Bitter avoidance in guinea pigs (Cavia porcellus) and mice (Mus musculus and Peromyscus leucopus)

Rejection of bitter substances is common in many species and may function to protect an animal from ingestion of bitter-tasting toxins. Since many plants are bitter, it has been proposed that high tolerance for bitterness would be adaptive for herbivores. Earlier studies conducted on herbivorous guinea pigs (Cavia porcellus) have been used to support this proposal. We tested guinea pigs with bitter plant secondary metabolites (salicin, caffeine, quinine hydrochloride) and bitter protein hydrolysates (two types of hydrolyzed casein, hydrolyzed soy) in a series of two-choice preference tests. For comparison, we tested two nonherbivorous mouse species (Mus musculus and Peromyscus leucopus). Guinea pigs did show weaker avoidance of quinine hydrochloride than did the mice, confirming predictions generated from earlier work. However, guinea pigs had similar responses to caffeine as did Peromyscus. Both of these species showed weaker avoidance responses than Mus to 10 mM caffeine. For salicin, guinea pigs were the only species to avoid it at 10 mM and their preference scores at this concentration were significantly lower than for the two mice species. Guinea pigs avoided all of the protein hydrolysates more strongly than the other species. Responses to the protein hydrolysates did not reflect the patterns observed with the simple bitter compounds, suggesting that other properties of these complex stimuli may be responsible for guinea pig avoidance of them. Our results suggest caution in accepting, without further empirical support, the premise that guinea pigs (and herbivores in general) have a generalized reduced bitter sensitivity.     

Auditory spatial responses of young guinea pigs (Cavia porcellus) during and after ear blocking

Newborn guinea pigs were tested to determine their ability to approach an auditory stimulus early in development. Observations of the behavior of 1-4-day-old animals in a circular eight-choice maze revealed a pronounced tendency to orient toward and approach a tape-recorded signal of guinea pig vocalizations. The occurrence of approach responses was reduced to chance in animals tested with one ear occluded by wax ear plugs which attenuated but did not totally eliminate sound. The effect of monaural ear blocks was more severe than binaural blocks, which reflects the importance of binaural cues in the maintenance of approach responses to sound. In a second study, the ability of older animals, 11-31 days of age, was examined. Directional approach responses to sound were also evident at this age, and ear plugs disrupted performance only under monaural conditions. Furthermore, in animals raised from birth with monaural ear blocks but tested without ear plugs, there was a subsequent disruption of performance for at least 21 days. These results indicate the importance of binaural cues in the development of early auditory spatial responses and suggest the need for appropriate binaural experience for subsequent localization of sounds.     

Social preferences of developing guinea pigs (Cavia porcellus) from the preweaning to the periadolescent periods

Preference tests in a novel environment (Experiment 1) and unobtrusive observations in a specialized living environment (Experiment 2) examined the attractiveness of various classes of conspecifics for maturing guinea pigs (Cavia porcellus). It was found that (a). the young continued to remain near the mother well beyond weaning; (b). there was increased time spent with unrelated adult females, but not males, after weaning; (c). male and female offspring behaved similarly; and (d). littermates spent considerable time with each other. These results provide no evidence that guinea pigs approaching sexual maturity begin to associate preferentially with novel animals or potential breeding partners. Choices were largely predictable from earlier findings of the ability of various classes of conspecifics to reduce hypothalamic-pituitary-adrenal activity of the young.     

Development and control of licking in the guinea pig (Cavia porcellus)

Guinea pigs were taught to lick an electronic lickometer by successive approximations brought about by a gradually receding lickerandum-liquid feeder mounted in their home cage. All Ss learned to lick and obtain their total liquid intake by tongue licking. An optimum deprivation schedule was determined, and the response was brought under schedule control comparable to that of the rat.     

Light-dark variation and changes across the lactational period in the behaviors of undisturbed mother and infant guinea pigs (Cavia porcellus)

Lactating guinea pigs (Cavia porcellus) and their litters were observed by videophotography across the light/dark cycle at 1, 11, 21, and 31 days postpartum. The highest level of behavioral activity was seen in the dark, particularly in the hour after light offset. This circadian pattern was evident from Day 1 in mothers and from Day 11 in pups. Contact between mothers and pups was inversely related to activity, occurring more frequently during light. Maternal grooming of pups occurred on Day 1 and then declined: self-grooming by pups increased across days. Intake of solid food and water by pups occurred on Day 1 and increased thereafter. A nearly complete transition from nursing to independent ingestion was observed between 21-31 days of age. Overall, we document several ontogenetic changes in young guinea pigs and demonstrate that under laboratory conditions mother and infant guinea pigs exhibit a nocturnal activity pattern.     

