No Evidence of Suicide Increase Following Terrorist Attacks in the United States: An Interrupted Time‐Series Analysis of September 11 and Oklahoma City

There is substantial evidence of detrimental psychological sequelae following disasters, including terrorist attacks. The effect of these events on extreme responses such as suicide, however, is unclear. We tested competing hypotheses about such effects by employing autoregressive integrated moving average techniques to model the impact of September 11 and the Oklahoma City bombing on monthly suicide counts at the local, state, and national level. Unlike prior studies that provided conflicting evidence, rigorous time series techniques revealed no support for an increase or decrease in suicides following these events. We conclude that while terrorist attacks produce subsequent psychological morbidity and may affect self and collective efficacy well beyond their immediate impact, these effects are not strong enough to influence levels of suicide mortality.     

Effects of Visual Representation on Social Influence in Computer‐Mediated Communication

Two experiments investigated if and how visual representation of interactants affects depersonalization and conformity to group norms in anonymous computer‐mediated communication (CMC). In Experiment 1, a 2 (intergroup versus interpersonal) × 2 (same character versus different character) between‐subjects design experiment (N= 60), each participant made a decision about social dilemmas after seeing two other (ostensible) participants’ unanimous opinions and then exchanged supporting arguments. Consistent with the Social Identity model of Deindividuation Effects (SIDE), when the group level of self‐identity was rendered salient in an intergroup encounter, uniform virtual appearance of CMC partners triggered depersonalization and subsequent conformity behavior. By contrast, when the personal dimension of the self was salient, standardized representation tended to reduce conformity. To elucidate the mediation process, Experiment 2 investigated the causal links between depersonalization, group identification, and conformity. The results show that depersonalization accentuated adherence to group norms, both directly and indirectly via group identification.     

The Multiple Source Effect and Synthesized Speech

Two experiments examine the effect of multiple synthetic voices in an e‐commerce context. In Study 1, participants (N= 40) heard five positive reviews about a book from five different synthetic voices or from a single synthetic voice. Consistent with the multiple source effect, results showed that participants hearing multiple synthetic voices evaluated the reviewed books more positively, predicted more favorable public reaction to the books, and felt greater social presence of virtual speakers. The effects were mediated by participants’ feelings of social presence. The second experiment (N= 40) showed that the observed effects persisted even when participants were shown the purely artificial nature of synthesized speech. These results support the idea that characteristics of synthetic voices in doubly disembodied language settings influence participants’ imagination of virtual speakers, and that technological literacy does not hinder social responses to anthropomorphic technologies such as text‐to‐speech (TTS).     

Hope as a Predictor of Interpersonal Suicide Risk

The current study hypothesized that (1) hope would negatively predict burdensomeness, thwarted belongingness, and acquired capability to enact lethal injury; (2) hope would negatively predict suicidal ideation; and (3) the interpersonal suicide risk factors would predict suicidal ideation. Results indicated that hope negatively predicted burdensomeness and thwarted belongingness, but positively predicted acquired capability to enact suicide. Contrary to our second hypothesis, hope did not predict suicidal ideation, but interpersonal risk factors for suicide predicted suicidal ideation. Results are discussed in terms of implications for hope theory and Joiner's (2005) interpersonal risk factors for suicide, and for clinical practice.     

The Struggle to Prevent and Evaluate: Application of Population Attributable Risk and Preventive Fraction to Suicide Prevention Researach

Population attributable risk (PAR) estimates have been used in suicide research to evaluate the impact of psychosocial and socioeconomic risk factors, including affective disorders, traumatic life events, and unemployment. A parallel concept of preventive fraction (PF), allowing for estimation of the impact of protective factors and effectiveness of preventive interventions, is practically unknown in suicidology. The study authors discuss the application of both concepts to suicide research and prevention, and review literature on the subject. Despite several methodological and conceptual limitations, both PAR and PF are valuable instruments to inform development and evaluation of suicide prevention programs.     

The perception of false self scale for adolescents: Reliability,validity, and longitudinal relationships with depressive and anxious symptoms

A scale assessing generalized false self‐perceptions (Perceptions of False Self, POFS) was developed and tested across three studies involving a total of 331 adolescents (11–16 years). In Study 1, interviews were conducted to develop items for the scale. In Study 2, psychometric techniques were used to derive a scale composed of 16 items. Study 2 also assessed the validity of the scale: depressive symptoms were found to increase POFS across 10 weeks, whereas false self‐perceptions had a reciprocal effect on anxiety. In Study 3, the convergent validity of the POFS scale was established. Overall, the evidence suggests that the POFS scale is a reliable and valid measure of generalized false self‐perceptions.     

Does spreading activation summate?

Summary Network models of semantic memory assume implicitly or explicitly that the degree of activation of a node is a monotonic function of the total amount of excitation reaching that node from all sources. For example, the activation level of the node representing apple should be greater if it is receiving excitation due to the activation of the nodes for fruit and pear than if only one of these neighboring nodes is activated. This notion was tested by presenting semantic primes 80 ms or 320 ms before a letter string (e.g., apple or ipple) requiring a lexical decision. The prime stimuli consisted of a pair of simultaneous items that were identical in the single prime condition (e.g., fruit/fruit or pear/pear) or different in the double prime condition (e.g., fruit/pear or pear/fruit), and were either related (target = apple) or unrelated (target = copper) to the target, or neutral. As predicted by the summation of semantic activation assumption of network models there was a larger priming effect (in the 320 ms SOA condition) following the simultaneous activation of two related nodes than following the activation of only one node.This research was supported by grants to the first author from the Natural Sciences and Engineering Research Council of Canada.