Laterality in hand preferences and reaching accuracy of cotton-top tamarins (Saguinus oedipus).

Manual laterality of cotton-top tamarins (Saguinus oedipus) was observed for five different types of reaching. The tamarins displayed species-level right-handedness for spontaneous grasping for food but not for one-arm vertical suspension or any of 3 other types of elicited reaching. The results showed that difficult or novel tasks are neither necessary nor sufficient for the emergence of species-level handedness. Accuracy in retrieving food from a rotating platform was greatest (a) for highly lateralized tamarins, (b) when the preferred hands were used for reaching, (c) for young tamarins, and (d) when the tamarins stood on a narrow, unstable platform instead of a wide, stable one. The results suggest that evolution of species-level handedness is dependent on prior natural selection for increased manual performance that accompanies strongly lateralized hand preferences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multiple measures of hand-use lateralization in the ring-tailed lemur (Lemur catta).

Evaluated a free-ranging matriline of 13 ring-tailed lemurs (Lemur catta) from videotaped records for lateralized hand use with 2 tasks and 4 measures: food reaching, feeding posture, duration of food holding, and manipulation of food between mouth and hand while eating. Binomial z scores determined 7 lemurs to be left preferent in reaching, 3 right, and 3 ambipreferent. Ideographic analyses suggested possible sex-linked and early experience twin effects. When compared to right and ambipreferent lemurs, left reach preferent lemurs used the left hand more but bimanuals grasped less in food holding and also engaged in less hand-mouth food manipulation. The tendency to manipulate food was not correlated with bimanual holding but was inversely related to left hand holding and directly related to right hand holding. These patterns are discussed as possible precursors of human bimanual manipulation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of lateralized components of feeding behavior in the ring-tailed lemur (Lemur catta).

Twenty-one ring-tailed lemurs (Lemur catta) were videotaped during feeding. They had previously been classified as left-, right- or ambipreferent on the basis of the hand used to reach for food. The feeding sequences provided duration-based measures of manipulation, hand and mouth lateralization, and posture during feeding sequences with 2 types of food. Hand preference for reaching and holding was stable over time and across measurement conditions. As a group, the lemurs grasped fruit bimanually more often than chow; however, right- and ambipreferent lemurs spent more time holding food bimanually than did left-preferent ones. Older animals consumed chow more quickly than did younger animals but did not differ in their rate of manipulation. Lemurs had a preference for using one side of the mouth in feeding, but this had no directional relation to preferred hand. Three postural feeding patterns were identified. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Color preferences in gorillas (Gorilla gorilla gorilla) and chimpanzees (Pan troglodytes).

Color plays an important biological role in the lives of many animals, with some species exhibiting preferences for certain colors over others. This study explored the color preferences of two species of ape, which, like humans, possess trichromatic color vision. Six western lowland gorillas, and six chimpanzees, housed in Belfast Zoological Gardens, were exposed to three stimuli (cloths, boxes, sheets of acetate) in red, blue, and green. Six stimuli of the same nature, in each of the three colors, were provided to both species for 5 days per stimulus. The amount of interest that the animals showed toward each stimulus of each color was recorded for 1 hr. Results showed that the apes, both when analyzed as two separate groups, and when assessed collectively, showed significant color preferences, paying significantly less attention to the red-, than to the blue- or green-colored stimuli. The animals' interest in the blue- and green-colored stimuli did not differ significantly. Overall, the findings suggest that gorillas and chimpanzees, our closest living relatives, may harbor color preferences comparable to those of humans and other species. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Can lemurs learn to deceive? A study in the black lemur (eulemur macaco).

Deceptive behavior in primates has been the focus of a number of studies. Nevertheless, such abilities have never been demonstrated in prosimians. The authors' goal was to analyze possible deception in lemurs according to a paradigm used with simians. Three black lemurs were trained to communicate about the location of a hidden reward with a cooperative trainer. Afterward, when a 2nd trainer and lemurs competed to gain access to the reward, each subject differentially adapted its learned behavior to the context. Their performances with the cooperative trainer remained stable while they showed various behavioral adjustments when faced to the competitive trainer: 1 subject refused to participate, another preferentially withheld information, and the 3rd sometimes pointed deceptively to obtain the reward. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social transmission of food preferences in adult hooded rats (Rattus norvegicus).

When given a choice between 2 novel diets, rats show a marked preference for the diet that a paired conspecific has been eating. Four experiments were conducted to investigate this transmission of a food preference from one rat to another. Ss were 340 male Long-Evans hooded rats that were paired into observers and demonstrators. Demonstrators were presented with 2 novel foods, one adulterated with quinine sulfate, after which the observers were presented with the same novel diets, neither of which was adulterated with quinine. These studies suggest that (a) the effect is socially mediated, (b) the learning is very rapid, and (c) the preference can last for at least 5 days. Results are discussed in the context of other instances of social transmission of food-related behaviors and in terms of social learning in general. Findings stress the importance of divising animal learning paradigms in accord with the natural history of the animal being studied. (43 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of hand preferences in marmosets (Callithrix jacchus) and effects of aging.