Rehousing periadolescent male guinea pigs (Cavia porcellus) apart from their mothers for 24 hours increases maternally directed sexual behavior and plasma testosterone

Periadolescent male guinea pigs (Cavia porcellus) housed continuously with their mother displayed little or no sexual behavior when they were tested with her in a novel environment. However, if males were rehoused without their mother for 24 hr before testing, they frequently directed courtship and sexual behavior toward her. This effect occurred whether the mother was isolated or not during the rehousing period. In addition, rehousing without the mother produced a significant rise in the plasma testosterone levels of the males. It appears that continuous housing with the mother inhibits sexual and courtship behavior directed toward her, as well as gonadal activity, in periadolescent male guinea pigs. These effects may serve to prevent inbreeding.     

Effects of olfactory bulbectomy on social behavior of male guinea pigs (Cavia procellus)

Effects of olfactory bulbectomy on social behavior in male guinea pigs were studied. Both brief-exposure pairing techniques and a group-living observation period were employed to test for disruption. During short-term testing sessions bulbectomized animals courted females less than but mounted them as frequently as control subjects. While the groups did not differ in fighting behavior during short-term tests, control subjects scent-marked more frequently. Subsequently, animals were observed as same-treatment pairs living continuously with females, and behavior was sampled over a 3-wk period. Under these conditions bulbectomized males, unlike controls, failed to form dominance orders, exhibited virtually no intermale aggressive activity, had markedly depressed sexual activity, and scent-marked rarely. It is concluded that olfactory bulbectomy profoundly alters the behavior of male domestic guinea pigs and that hose alterations are most evident when experimental subjects are observed in a species-typical group-living environment.     

Motivated behaviors elicited from hypothalamus, midbrain, and pons of the guinea pig (Cavia porcellus).

Eating, drinking, biting attack, male mating behavior, and gnawing were elicited by electrical stimulation through electrodes located predominantly in a region extending from the preoptic area through the lateral hypothalamus into the ventral midbrain. Escape and digging were elicited from a parallel but more medial region that overlapped the lateral zone only in the preoptic-anterior hypothalamic area. Several differentiable vocalizations were produced from sites distributed through most, although not all, areas explored. Sites yielding painlike responses were located principally in the vicinity of the presumed pain pathway traced after anterolateral cordotomy in other species. Reward was obtained from widespread sites that were generally congruent with catecholaminergic systems as described in the rat. Although there was considerable overlap of the effective zones for many responses, their underlying mechanisms were differentiated anatomically by localized differences in their distribution or functionally by the elicitation of pure responses from some electrodes. Response mechanisms localized in the brain stem of the guinea pig generally resembled those in the rat, although there were differences in details, especially in the posterior midbrain and pons.     

Social organization predicts nature of infant-adult interactions in two species of wild guinea pigs (Cavia aperea and Galea monasteriensis)

The authors compared interactions of infants with mothers and unfamiliar females in a novel environment in 2 caviomorph rodent species: the harem-living Cavia aperea, the probable progenitor of the domestic guinea pig; and the pair-living Galea monasteriensis. In C. aperea, interactions with mothers and unfamiliar females were largely similar; in G. monasteriensis, interactions with the mother, but not unfamiliar female, were characterized by physical closeness and sociopositive behavior. In G. monasteriensis, plasma cortisol levels were lower when with the mother than when with the unfamiliar female. Results are consistent with the species' social organizations and suggest that behavioral interactions of pups with mothers and other females in domestic guinea pigs reflect primarily the social organization of the progenitor species rather than domestication.     

Increases in parental investment and child health as a result of an early intervention

Parental investment (involving time or money invested in 3-year-olds) and child health were assessed as an outcome of (a) children’s risk status (preterm vs. full-term birth) and (b) maternal resources (defined here in terms of their problem-solving skills in resolving caregiving challenges). Resources were varied systematically as a function of maternal participation in a traditional home visitation program versus a novel cognitively enhanced program that facilitated parenting skills more successfully. As predicted, mothers in the traditional home visitation condition invested preferentially in low-risk children, whereas mothers in the cognitively enhanced condition invested preferentially in high-risk children (who, in turn, showed maximal health benefits). Maternal investment of time in care provision mediated the relationship between predictor variables and children’s health. This pattern supports an evolutionary model of parental investment in which parents show discriminative solicitude based on the reproductive potential of the child and parents’ access to relevant resources.     

