Apparent causality affects perceived simultaneity

The present research addresses the question of how visual predictive information and implied causality affect audio–visual synchrony perception. Previous research has shown a systematic shift in the likelihood of observers to accept audio-leading stimulus pairs as being apparently simultaneous in variants of audio–visual stimulus pairs that differ in (1) the amount of visual predictive information available and (2) the apparent causal relation between the auditory and visual components. An experiment was designed to separate the predictability and causality explanations, and the results indicated that shifts in subjective simultaneity were explained completely by changes in the implied causal relations in the stimuli and that predictability had no added value. Together with earlier findings, these results further indicate that the observed shifts in subjective simultaneity due to causal relations among auditory and visual events do not reflect a mere change in response strategy, but rather result from early multimodal integration processes in event perception.     

Realism in confidence judgements of performance based on implicit learning

In two experiments we employed calibration methods to investigate the realism of participants' confidence ratings of their own classification performance based on knowledge acquired after training on an artificial grammar. In Experiment 1 participants showed good realism (but overconfidence) for grammatical strings but very poor realism for non-grammatical strings. Method of training (string repetition in writing or mere exposure) did not affect the realism. Furthermore, the participants underestimated their overall performance. In Experiment 2, using a more complex grammar and controlling for two types of associative chunk-strength, participants showed good realism (but still overconfidence) for both letter and symbol strings, irrespective of grammaticality. Together, these experiments show that implicit learning can give rise to knowledge products that are associated with fairly realistic meta-knowledge. It is argued that both the zero-correlation criterion and the guessing criterion are misplaced when used to define implicit knowledge; two reasons being that confidence judgements may be affected both by implicit knowledge and by inferences.     

‘At the level of the word: Nurturing justice in therapeutic conversations’

The issue of social justice and how it unfolds in the lives of persons seeking counselling has been steadily gaining attention in recent times. This development marks a departure from an individualistic perspective that construes problems as functions of personal deficits, thereby overlooking the many social inequities that contribute to the challenges people face. The turn towards social justice manifests primarily in a call for advocacy on behalf of therapy clients. While celebrating these developments, this article suggests that it is not just in interactions outside the consulting room that injustices may be perpetrated. The author invites attention to the ways in which social justice, or the lack thereof, can be understood to unfold within counselling conversations.     

