Responses to olfactory stimuli in spotted hyenas (Crocuta crocuta): I. Investigation of environmental odors and the function of rolling

Olfaction is crucial to spotted hyenas (Crocuta crocuta), yet there are no controlled studies of their reactions to odors. In Experiment 1, the authors examined responses of captive hyenas to various environmental (prey, nonprey animal, and plant) odors. Subjects approached and sniffed all odors equally but preferentially licked prey odors, scent marked next to odors, and rolled in animal-based odors. In Experiment 2, the authors examined the function of rolling by applying odors to the pelts of captive hyenas. When hyenas wore carrion, they gained positive social attention (increased investigation and allogrooming) from pen mates, but when they wore camphor, the normal social greeting ceremony was curtailed. Thus, olfactory stimuli elicit specific responses, influence where behavior is directed, and can be used to affect social interaction.     

Scent marking (pasting) in a colony of immature spotted hyenas (Crocuta crocuta): a developmental study

Pasting, a stereotypic form of anal gland scent marking, was studied in 2 cohorts (N = 20) of captive spotted hyenas (Crocuta crocuta). A significant increment in the frequency of pasting occurred in both cohorts as the animals approached sexual maturity; however, gonadectomy during the early juvenile age period had no significant effects on subsequent pasting frequency. Dominant hyenas in both cohorts tended to scent-mark more frequently than subordinates during the late subadult period. Pasting was facilitated by the immediately preceding pasting activities of other hyenas, as has been reported to occur in nature, and olfactory investigation was the most common behavior preceding pasting.     

Olfactory recognition of individual competitors by means of faeces in horse (<Emphasis Type="Italic">Equus caballus</Emphasis>)

Living in complex social systems requires perceptual and cognitive capacities for the recognition of group membership and individual competitors. Olfaction is one means by which this can be achieved. Many animals can identify individual proteins in urine, skin secretions, or saliva by scent. Additionally, marking behaviour in several mammals and especially in horses indicates the importance of sniffing conspecifics’ faeces for olfactory recognition. To test this hypothesis, we conducted two separate experiments: Experiment 1 addressed the question of whether horses can recognise the group membership of other horses by sniffing their faeces. The horses were presented with four faecal samples: (1) their own, (2) those of other members of their own group, (3) those of unfamiliar mares, and (4) those of unfamiliar geldings. Experiment two was designed to assess whether horses can identify the group member from whom a faecal sample came. Here, we presented two groups of horses with faecal samples from their group mates in random distribution. As controls, soil heaps and sheep faecal samples were used. In experiment one, horses distinguished their own from their conspecifics’ faeces, but did not differentiate between familiarity and sex. In experiment two, the horses from both groups paid most attention to the faeces of the horses from which they received the highest amount of aggressive behaviours. We therefore suggest that horses of both sexes can distinguish individual competitors among their group mates by the smell of their faeces.     

Environmental influences on flank marking and urine marking by female and male rats (Rattus norvegicus)

Sprague-Dawley rats (Rattus norvegicus) were observed in a familiar environment. In Experiment 1 a leader entered a clean chamber, and an opposite-sex follower entered the chamber next. Both sexes began to flank mark after several sessions. Males flank marked more, and females locomoted more, but both sexes urine marked and investigated objects equally often. Leaders and followers did not differ on any measure. In Experiment 2 we measured floor marks more precisely and manipulated the number of objects and the presence of scent marks. Flank marking was more frequent in the presence of conspecific urine but did not vary with the number of objects or the sex of the rats. More objects elicited more investigating and urine marking and produced fewer floor marks but increased the number of marks in the central area in relation to the periphery. The results indicate that rats' flank marking is behaviorally distinct from urine marking and differentially affected by environmental variables.     

Ventral scent marking in Meriones unguiculatus may contribute to thermoregulation

Three experiments were conducted with adult male Meriones unguiculatus in an attempt to demonstrate that ventral scent marking can act to transfer body heat to the object marked. Experiment 1 showed that surgical removal of the ventral gland pad reduced the amount of heat transferred by 50%, even though intact and glandless animals did not differ in the average frequency of scent marking. Experiment 2 demonstrated that the difference in heat transfer due to the presence or absence of the scent pad was not due to differential pressure applied to the substrate during marking. Experiment 3 showed that the pattern of ventral hair spread that occurs as an animal moves over an object is different between intact and glandless animals but that this difference does not account for the difference in heat transfer. It is suggested that heat transfer to the environment with ventral scent marking may increase thermoregulatory competence and also may function to volatilize sebum used in chemocommunication.     

