Statistical classification of black-capped (Poecile atricapillus) and mountain chickadee (Poecile gambeli) call notes

Both black-capped (Poecile atricapillus) and mountain chickadees (Poecile gambeli) produce a chick-a-dee call that consists of several distinct note types. In some regions, these 2 species live sympatrically, and it has been shown that 1 species will respond weakly to songs of the other. This suggests that chickadee song, and potentially other of their vocalizations, contains species-specific information. We tested the possibility that call notes were acoustically sufficient for species identification. Black-capped and mountain non-D notes were summarized as a set of 9 features and then analyzed by linear discriminant analysis. Linear discriminant analysis was able to use these notes to identify species with 100% accuracy. We repeated this approach, but with black-capped and mountain D notes that were summarized as a set of 4 features. Linear discriminant analysis was able to use these notes to identify species with 94% accuracy. This demonstrates that any of the note types in these chickadee calls possesses sufficient information for species classification.     

Probing the limits of tool competence: Experiments with two non-tool-using species (Cercopithecus aethiops and Saguinus oedipus)

Non-human animals vary in their ability to make and use tools. The goal of the present study was to further explore what, if anything, differs between tool-users and non-tool-users, and whether these differences lie in the conceptual or motor domain. We tested two species that typically do not use tools-cotton top tamarins (Saguinus oedipus) and vervet monkeys (Cercopithecus aethiops)-on problems that mirrored those designed for prolific tool users such as chimpanzees. We trained subjects on a task in which they could choose one of two canes to obtain an out-of-reach food reward. After training, subjects received several variations on the original task, each designed to examine a specific conceptual aspect of the pulling problem previously studied in other tool-using species. Both species recognized that effective pulling tools must be made of rigid materials. Subsequent conditions revealed significant species differences, with vervets outperforming tamarins across many conditions. Vervets, but not tamarins, had some recognition of the relationship between a tool's orientation and the position of the food reward, the relationship between a tool's trajectory and the substance that it moves on, and that tools must be connected in order to work properly. These results provide further evidence that tool-use may derive from domain-general, rather than domain-specific cognitive capacities that evolved for tool use per se.     

Unilateral concessions from the other party: concession behavior, attributions, and negotiation judgments

This article examines the effects of the other party's concession behavior on a negotiator's satisfaction and judgments. The timing of the concessions (immediate, gradual, delayed) and the justifications provided by the other party (negotiator skill vs. external constraints) were manipulated using a scenario method (Study 1) and a role-playing experiment (Study 2). Study 1 showed that concession timing influenced valuation of the object and satisfaction with the partner and the outcome. Justifications about why the concession was made interacted with concession timing to influence participants' attributions. Participants' attributions for why the concession was actually made, in turn, had a main effect on satisfaction and judgments of the negotiation. Study 2 replicated some, but not all, of these findings.     

Gender differences in automatic in-group bias: why do women like women more than men like men?

Four experiments confirmed that women's automatic in-group bias is remarkably stronger than men's and investigated explanations for this sex difference, derived from potential sources of implicit attitudes (L. A. Rudman, 2004). In Experiment 1, only women (not men) showed cognitive balance among in-group bias, identity, and self-esteem (A. G. Greenwald et al., 2002), revealing that men lack a mechanism that bolsters automatic own group preference. Experiments 2 and 3 found pro-female bias to the extent that participants automatically favored their mothers over their fathers or associated male gender with violence, suggesting that maternal bonding and male intimidation influence gender attitudes. Experiment 4 showed that for sexually experienced men, the more positive their attitude was toward sex, the more they implicitly favored women. In concert, the findings help to explain sex differences in automatic in-group bias and underscore the uniqueness of gender for intergroup relations theorists.     

