Wild chimpanzees (Pan troglodytes schweinfurthii) distinguish between different scream types: evidence from a playback study

When experiencing aggression from group members, chimpanzees commonly produce screams. These agonistic screams are graded signals and vary acoustically as a function of the severity of aggression the caller is facing. We conducted a series of field playback experiments with a community of wild chimpanzees in the Budongo Forest, Uganda, to determine whether individuals could meaningfully distinguish between screams given in different agonistic contexts. We compared six subjects’ responses to screams given in response to severe and mild aggression. Subjects consistently discriminated between the two scream types. To address the possibility that the response differences were driven directly by the screams’ peripheral acoustic features, rather than any attached social meaning, we also tested the subjects’ responses to tantrum screams. These screams are given by individuals that experienced social frustration, but no physical threat, yet acoustically they are very similar to screams of victims of severe aggression. We found chimpanzees looked longer at severe victim screams than either mild victim screams or tantrum screams. Our results indicate that chimpanzees attend to the informational content of screams and are able to distinguish between different scream variants, which form part of a graded continuum.     

Hazard perception abilities of experienced and novice motorcyclists: An interactive simulator experiment

This study reports an experiment that compared the hazard perception abilities of experienced and novice motorcycle riders using an interactive, closed-loop, simulator. Participants (n = 49) were categorized into four groups: experienced motorcycle riders with full driver licence, inexperienced motorcycle riders with full driver licence, novice motorcycle riders with full driver licence, and novice motorcycle riders with probationary driver licence. The participants were tested on three scenarios, each consisting of eight hazardous events. They were instructed to ride normally, but to respond appropriately to avoid the hazards. Under certain conditions in the simulator, we found that experienced riders (relative to inexperienced or novice riders) crashed less often, received better performance evaluations, and approached hazards at more appropriate speeds. Interestingly, we also found that some novice riders were overconfident in their riding ability. We discuss how this overconfidence might be related to hazard perception.     

The influence of only and even on online semantic interpretation

Focus particles such as only and even indicate that the focused element(s) in a sentence should be contrasted with a set of contextually defined alternatives. Only indicates that properties assigned to the focus set are not shared by elements of the alternative set, whereas even indicates that the focus and alternative sets share the properties mentioned in the sentence. Even has the additional function of marking the focused element as being low on a scale of alternatives ranked in terms of likelihood, thereby signaling that what is being described is somewhat surprising. Using eyetracking, we demonstrate that contrast information associated with only and even is rapidly processed online, with effects for even being delayed, as compared with only (Experiment 1). This difference in time course was not driven by the underlying semantics of the sentence without the focus particle (Experiment 2) but was probably due to even’s more complex semantic function.     

MATHEMATICAL EXPLANATION AND INDISPENSABILITY ARGUMENTS

We defend Joseph Melia's thesis that the role of mathematics in scientific theory is to 'index' quantities, and that even if mathematics is indispensable to scientific explanations of concrete phenomena, it does not explain any of those phenomena. This thesis is defended against objections by Mark Colyvan and Alan Baker.     

Eliciting intelligence from sources informed about counter‐interrogation strategies: An experimental study on the Scharff technique

The Scharff technique aims to elicit information by affecting the source's perception of the interviewer's existing knowledge. Although the technique has been found to be effective for gathering new information, countermeasures to the technique have not been examined. In a 2 × 2 between‐subjects experiment, we informed half of the 120 sources about the counter‐interrogation strategy of carefully considering the interviewer's prior knowledge and the tactic of providing information perceived as already known to the interviewer. After this, sources were interviewed with the Scharff technique or the Direct approach, widely used in human intelligence‐gathering situations and consisting of open‐ended and direct questions. We found that “informed sources” did not succeed in revealing information already known to the interviewer, where informed sources and uninformed sources revealed known information to a similar degree (1.62 pieces vs. 1.65 pieces). Sources interviewed with the Direct approach (vs. Scharff technique) revealed a larger amount of information previously known to the interviewer (2.18 pieces vs. 1.08 pieces). When interviewed with the Scharff technique, sources informed about the counter‐interrogation strategy attempted to adopt more counter‐interrogation strategies. The present study replicates earlier research on the Scharff technique as a technique effective in affecting the source's perception of the interviewer's prior knowledge. The results of the current study indicate that both the Scharff technique and the Direct approach might be similarly robust against counter‐interrogation strategies, in terms of gathering new information. Future studies should focus on implementing more comprehensive training in counter‐interrogation strategies for the sources.     

A manifesto for the new MCDA era

The following manifesto has been prepared by five prominent workers in the field of MCDA. We are currently preparing a special issue on the issues that they raise (see Call for Papers on p. 128). We invite you to contribute to the debate in that issue, either in the form of a paper or a letter to the Editor.     

Valuing the future: a MADA example involving nuclear waste storage

Intertemporal decision making involves decisions that have consequences that span several periods of time and often extend far into the future. The purpose of this paper is to discuss and highlight the differences associated with different evaluation methods designed to cope with the long-term impacts of a decision including discounting. The concepts and ideas are illustrated in the context of a decision about a nuclear waste facility. We show how applying different discounting methodologies can greatly affect the decision made, especially over long time periods. © 1998 John Wiley & Sons, Ltd.     

From landsmanshaften to vinkln: Mediating community among Yiddish speakers in America

Vinkln (“corners”) in America have spread since the 1970s as an organizational strategy by Yiddish-speaking, non-pietistic, East European Jewish immigrants, many of whom have a Holocaust experience. The vinkln provide a privatized, immersive experience for Yiddish language and culture as a way to offer community identity to Yiddish speakers within the wider Jewish community. They arose out of landsmanschaften, or “hometown associations,” in the early twentieth century, but the vinkln function to ritually reproduce culture rather than offer mutual aid based on old-country affiliation. Although secularized, the organized social structure and performed communication of the vinkln invoke rituals and roles of Jewish religious services from traditional community experience. They displace old-country affiliations with pronounced loyalties to Israel and America, although the location of Yiddish in performance is often centered in Poland. The vinkln mediate community by suggesting cultural reproduction even as the bonds of language and society among Yiddish speakers are weakening. Its symbols and associations are restricted to an elderly age cohort, and therefore not likely to perpetuate the very culture that its organizers purport to preserve. It is differentiated from other structures of Yiddish conservation and appreciation such as Internet networks and community center conversation groups. This revised version was published online in June 2006 with corrections to the Cover Date.