The authors investigated the development of unimanual hand use and hand preferences during feeding in 15 marmosets (Callithrix jacchus), ages birth to 51–70 months. Bimanual hand use was common at 1–2 months, but by 5–8 months unimanual holding had developed and so had significant hand preferences. Half of the marmosets preferred to pick up and take food to the mouth with the left hand, and half preferred the right hand. Individuals maintained the same hand preference at all ages examined. Significant relationships were also found between the postures adopted during feeding and the direction of hand preferences displayed by juvenile marmosets. There was a positive correlation between increased suspension and increased left-hand preference, and a negative correlation between increased feeding in a tripedal posture and increased left-hand preference. These results are discussed in terms, of motor development and hemispheric specialization. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social transmission and memory of food preferences in pine voles ( Microtus pinetorum ).

The social transmission of food preferences is affected by factors including the length of time preference is maintained. The authors investigated the-social transmission of food preferences in pine voles (Microrus pinelorum) and whether food items had to be present for memory to persist. A demonstrator vole was fed cocoa-flavored food, a nonpreferred food. After interacting with a demonstrator vole, observer voles prefer-red cocoa-flavored food as compared with either naive voles that had not interacted with demonstrators or voles that had been exposed to odors. Observers retained the preference for 72 hr after interacting with an observer whether or not flavored foods were present. The ability to learn which food items are palatable and safe may benefit a generalist herbivore that has face selection to avoid toxic baits. (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)     

Hand preferences in unimanual and coordinated-bimanual tasks by tufted capuchin monkeys (Cebus apella).

Hand preferences in 26 capuchin monkeys (Cebus apella) were examined in 2 reaching-for-food tasks under 2 postural conditions. In the 1st task (unimanual), monkeys were required to reach for food from both a quadrupedal and an upright posture. A right-hand bias was found for the upright but not for the quadrupedal condition. In the 2nd task (coordinated bimanual), monkeys were required to extract the food from a hanging Plexiglas tube from both a crouched and an upright posture. A right-hand bias was found for both conditions. A significant increase in right-hand use was noted from the unimanual, quadrupedal, reaching task to the coordinated-bimanual task, with females exhibiting a greater right-hand preference than males. In addition, a significant effect of task complexity on strength in laterality was found. Results are discussed in the context of recent theories on primate laterality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Developmental exposure to oxytocin facilitates partner preferences in male prairie voles (Microtus ochrogaster).

The authors investigated the effects of postnatal manipulations of oxytocin (OT) on the subsequent tendency to form a partner preference in male prairie voles (Microtus ochrogaster). Neonatally, males received either an injection of OT, an oxytocin antagonist (OTA), 0.9% saline vehicle, or handling without injection. As adults, males were tested for partner preference following 1 hr of cohabitation with a nonestrous female. In a 3-hr preference test, males neonatally exposed to exogenous OT exhibited a significant partner preference, not seen in males receiving OTA or saline. Both OT and OTA voles had significantly higher levels of social contact than saline controls. A single neonatal injection of OT increased both total and selective social behaviors in male prairie voles. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Exposure to various stressors alters preferences for natural odors in rats (Rattus norvegicus).

Male Sprague-Dawley rats were given choice tests (Test 1) in a maze with the odors of clean bedding, citronella, an alpha colony (ACO), shocked conspecifics (SCO), or a predator cat (PCO). In Exps 1–3, groups were exposed to no stress, defeat by a conspecific, or shocks. During subsequent tests (Test 2), nonstressed rats showed no change in odor preferences; defeated rats showed a nonsignificant reduction in preference for ACO; and shocked rats showed significant preference reductions for SCO and PCO and a significant increase in preference for ACO. In Exp 4, odors of isolated, nonstressed conspecifics (CO) were preferred more than ACO, for rats given shock before Test 2. In Exp 5, rats significantly preferred CO over ACO when exposed to a caged cat during Test 2. Because of exposure to stress, rats later avoided certain fear odors and showed strong preferences for the odors of nonstressed CO. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hand preferences in unimanual and bimanual feeding by wild vervet monkeys (Cercopithecus aethiops).

Lateral preference was examined in spontaneous feeding actions in 2 troops of wild vervet monkeys (Cercopithecus aethiops). Processing of 4 foods (termites, leaf shoots, sugarcane, and fruit) was studied. Actions included unimanual reaching to moving objects, operating from an unstable posture, and coordinated bimanual processing. Between 19 and 31 subjects were available, according to the task. In 2 tasks, laterality of 2 independent stages was measured separately, giving 6 measures in all. On 4 of these measures, most monkeys were ambipreferent, and only a few showed significant hand preferences. Only for termite feeding and detaching material from fruits did the majority show significant lateralization; no tasks elicited exclusive use of 1 hand. Preference appeared labile, because in 2 tasks, population trends reversed with increasing age. No population trends to left or right were found; instead, these monkeys showed ambilaterality, with lateralization associated with task complexity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spectral preferences and the role of spatial coherence in simultaneous integration in gray treefrogs (Hyla chrysoscelis).