Perceived exertion during resistance exercise by children

This pilot study examined the validity of a new scale of perceived exertion during acute bouts of resistance exercise in young children. The researchers developed an 11-point numerical scale with five pictures representing youths at various levels of exertion while lifting weights. 26 children (M age 10.1 +/- 1.2 yr.) performed one set of 10 repetitions at 35%, 55%, and 75% of their one-repetition maximum on the chest press and leg press exercises using child-size weight training machines. Scaling procedures for the perceptual anchors on the perceived exertion scale were based on one repetition maximum testing. Children could use this scale to translate into numbers their perceptions of physical exertion during upper and lower body resistance exercise. Perceived exertion distributed as a positive linear function of the percent of one repetition maximum on the chest press and leg press exercises (rs = .70 to .77), and perceived exertion increased significantly across all three exercise intensities on both exercises. These preliminary findings provide partial evidence for validation when this scale was used during resistance exercise with children. Additional validation regarding perceived exertion during resistance exercise with children is warranted.     

Auditory-visual interactions in the perception of a ball's path

We carried out two experiments to measure the combined perceptual effect of visual and auditory information on the perception of a moving object's trajectory. All visual stimuli consisted of a perspective rendering of a ball moving in a three-dimensional box. Each video was paired with one of three sound conditions: silence, the sound of a ball rolling, or the sound of a ball hitting the ground. We found that the sound condition influenced whether observers were more likely to perceive the ball as rolling back in depth on the floor of the box or jumping in the frontal plane. In a second experiment we found further evidence that the reported shift in path perception reflects perceptual experience rather than a deliberate decision process. Instead of directly judging the ball's path, observers judged the ball's speed. Speed is an indirect measure of the perceived path because, as a result of the geometry of the box and the viewing angle, a rolling ball would travel a greater distance than a jumping ball in the same time interval. Observers did judge a ball paired with a rolling sound as faster than a ball paired with a jumping sound. This auditory-visual interaction provides an example of a unitary percept arising from multisensory input.     

System-justifying beliefs and psychological well-being: the roles of group status and identity

This research examined the relationship between endorsing system-justifying beliefs and psychological well-being among individuals from ethnic groups that vary in social status. System-justifying beliefs are beliefs that imply that status in society is fair, deserved, and merited; examples of system-justifying beliefs in the United States include the beliefs that hard work pays off and that anyone can get ahead regardless of their group membership. We found that endorsing system-justifying beliefs was negatively related to psychological well-being among members of low-status groups who were highly identified with their group but positively related to well-being among members of low-status groups who were not highly identified with their ethnic group. In addition, we found that endorsing system-justifying beliefs was positively related to well-being among members of high-status groups, especially among members of high-status groups who were highly identified with the group.     

Exploring the role of emotions in injustice perceptions and retaliation

Although organizational justice scholars often describe unfairness as an emotionally laden experience, the role of emotion is underresearched. In a study of individuals who experienced being laid off (N = 173), the authors found that outcome favorability interacts with both procedural and interactional justice to predict participants' emotions. The pattern of interaction differed for inward-focused (i.e., shame and guilt) and outward-focused (i.e., anger and hostility) negative emotions. Attributions of blame mediated the relationship between fairness perceptions and outward-focused negative emotion. Outward-focused emotion mediated the relationship between fairness perceptions and retaliation.     

Acoustic mechanisms of note-type perception in black-capped chickadee (Poecile atricapillus) calls

Acoustic communication in black-capped chickadees (Poecile atricapillus) has been studied intensively, the "chick-a-dee" call being among the most well described. This call consists of 4 note types; chickadees perceive these notes as open-ended categories and do so in a continuous manner, with As more similar to Bs and Bs more similar to Cs. Acoustic features contributing to the note-type differentiation are unknown. Recent analyses suggested that certain acoustic features may play a role in note-type classification. Here, the authors tested black-capped chickadees in an operant-conditioning paradigm to determine which features were controlling note-type perception. The results suggest that the note pitch and the frequency modulation in the initial portion of the note control the perception of note types.