Using prior knowledge to minimize interference when learning large amounts of information

In three experiments, we examined mediated learning in situations involving learning a large amount of information. Participants learned 144 "facts" during a learning phase and were tested on facts during a test phase. In Experiments 1 and 2, participants learned facts about familiar individuals, unfamiliar individuals, or unfamiliar individuals associated with familiar individuals. Prior knowledge reduced interference, even when it played only a mediating role. In Experiment 3, participants learned facts about unfamiliar individuals or unfamiliar countries, with half the participants in each group associating the unfamiliar items with familiar individuals. Again, use of prior knowledge to mediate learning reduced interference even when the new information was conceptually dissimilar to the previously known information. These results are consistent with the mental model account of long-term memory.     

Going With the Flow: Preschoolers Prefer Nondissenters as Informants

ABSTRACT— In two experiments, 3- and 4-year-olds were tested for their sensitivity to agreement and disagreement among informants. In pretest trials, they watched as three of four informants ( Experiment 1 ) or two of three informants ( Experiment 2 ) indicated the same referent for an unfamiliar label; the remaining informant was a lone dissenter who indicated a different referent. Asked for their own judgment, the preschoolers sided with the majority rather than the dissenter. In subsequent test trials, one member of the majority and the dissenter remained present and continued to provide conflicting information about the names of unfamiliar objects. Children remained mistrustful of the dissenter. They preferred to seek and endorse information from the informant who had belonged to the majority. The implications and scope of children's early sensitivity to group consensus are discussed.     

Artifacts and natural kinds: children's judgments about whether objects are owned

People's behavior in relation to objects depends on whether they are owned. But how do people judge whether objects are owned? We propose that people expect human-made objects (artifacts) to be more likely to be owned than naturally occurring objects (natural kinds), and we examine the development of these expectations in young children. Experiment 1 found that when shown pictures of familiar kinds of objects, 3-year-olds expected artifacts to be owned and inanimate natural kinds to be non-owned. In Experiments 2A and 2B, 3-6-year-olds likewise had different expectations about the ownership of unfamiliar artifacts and natural kinds. Children at all ages viewed unfamiliar natural kinds as non-owned, but children younger than 6 years of age only endorsed artifacts as owned at chance rates. In Experiment 3, children saw the same pictures but were also told whether objects were human-made. With this information provided, even 3-year-olds viewed unfamiliar artifacts as owned. Finally, in Experiment 4, 4- and 5-year-olds chose unfamiliar artifacts over natural kinds when judging which object in a pair belongs to a person, but not when judging which the person prefers. These experiments provide first evidence about how children judge whether objects are owned. In contrast to claims that children think about natural kinds as being similar to artifacts, the current findings reveal that children have differing expectations about whether they are owned.     

Flying to Neverland: How readers tacitly judge norms during comprehension

As readers gain experience with specific narrative worlds, they accumulate information that allows them to experience events as normal or unusual within those worlds. In this article, we contrast two accounts for how readers access information about specific narrative worlds to make tacit judgments of normalcy. We conducted two experiments. In Experiment 1, participants read stories about an ordinary character (e.g., a police officer in Boston) or a familiar fantastic character (e.g., Superman). Each story described a realistic event (e.g., the character being killed by bullets) or a fantastic event (e.g., bullets bouncing off the character’s chest). Participants were faster to read events that were consistent with their prior knowledge about the story world. In Experiments 2a and 2b, participants read stories about familiar fantastic characters, unfamiliar fantastic characters (e.g., a Kryptonian named Dev-em), and unfamiliar ordinary characters. In Experiment 2a, participants were equally fast to read about the familiar and unfamiliar fantastic characters experiencing fantastic events, both of which were read faster than the unfamiliar ordinary characters sentences. In Experiment 2b, participants were fastest to read about unfamiliar ordinary characters experiencing realistic events and were equally slow for familiar and unfamiliar fantastic characters. Our experiments provide evidence that readers routinely use inductive reasoning to go beyond their prior knowledge when reading fictional narratives, affecting whether they experience events as normal or unusual.     

Visual detection of multi-letter patterns

This study addressed two basic questions about the detection of multi-letter patterns: (a) How is the detection of a multi-letter pattern related to the detection of its individual components? (b) How is the detection of a sequence of letters influenced by the observer's familiarity with that sequence? In three experiments observers searched for one-, two-, or three letter patterns embedded in a rapid series of multiple six-letter frames. In Experiment 1, unfamiliar two-letter patterns were detected more accurately than their one-letter components. This two-letter advantage reflects the fact that in an array of fixed size, larger target stimuli contain more information and are easier to discriminate from nontarget alternatives. Quantitative analyses indicated that observers combine information not decisions, about the component letters in a pattern. In Experiment 2, with statistical and physical properties equated, a familiar three-letter pattern (i.e., CAT) was detected more accurately than its unfamiliar anagram (i.e., TCA). This word advantage in word (not letter) detection persisted even after extensive practice and was uninfluenced by the lexical character of distractor items. In Experiment 3, words (e.g., FIB), pronounceable non words (e.g., FIF(, and familiar acronyms (e.g., FBI) were detected more readily than unfamiliar items (e.g., IBF). Thus both orthographic knowledge and familiarity with specific sequences can facilitate perceptual processing in "word" detection.     

