP) in which the animals responded to computer-generated images by manipulating a joystick. Performance on tests of learning set, transfer index, matching to sample, and delayed matching to sample in the VTP was comparable to that obtained in previous investigations using the Wisconsin General Testing Apparatus (D. M. Rumbaugh et al, 1989). Additionally, learning, transfer, and matching were reliably and significantly better when the stimuli or discriminanda moved than when the stimuli were stationary. External manipulations such as stimulus movement may increase attention to the demands of a task, which in turn should increase the efficiency of learning. Findings have implications for the investigation of learning in other populations, as well as for the application of the VTP to comparative study. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Polarization control for coherent fiber-optic systems using nematicliquid crystals

One of the obstacles to coherent fiber-optic communications is the unpredictable polarization drift which necessitates the use of an active polarization controlling system to match the polarizations of the signal and local oscillator. The polarization match must be maintained during the reset of any of the finite range components to prevent loss of data. A novel and practical system which uses three liquid-crystal devices for the polarization matching process is presented, and the required reset control algorithm and its derivation are described in detail     

Addendum to "Summation in the chimpanzee (Pan troglodytes)."

Rumbaugh, Savage-Rumbaugh, and Hegel (1987) reported that two chimpanzees (Pan troglodytes) could select, with better than 90% accuracy, the greater of two paired quantities of chocolate chips. In that study, no one quantity of chocolates (from 0 through 5) was used in both pairs on a given trial. We investigated the effect of having one quantity in common (CQ) in both pairs. Whether the other quantities (OQs) of chocolates were both less than or greater than the CQ, summation still occurred. Accuracy was primarily a function of the ratios of sums to be differentiated. This finding substantiated the earlier conclusion that summation was based on both quantities of each pair and not on some simpler process such as the avoidance of the tray with the smallest single amount or selection of the tray with the single largest amount. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Note on hand use in the manipulation of joysticks by rhesus monkeys (Macaca mulatta) and chimpanzees (Pan troglodytes).

In a recent article MacNeilage, Studdert-Kennedy, and Lindblom (1987) proposed that nonhuman primate handedness may be contingent on the specific task requirements with visual–spatial tasks yielding left-hand preferences and fine motor tasks producing right-hand preferences. This study reports hand preferences in the manipulation of joysticks by 2 rhesus monkeys (Macaca mulatta) and 3 chimpanzees (Pan troglodytes). Reach data were collected on these same subjects and served as a basis for comparison with preference data for manipulation of the joystick. The data indicated that all 5 subjects demonstrated significant right-hand preferences in manipulating the joystick. In contrast, no significant hand preferences were found for the reach data. Reaction time (RT) data also indicated that the right could perform a perceptual–motor task better than the left hand in all 5 subjects. Overall, the data indicate that reach tasks may not be sensitive enough measures to produce reliable hand preferences, whereas tasks that assess fine motor control produce significant hand preferences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)