Operationalizing the "vulnerability" and "stress" components of the hopelessness theory of depression: a multi-wave longitudinal study

The current study tested of the diathesis-stress component of the hopelessness theory (HT) using (1) a "weakest link" approach towards operationalizing vulnerability (e.g., an individual is as vulnerable to depression as his/her most depressogenic inferential style-DIS) and (2) an idiographic approach towards operationalizing high levels of stress. The procedure involved an initial assessment during which participants completed measures assessing DISs and depressive symptoms. The procedure also involved a series of eight follow-up assessments, occurring every 6 weeks, during which depressive symptoms and hassles were assessed. Hypotheses were tested in two samples of adults (i.e., adults diagnosed with a current MDE and adults diagnosed with a past MDE at Time 1). In line with hypotheses, in both samples, depressogenic weakest links were associated with greater elevations in depressive symptoms following elevations in hassles. At the same time, equally strong support was obtained for the HT when stress was operationalized from a nomothetic perspective and when vulnerability was operationalized as a DIS about causes (but not consequences or self).     

Partial Reinforcement in Appetitive Pavlovian Conditioning with Rats

Four experiments examined the effects of a partial reinforcement schedule on extinction using appetitive Pavlovian conditioning. Extinction was slower after partial than after continuous reinforcement when the schedules were administered to different groups (Experiment 1). The opposite result was found in Experiments 2 and 3 when both schedules were presented to the same group in the same context. When the schedules were presented to the same group in different contexts, then extinction was again slower after partial reinforcement (Experiment 3). Experiment 4 demonstrated that a change of context facilitates extinction to a greater extent after conditioning with a partial reinforcement schedule than with a continuous one. The results are explained by assuming that the nonreinforced trials of a partial reinforcement schedule create an internal state that serves as a contextual cue.     

Effects of a companion dog on associations of danger and threat with oriental-looking targets

In the current study we extend previous findings on the shooter bias toward targets with Arab ethnicity. In an adapted shooter task, we presented stereotypically oriental-looking targets without explicit symbols of Islam (e.g., a turban) and additionally tested if presenting a “harmless” companion dog, together with Arab versus White targets, would affect the shooter bias. Participants responded faster and made fewer errors for armed Arab than for armed White targets. Moreover, compared to the “neutral” no dog condition, the presence of a dog triggered fewer false alarms for White than for Arab targets and slowed down (correct) responses in general. Implications and potential underlying mechanisms are discussed.     

Summation in Autoshaping with Short- and Long-duration Stimuli

Five autoshaping experiments with pigeons examined the effects of presenting in compound two stimuli that had individually been paired with food. The rate of responding during the compound was the same as for the individual stimuli when the stimulus duration was 10 sec. When the duration of the stimuli was 30 sec, the compound elicited a higher response rate than its components. This enhanced rate of responding during the compound was evident only for the initial portion of each trial. Moreover, the enhanced rate of responding was no greater than for a compound composed of an excitatory and a neutral element. These results present difficulties for both elemental and configural theories of conditioning.