Gender differences in mate selection preferences: a test of the parental investment model.

Evolutionary-related hypotheses about gender differences in mate selection preferences were derived from Triver's parental investment model, which contends that women are more likely than men to seek a mate who possesses nonphysical characteristics that maximize the survival or reproductive prospects of their offspring, and were examined in a meta-analysis of mate selection research (questionnaire studies, analyses of personal advertisements). As predicted, women accorded more weight than men to socioeconomic status, ambitiousness, character, and intelligence, and the largest gender differences were observed for cues to resource acquisition (status, ambitiousness). Also as predicted, gender differences were not found in preferences for characteristics unrelated to progeny survival (sense of humor, "personality"). Where valid comparisons could be made, the findings were generally invariant across generations, cultures, and research paradigms.     

Family Assessment Measure (FAM) and Process Model of Family Functioning

This paper provides an overview of twenty years' work in the development of the Family Assessment Measure (FAM), based on the Process Model of Family Functioning. The Process Model describes a conceptual framework for conducting family assessments according to seven key dimensions: task accomplishment, role performance, communication, affective expression, involvement, control, values and norms. The FAM provides measures of these dimensions at three levels: whole family system (general scale, fifty items), various dyadic relationships (dyadic scale, forty-two items) and individual functioning (self-rating scale, forty-two items). In addition, the general scale includes social desirability and defensiveness response style measures. Brief FAMs (fourteen items) are available for each scale as well. The measurement properties of FAM have been evaluated in a variety of clinical and non-clinical settings. Reliability estimates are very good in most contexts. FAM's validity has been supported using a number of techniques. Overall, the weight of the evidence is that FAM's effectively and efficiently assess family functioning and provide strong explanatory and predictive utility. This empirical evidence reinforces experiences of clinicians, indicating that FAM provides a rich source of information on family functioning.     

Conscious awareness of methodological choices: A reply to Milberg and McGlinchey (2010)

Milberg and McGlinchey (2010) claim that the conclusions we reach in "Perceptual Grouping Operates Independently of Attentional Selection: Evidence From Hemispatial Neglect" are unwarranted. Specifically, it is asserted that insufficient methodological control was exerted over the attentional status of the patients and that partial attention to the contralesional field could have resulted in the congruency effects we observe. Although we agree with their methodological cautions in general, we argue that our investigation is, in fact, methodologically sound. In particular, we reiterate and highlight that our investigation is unprecedented in the characterization of a patient sample with multiple clinical, psychophysical, and experimental measures; in our use of a stringent, rigidly controlled paradigm specifically designed for investigating perceptual grouping without awareness; in our modification of the experimental procedure to make it even more stringent; and in our specific methodological choices for comparison/control conditions within this experimental paradigm. We also demonstrate that partial attention to the contralesional left cannot support the robust congruency effects we observe. In light of this, we remain confident of our interpretation of our findings and suggest that perceptual grouping can indeed operate in the absence of attention.     

Offence and defence in fights between young pigs (Sus scrofa)

Fights were observed between young, unacquainted, domestic pigs. These fights were described in terms of the frequency of bites and the time spent in each of five spatial configurations of the animals. Depending on the rate that bites were given or received, each spatial configuration was characterized as resulting from offence or defence by one of the pigs. Bites were mainly directed at the head and ears, and defensive moves placed these areas out of reach. The most effective offensive move was an attack from the side. Pigs that lost fights tended to turn away from such attacks: winners were as likely to turn towards the attacker. Whether turning away is submission or simply defence is not clear. Factor analysis showed that fights could be described on three dimensions: offence by the loser along with mutual offence and mutual defence: offence by the winner and defence by the loser: and defence by the winner. Long fights involved much offence by the loser and defence by the winner: short fights involved much defence by the loser. When the pigs met again after 24 h, the fights were shorter and involved less offence and more defence by the loser. The transitions between the configurations reflect a balance of offence and defence by the pig responsible making for the transition. This balance is, in turn, affected by attacks from the opponent, fatigue, and the pig's assessment of its relative fighting ability. Retaliation against attacks is partly responsible for the persistence of fighting.