RESUMEN
The present research examined people's responses towards others' exclusion experience. The authors predicted that both causal attributions and empathy would mediate whether people affiliate with a victim of an ambiguous exclusion experience. Perceivers observing another's exclusion (relative to inclusion) without clearly announced reasons chose to affiliate with the target and this was mediated by increased external attributions for the exclusion (Studies 1a, 1b, 2). When the attributions people made for the exclusion of a target was experimentally manipulated, internal attributions decreased desire for affiliation relative to external or ambiguous attributions, and this was mediated by differences in empathy for the target (Study 3). Further, external attributions arisen from perceiving a causally unclear exclusion leads to an empathetic response which results in an increased desire to affiliate with the target (Study 4). Future directions on perceptions of those who have been excluded are discussed.
Asunto(s)
Empatía , Conducta Social , Aislamiento Social , Adulto , Femenino , Humanos , Control Interno-Externo , Masculino , Modelos Psicológicos , Psicología Social , Percepción Social , Encuestas y Cuestionarios , Adulto JovenRESUMEN
Songbirds exhibit seasonal plasticity in a broad variety of behavioral and morphological traits associated with reproduction. Changes in song production are well described while changes in song reception are not. In the present study, we test for seasonal variation in auditory processing of the house sparrow (Passer domesticus L.) using auditory brainstem responses (ABRs) to tone bursts. We measured amplitude and latency of the first ABR peak in spring, summer and autumn at stimulus frequencies from 0.8 to 6.4 kHz and intensity levels from 24 to 80 dB SPL. ABR thresholds were determined at each frequency using cross-correlation. Amplitude was greater in spring than in autumn at frequencies from 3.2 to 6.4 kHz whereas latency and thresholds exhibited no seasonal variation. The results indicate an increase in the number or temporal synchrony of responses from peripheral auditory neurons during the early breeding season. Changes in peripheral auditory processing may enhance temporal coding of the fine structure and envelope of song; thereby, improving assessment of encoded information in both sexes (e.g. individual identity and dominance status) and auditory feedback during song production in males. Peripheral auditory changes may be mediated by reproductive hormones, and could involve changes in hair cell density on the basilar papilla. Our results suggest that peripheral auditory processing of songbirds changes seasonally in parallel with other behavioral and morphological traits, such as song production.
Asunto(s)
Percepción Auditiva/fisiología , Estaciones del Año , Gorriones/fisiología , Estimulación Acústica , Animales , Potenciales Evocados Auditivos del Tronco Encefálico/fisiología , Femenino , Indiana , Masculino , Modelos Estadísticos , Reproducción/fisiologíaRESUMEN
Polydimethylsiloxane (PDMS) is widely used in a number of industrial processes and consumer products that result in down-the-drain disposal. The log p value for the PDMS used in the present study was 10, and the vapor pressure and water solubility values were below detection limits. These physicochemical characteristics and a measured degradation rate of 3% after six months in moist soils suggest that PDMS may accumulate in aquatic sediments. Sediment toxicity tests with the amphipod Hyalella azteca and with larvae of the midge Chironomus tentans were used to assess the potential for toxicity of PDMS-amended sediments to benthic invertebrates in short-term (10-d) and whole-life-cycle (28 d for H. azteca, 50-65 d for C. tentans) exposures. Endpoints for short-term tests included survival and growth, while life-cycle assays considered survival, growth, reproduction, and, for C. tentans only, emergence. Short-term and life-cycle exposures to concentrations of > or = 1,000 mg PDMS/kg sediment (dry wt) indicated that PDMS will not reduce survival, growth, or reproduction in H. azteca or C. tentans.
Asunto(s)
Chironomidae , Materiales Biocompatibles Revestidos/toxicidad , Crustáceos , Dimetilpolisiloxanos/toxicidad , Sedimentos Geológicos/química , Siliconas/toxicidad , Animales , Larva/crecimiento & desarrollo , Reproducción/efectos de los fármacos , Solubilidad , Análisis de Supervivencia , VolatilizaciónRESUMEN
Concentrations of PCBs, DDTs, toxaphene, chlordanes, dieldrin, and mercury were determined in smallmouth bass (Micropterus dolomieui) collected from Fumee Lake, a remote lake in the Upper Peninsula of Michigan. An ecological hazard assessment was conducted to determine potential impacts of contaminants on bald eagles and mink eating fish from this lake. Concentrations of organochlorines, except toxaphene, and mercury in smallmouth bass were similar to those found in fish from Lake Superior, where atmospheric inputs are the primary sources. Bioaccumulation was indicated by a positive correlation between fish weight and contaminant concentrations for organochlorines, while mercury concentrations did not appear to correspond predictably to body weight. Concentrations of mercury and PCBs in smallmouth bass were sufficiently great to be of concern regarding their consumption by eagles or mink.