Population growth and social structure of confined colonies of mongolian gerbils: Scent gland size and marking behaviour as indices of social status

Male gerbils have larger ventral scent glands, and they mark more than females. In both sexes, scent gland activity is dependent on gonadal hormones. Observations on colonies of gerbils, living in enclosures or cages, showed that both scent gland size and marking behaviour were related to social status. In colonies founded by a single pair, breeding was confined to the original female. The infertility of the daughters was due to failure of sexual maturation. As this was always associated with a lack of development of the scent glands, the functional state of the latter could be used as an index of fecundity. A change in social organization (eg removal of the parents) caused previously infertile females to conceive and was accompanied by development of the scent glands If there was competition for dominance, the scent glands of the losers regressed; at autopsy, their ovaries and uteri appeared to be nonfunctional. The founding father usually had a larger scent gland than his sons, but the inhibition of sexual function was not as severe as in the females. However, the father characteristically showed much more marking behaviow in a neutral territory than his sons. None of the fem ales-except the mother-showed appreciable marking, and her scores were much lower than those of the dominant male. Asymptotic populations were reached at about the same level in enclosures and cages, implicating an intrinsic capacity for control independent of the number of animals per unit of space but probably related to the natural size of a social group. Stabilization of numbers was achieved not only by reproductive inhibition of young females, but also by cessation of breeding by the founding mother and death of litters. Littermates raised in enclosures without their parents showed delayed sexual maturation accompanied by fighting which resulted in the formation of a hierarchy headed by a breeding female and a dominant (marking) male.     

Does contingency in adults’ responding influence 12-month-old infants’ social referencing?

In two experiments we examined the influence of contingent versus non-contingent responding on infant social referencing behavior. EXPERIMENT 1: Forty 12-month-old infants were exposed to an ambiguous toy in a social referencing situation. In one condition an unfamiliar adult who in a previous play situation had responded contingently to the infant’s looks gave the infant positive information about the toy. In the other condition an unfamiliar adult who previously had not responded contingently delivered the positive information. EXPERIMENT 2: Forty-eight 12-month-old infants participated in Experiment 2. In this experiment it was examined whether the familiarity of the adult influences infants’ reactions to contingency in responding. In one condition a parent who previously had responded contingently to the infant’s looks provided positive information about the ambiguous toy, and in the other condition a parent who previously had not responded contingently provided the positive information. The infants looked more at the contingent experimenter in Experimenter 1, and also played more with the toy after receiving positive information from the contingent experimenter. No differences in looking at the parent and in playing with the toy were found in Experiment 2. The results indicate that contingency in responding, as well as the familiarity of the adult, influence infants’ social referencing behavior.     

Does contingency in adults’ responding influence 12-month-old infants’ social referencing?

In two experiments we examined the influence of contingent versus non-contingent responding on infant social referencing behavior. EXPERIMENT 1: Forty 12-month-old infants were exposed to an ambiguous toy in a social referencing situation. In one condition an unfamiliar adult who in a previous play situation had responded contingently to the infant’s looks gave the infant positive information about the toy. In the other condition an unfamiliar adult who previously had not responded contingently delivered the positive information. EXPERIMENT 2: Forty-eight 12-month-old infants participated in Experiment 2. In this experiment it was examined whether the familiarity of the adult influences infants’ reactions to contingency in responding. In one condition a parent who previously had responded contingently to the infant’s looks provided positive information about the ambiguous toy, and in the other condition a parent who previously had not responded contingently provided the positive information. The infants looked more at the contingent experimenter in Experimenter 1, and also played more with the toy after receiving positive information from the contingent experimenter. No differences in looking at the parent and in playing with the toy were found in Experiment 2. The results indicate that contingency in responding, as well as the familiarity of the adult, influence infants’ social referencing behavior.     

Conceptual and physical object qualities contribute differently to motor affordances

Priming studies have demonstrated that an object’s intrinsic and extrinsic qualities (size, orientation) influence subsequent motor behavior thus suggesting that these object qualities ‘afford’ actions that are congruent with the prime. We present four experiments that aim to evaluate the relative effect of conceptual and physical object qualities on action priming. In Experiment 1 equally graspable known and unknown tools are presented as primes. In Experiment 2 the primes depict high versus low graspable unfamiliar tools, and in Experiments 3 and 4 we present simple graspable shapes versus high graspable unfamiliar or familiar tools respectively. In all experiments the (unrelated) task consists of a timed motor response to the direction of a centrally placed arrow that is superimposed on the prime. Whereas tool familiarity reveals no significant difference on reaction time (Exp 1), responses to high graspable unfamiliar tools (Exp 2) and simple graspable shapes (Exps 3 and 4) are significantly faster. We conclude that motor affordances are most readily determined by object qualities that depend on the object’s physical appearance provided by visual information. Conceptual information about the stimuli, such as semantic category or stored knowledge about its function and associated movements, does not appear to produce detectable effects of action priming in this paradigm.     