Impact of predatory threat on fear extinction in Lewis rats

Humans with post-traumatic stress disorder (PTSD) are deficient at extinguishing conditioned fear responses. A study of identical twins concluded that this extinction deficit does not predate trauma but develops as a result of trauma. The present study tested whether the Lewis rat model of PTSD reproduces these features of the human syndrome. Lewis rats were subjected to classical auditory fear conditioning before or after exposure to a predatory threat that mimics a type of traumatic stress that leads to PTSD in humans. Exploratory behavior on the elevated plus maze 1 wk after predatory threat exposure was used to distinguish resilient vs. PTSD-like rats. Properties of extinction varied depending on whether fear conditioning and extinction occurred before or after predatory threat. When fear conditioning was carried out after predatory threat, PTSD-like rats showed a marked extinction deficit compared with resilient rats. In contrast, no differences were seen between resilient and PTSD-like rats when fear conditioning and extinction occurred prior to predatory threat. These findings in Lewis rats closely match the results seen in humans with PTSD, thereby suggesting that studies comparing neuronal interactions in resilient vs. at-risk Lewis rats might shed light on the causes and pathophysiology of human PTSD.Following a severe traumatic event, some individuals manifest a syndrome, known as post-traumatic stress disorder (PTSD), characterized by repeated painful recollection of the trauma, avoidance of trauma reminders, intrusive thoughts, startle, hyperarousal, and disturbed sleep. Lifetime prevalence of PTSD ranges from 1.4% to 11.2% in representative samples (Afifi et al. 2010). Review of heritability studies indicate that there is a significant genetic component to PTSD (Nugent et al. 2008) as shared genes explain approximately 25%–38% of variability in PTSD symptom clusters and total symptoms (Afifi et al. 2010). Moreover, PTSD heritability coincides with that of other psychiatric conditions such as generalized anxiety, panic disorder, and depression (Chantarujikapong et al. 2001; Fu et al. 2007), suggesting that these disorders gain expression through common biological pathways.Although our understanding of PTSD has improved recently, we still have a limited grasp of the factors that predispose some to be at risk for PTSD, as well as those contributing to PTSD expression following trauma. In part, this situation results from the ethical limitations associated with human studies. For example, humans cannot be randomly assigned to trauma, and, importantly, the invasive techniques required to study the pathophysiology of PTSD can be used only in animals. Thus, a promising approach toward understanding the underlying pathophysiology of PTSD would be to study the disease in a valid animal model of the human syndrome.Fortunately, much work has already been performed to define an animal model of PTSD that reproduces the salient features of the human syndrome (see Adamec et al. 2006; Cohen et al. 2006a; Siegmund and Wotjak 2006). The most promising research has focused on the impact of exposing rodents to species-relevant threatening stimuli that mimic the kind of life-and-death circumstances that precipitates PTSD in humans. Indeed, rodents exposed to predators or their odor develop long-lasting (3 wk or more) manifestations of anxiety as seen in a variety of behavioral assays including the elevated plus maze (EPM), social interaction test, and acoustic startle (Adamec and Shallow 1993; Blanchard et al. 2003; Adamec et al. 2006). The inherent strength of this species-relevant stimulus was demonstrated in studies where predator odor served as an unconditioned stimulus to support cued or contextual fear conditioning (Blanchard et al. 2001; McGregor et al. 2002). As is the case with human PTSD, differential vulnerability to predatory threat was also observed in rodents. In one study, for instance, the propensity of different strains of rats to develop extreme behavioral manifestations of anxiety (EBMAs) as a result of predatory threat has been characterized, revealing that a much higher proportion (50%) of Lewis rats (an inbred strain) develops EBMAs as a result of an intense predatory threat compared with 10% of Fisher rats and 20% of Sprague–Dawley rats (Cohen et al. 2006b).Although these results are promising, it remains unclear whether Lewis rats also exhibit traits that parallel the pathophysiology of human PTSD. One such factor, thought to play a particularly critical role in the persistence of PTSD, is a compromised ability to extinguish fear memories (for review, see Quirk and Mueller 2008). Two main lines of evidence support this notion. First, in functional imaging studies, the brain structures that normally support fear expression and extinction (for review, see Pape and Pare 2010) show abnormal activity patterns in PTSD (Rauch et al. 2006; Shin et al. 2006; Bremner et al. 2008; Milad et al. 2009). Second, several studies have reported that individuals with PTSD are deficient at extinguishing classically conditioned fear responses (Orr et al. 2000; Peri et al. 2000; Blechert et al. 2007; Milad et al. 2008, 2009). Of particular interest, a study of identical twins discordant for trauma exposure has revealed that this extinction deficit was not a pre-existing condition but developed as a result of trauma (Milad et al. 2008). Given the possibility that an inability to extinguish fear might contribute to the maintenance of PTSD, we therefore tested whether Lewis rats reproduced the properties of extinction seen in human PTSD.     

Stress ulcer and open-field behavior of spontaneously hypertensive,normotensive, and Wistar rats

Spontaneously hypertensive rats (SHRs) and the normotensive Wistar/Kyoto (WKY) rat were observed, along with Wistar rats (which represent the parent strain), on various open-field behaviors. All three strains were subsequently exposed to the activity-stress (A-S) ulcerogenic procedure. SHR and Wistar rats were very active in most open-field measures as compared with WKY rats, but only SHRs were active during the A-S treatment. WKY rats were very ulcer prone and had significantly more ulcers than SHRs, which in turn had more ulcers than Wistar rats. It was anticipated that Wistar rats would resemble the WKY rats, but in most measures the Wistars resembled the SHRs. The study suggests that although WKY rats function as an appropriate control for hypertension studies, these rats may be inappropriate as controls for other physiological and behavioral studies.