What’s in a voice? Dolphins do not use voice cues for individual recognition

Most mammals can accomplish acoustic recognition of other individuals by means of “voice cues,” whereby characteristics of the vocal tract render vocalizations of an individual uniquely identifiable. However, sound production in dolphins takes place in gas-filled nasal sacs that are affected by pressure changes, potentially resulting in a lack of reliable voice cues. It is well known that bottlenose dolphins learn to produce individually distinctive signature whistles for individual recognition, but it is not known whether they may also use voice cues. To investigate this question, we played back non-signature whistles to wild dolphins during brief capture-release events in Sarasota Bay, Florida. We hypothesized that non-signature whistles, which have varied contours that can be shared among individuals, would be recognizable to dolphins only if they contained voice cues. Following established methodology used in two previous sets of playback experiments, we found that dolphins did not respond differentially to non-signature whistles of close relatives versus known unrelated individuals. In contrast, our previous studies showed that in an identical context, dolphins reacted strongly to hearing the signature whistle or even a synthetic version of the signature whistle of a close relative. Thus, we conclude that dolphins likely do not use voice cues to identify individuals. The low reliability of voice cues and the need for individual recognition were likely strong selective forces in the evolution of vocal learning in dolphins.     

Interpersonal aggression and team effectiveness: The mediating role of team goal commitment

This study examines the detrimental effect that interpersonal aggressive behaviours may have on two dimensions of team effectiveness, namely team performance and team viability. Moreover, this study investigates the mediating role of team goal commitment in these relationships. Data were collected from 97 work teams (341 members and 97 immediate supervisors) working in a public safety organization. The results indicate that interpersonal aggression is negatively related to team performance and team viability. The results also show that team goal commitment exercises a complete mediating role with regard to these relationships. Overall, this study highlights potential negative consequences of interpersonal aggression at the team level.     

Religion and the decision to donate organs: Exploring the potential role of religious leaders

The two‐step flow model of communication (Katz, 1957 ) suggests opinion leaders obtain critical information from the mass media and, in turn, communicate this information to interpersonal contacts such as friends, family and co‐workers. It is suggested that religious leaders (RLs) may serve as opinion leaders on the topic of organ donation by debunking donation myths, promoting donation during worship services, or communicating the benefit of donation to families faced with the opportunity to participate in living or cadaveric donation. The current study examined the personal knowledge, experiences, and willingness to communicate about organ donation in a sample of RLs (N = 59) in Rochester, New York. Structured interviews were conducted in summer and fall of 2009 with a random sample of RLs. Results indicate a disparity between RLs' expressed personal support for donation and their engagement in donor registration. Approximately one‐quarter of RLs have spoken about donation during a religious service and many indicate their knowledge is not sufficient to discuss organ donation in detail. Results elaborate on how RLs may be trained to serve as opinion leaders in the promotion of organ donation. Copyright © 2010 John Wiley & Sons, Ltd.     

Perceptual awareness and categorical representation of faces: evidence from masked priming

How internal categories influence how we perceive the world is a fundamental question in cognitive sciences. Yet, the relation between perceptual awareness and perceptual categorization has remained largely uncovered so far. Here, we addressed this question by focusing on face perception during subliminal and conscious perception. We used morphed continua between two face identities and we assessed, through a masked priming paradigm, the perceptual processing of these morphed faces under subliminal and supraliminal conditions. We found that priming from subliminal faces followed linearly the information present in the primes, while priming from visible faces revealed a non-linear profile, indicating a categorical processing of face identities. Our results thus point to a special relation between perceptual awareness and categorical processing of faces, and support the dissociation between two modes of information processing: a subliminal mode involving analog treatment of stimuli information, and a supraliminal mode relying on discrete representation.     

Similarity on the rebound: inhibition of similarity assessment leads to an ironic postsuppressional rebound

A widely held but rarely tested assumption among cognitive scientists is that different cognitive tasks may rely upon a single basic cognitive process. Using an established methodology to examine the suppression and subsequent rebound of mental operations, the present research indicates that suppressing use of similarity in one domain results in the subsequent rebound of similarity assessment in a different domain, suggesting that both domains rely on the same underlying cognitive process. In two studies, we demonstrate that leading people to suppress natural similarity assessment in one task produces increased reliance on similarity in subsequent, different, and apparently unrelated tasks. In Experiment 1, participants led to suppress similarity in a concentration task subsequently made more errors in a false-memory paradigm than did control participants. In Experiment 2, participants suppressing similarity in a categorization task made more false-memory errors and perceived more similarity between word pairs than participants who did not suppress. The findings suggest that the cognitive process of similarity assessment may be a domain-general process, such that it is widespread across a number of different mental tasks.     

The relationship between psychological contract breach and organizational commitment: Exchange imbalance as a moderator of the mediating role of violation

This study tested the mediating role of violation in the relationship between breach and both affective and continuance commitment and the extent to which this mediating role is moderated by exchange imbalance amongst a sample of 103 sales personnel. Results suggest that violation mediated the relationship between breach and commitment. Also, results suggest that perceived exchange imbalance moderates this mediating pathway: Low exchange imbalance increases the mediating role of violation in the case of affective commitment. On the other hand, exchange imbalance failed to moderate the mediating influence of violation in the case of continuance commitment. Results are discussed in view of the importance of a) including both measures of violation and breach in future studies and b) the role of social exchange in explaining psychological contract violation.     

Stimulus range and discontinuity effects on information-integration category learning and generalization

Two studies are reported that support the hypothesis that categories that require a multiple-unit, as opposed to a single-unit, representation lead to worse initial acquisition but better generalization. On the basis of the constraints imposed by the procedural-based learning system thought to mediate information-integration categorization, we argue that the need to train multiple units during initial category acquisition slows the procedural-based category learning process and adversely affects learning performance. However, we speculate that better generalization occurs because of the increased likelihood that a novel stimulus will activate at least one of the multiple units needed to represent the category. Relations to other findings in the literature and the implications of this work for training and clinical assessment are discussed.     

Subjective discriminability of invisibility: A framework for distinguishing perceptual and attentional failures of awareness

Conscious visual perception can fail in many circumstances. However, little is known about the causes and processes leading to failures of visual awareness. In this study, we introduce a new signal detection measure termed subjective discriminability of invisibility (SDI) that allows one to distinguish between subjective blindness due to reduction of sensory signals or to lack of attentional access to sensory signals. The SDI is computed based upon subjective confidence in reporting the absence of a target (i.e., miss and correct rejection trials). Using this new measure, we found that target misses were subjectively indistinguishable from physical absence when contrast reduction, backward masking and flash suppression were used, whereas confidence was appropriately modulated when dual task, attentional blink and spatial uncertainty methods were employed. These results show that failure of visual perception can be identified as either a result of perceptual or attentional blindness depending on the circumstances under which visual awareness was impaired.