不同目标标记方式对多目标追踪表现的影响

有关多目标追踪的研究多采用目标闪烁数次或目标周围出现方框等视觉方式对目标进行标记。在已有研究基础上,通过2个实验比较了不同目标数量下视觉平行标记、视觉序列标记、听觉序列标记(视听跨通道标记)和视听双通道序列标记4种目标标记方式对多目标追踪表现的影响。研究结果表明在多目标追踪任务中,线索阶段目标的视觉标记比视听跨通道标记更有效,且不受目标的序列标记或平行标记的影响,而视觉和听觉编码结合（视听双通道标记）可以促进任务难度较高时的追踪表现。     

The Effect of Language-Specific Characteristics on English and Japanese Speakers' Ability to Recall Number Information

The current paper presents two experiments investigating the effect of presence versus absence of compulsory number marking in a native language on a speaker's ability to recall number information from photos. In Experiment 1, monolingual English and Japanese adults were shown a sequence of 110 photos after which they were asked questions about the photos. We found that the English participants showed a significantly higher accuracy rate for questions testing recall for number information when the correct answer was “2” (instead of “1”) than Japanese participants. In Experiment 2, English and Japanese adults engaged in the same task as in Experiment 1 with an addition that explored reasons for the results found in Experiment 1. The results of Experiment 2 were in line with the results of Experiment 1, but also suggested that the results could not be attributed to differences in guessing patterns between the two groups or the type of linguistic constructions used in the test situations. The current study suggests that native language affects speakers' ability to recall number information from scenes and thus provides evidence for the Whorfian hypothesis.     

Memory for details about people: familiarity,relatedness, and gender congruency

This study examines factors that influence memory for details about people. In two experiments, subjects learned fictitious details about familiar (friends, relatives) and/or unfamiliar individuals, and were tested both immediately and after a 1-week delay. To control for a confounding between familiarity and genetic relatedness in Experiment 1, in Experiment 2 specific relationships (identical twin, first cousin, acquaintance) were assigned to unfamiliar individuals. Across experiments, retention was enhanced for familiar compared to unfamiliar individuals, for friends/acquaintances compared to relatives, for more closely than distantly related individuals, and for individuals of the opposite gender as the subject.     

Familiarity and person construal: Individuating knowledge moderates the automaticity of category activation

In this experiment, we examined how perceivers' familiarity with targets moderates person construal. Based on evidence from object categorization that level of construal varies with expertise in a manner that maximizes cue validity, we reasoned that although social (i.e., group‐level) categorization is functional for construing unfamiliar others (about whom little or no individuating information is available), it is less functional for familiar others (about whom a great deal of individuating information is available). Results from an automatic priming paradigm provided evidence for our reasoning: Participants categorized unfamiliar faces according to the most salient categorical dimension available in the visual information (in this case, sex), but did not do so for familiar faces. Implications for models of person perception are discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

Understanding the abstract role of speech in communication at 12 months

Adult humans recognize that even unfamiliar speech can communicate information between third parties, demonstrating an ability to separate communicative function from linguistic content. We examined whether 12-month-old infants understand that speech can communicate before they understand the meanings of specific words. Specifically, we test the understanding that speech permits the transfer of information about a Communicator's target object to a Recipient. Initially, the Communicator selectively grasped one of two objects. In test, the Communicator could no longer reach the objects. She then turned to the Recipient and produced speech (a nonsense word) or non-speech (coughing). Infants looked longer when the Recipient selected the non-target than the target object when the Communicator had produced speech but not coughing (Experiment 1). Looking time patterns differed from the speech condition when the Recipient rather than the Communicator produced the speech (Experiment 2), and when the Communicator produced a positive emotional vocalization (Experiment 3), but did not differ when the Recipient had previously received information about the target by watching the Communicator's selective grasping (Experiment 4). Thus infants understand the information-transferring properties of speech and recognize some of the conditions under which others' information states can be updated. These results suggest that infants possess an abstract understanding of the communicative function of speech, providing an important potential mechanism for language and knowledge acquisition.     

The rate of scent marking by male rats and consequent olfactory preferences of female rats

An experiment is reported designed to test the hypothesis that female rats might discriminate between males that differed in the quantity of odor deposited by scent marking. Male odor donors were selected by prior screening for high or low rates of scent marking in an open arena. Females were then tested to determine whether they showed any preference for males that marked at a high rate. It was found that female rats did discriminate, but that they preferred to remain near males selected for low rates of scent marking.