The perceptual analysis of acoustic scenes may often require the integration of simultaneous sounds arising from a single source. Few studies have investigated the cues that promote simultaneous integration in the context of acoustic communication in nonhuman animals. This study of Cope's gray treefrog (Hyla chrysoscelis) examined female preferences based on spectral features of conspecific male advertisement calls to test the hypothesis that cues related to common spatial origin promote the perceptual integration of simultaneous signal elements (harmonics). The typical advertisement call comprises two harmonically related spectral peaks near 1.1 kHz and 2.2 kHz. Females generally exhibited preferences for calls with two spatially coherent harmonics over alternatives with just one harmonic. When given a choice between a spatially coherent call (both harmonics originating from the same speaker) and a spatially incoherent call (each harmonic from different spatially separated speakers), females preferentially chose the former in the same relative proportions in which it was chosen over single-harmonic alternatives. Preferences for spatially coherent calls over spatially incoherent alternatives did not appear to result from greater difficulty localizing the spatially incoherent sources. These results are consistent with the hypothesis that spatial coherence promotes perceptual integration of simultaneous signal elements in frogs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Male preferences for unmated versus mated females in two species of voles (Micotus ochrogaster and M. montanus).

Examined male preference for unmated vs mated females in 2 species of voles, using 73 prairie voles and 78 montane voles in 2 testing situations each. In Exp I, conducted in a tether test situation, prairie voles spent significantly more time and copulated more with unmated than with mated females. In Exp II, male prairie voles spent significantly more time visiting and investigating anesthetized unmated females than anesthetized mated females. In Exp III, male montane voles showed no significant visitation or copulatory preference for unmated vs mated females in the tether situation. In Exp IV, male montane voles spent more time with unmated, anesthetized females than mated females but displayed no other significant differences. In general, male prairie voles appeared more discriminating in their mate choice than male montane voles. These differences are consistent with differences in male parental effort in the field. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Female condition influences preferences for sexual dimorphism in faces of male humans (Homo sapiens).

In some species, female condition correlates positively with preferences for male secondary sexual traits. Women's preferences for sexually dimorphic characteristics in male faces (facial masculinity) have recently been reported to covary with self-reported attractiveness. As women's attractiveness has been proposed to signal reproductive condition, the findings in human (Homo sapiens) and other species may reflect similar processes. The current study investigated whether the covariation between condition and preferences for masculinity would generalize to 2 further measures of female attractiveness: other-rated facial attractiveness and waist-to-hip ratio (WHR). Women with high (unattractive) WHR and/or relatively low other-rated facial attractiveness preferred more "feminine" male faces when choosing faces for a long-term relationship than when choosing for a short-term relationship, possibly reflecting diverse tactics in female mate choice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Regional brain variations of cytochrome oxidase staining during olfactory learning in the honeybee (Apis mellifera).

Regional brain variations of cytochrome oxidase (CO) staining were analyzed in the honeybee (Apis mellifera) after olfactory conditioning of the proboscis extension reflex. Identification of brain sites where stimuli converge was done by precise image analysis performed in antennal lobes (AL) and mushroom bodies (MB). In Experiment 1, bees received 5 odorant stimulations that induced a transient decrease of CO activity in the lateral part of the AL. In Experiment 2, bees were trained with 5-trial olfactory conditioning. CO activity transiently increased in the lips of the MB calyces. There was also a delayed increase in the lateral part of the AL. An olfactory stimulus presented alone and an odor paired to a sucrose stimulation are treated by different pathways, including both AL and MB. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of posture on hand preference during experimental food reaching in bonobos (Pan paniscus).

The effect of posture on hand preferences was examined in an experiment with 5 bonobos (Pan paniscus). To obtain a food reward, the animals had to adopt 1 out of 7 different postures. These postures represented an increasing problem to the maintenance of body equilibrium. It was expected that an increasing demand for equilibrium maintenance would elicit individual preferences and a population-level bias. All animals showed an increasing trend toward left-handedness while shifting to a bipedal posture from a seated posture by way of a quadrupedal posture. The importance of bipedalism in the evolution of left- and right-handedness is discussed briefly. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Flavor preferences in cats (Felis catus and Panthera sp.).

Conducted 4 experiments with 28 domestic and 12 wild cats to examine flavor preference in cats. In the 1st experiment domestic Ss exhibited no preference (both in 24-hr and 1-hr 2-choice preference tests) for any of a variety of carbohydrate or artificial sweeteners regardless of whether a water or saline diluent was employed. A preference for sucrose or lactose dissolved in dilute milk compared with dilute milk alone was observed. This preference may have been based on textural rather than flavor characteristics of the milk-sugar solution. In the 2nd experiment a similar lack of preference for carbohydrate sweeteners was found when using 5-min 2-choice preference tests with wild Ss (genus Panthera). In light of this lack of sweet preference among cats, Exps III and IV examined responses to solutions of hydrolyzed protein and individual amino acids and to emulsified fat mixtures. Solutions of hydrolyzed soy, lactalbumin, and casein; l-alanine and l-proline solutions; and butterfat mixtures were all preferred to the diluent. It is suggested that a pattern of responses characterized by an avidity for protein and fat products and no avidity for carbohydrate sweeteners may be typical of strict carnivores like cats. (21 ref) (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)