Commentary on Steinley and Brusco (2011): recommendations and cautions

I discuss the recommendations and cautions in Steinley and Brusco's (2011) article on the use of finite models to cluster a data set. In their article, much use is made of comparison with the K-means procedure. As noted by researchers for over 30 years, the K-means procedure can be viewed as a special case of finite mixture modeling in which the components are in equal (fixed) proportions and are taken to be normal with a common spherical covariance matrix. In this commentary, I pay particular attention to this link and to the use of normal mixture models with arbitrary component-covariance matrices.     

Cognitive Specificity in Trait Anger in Relation to Depression and Anxiety in a Community Sample

The current research explored 16 of Young's schemas in relation to trait anger and to anxiety and depression symptoms among 262 non‐clinical Australian adults with low‐level symptomatology and average anger levels. The study partially replicated previous work with a sample of Spanish students that investigated the relationship between anger, depression, and anxiety and Young's schemas. Predictions derived from Beck's notion of cognitive specificity were examined using structural equation modelling and showed that of the sixteen schemas, Vulnerability was linked to anxiety, Social Isolation and Enmeshment were linked to depression, and Entitlement, Insufficient Self‐Control, Mistrust and Abuse, Subjugation (negatively), and Abandonment were linked to anger. The discrepancies between these and the Spanish findings and the difficulties of other researchers in establishing higher order aggregations of Young's schemas prompted further consideration of the range of such schemas with respect to anger, depression, and anxiety, and the possibility that sample characteristics may play a critical role in determining the varying affect—schema relationships.     

Biases in Visual Attention in Depressed and Nondepressed Individuals

Abstract

The present study utilised a cognitive paradigm to examine attentional biases in mildly depressed persons. Twelve depressed and 12 nondepressed subjects completed an attentional task similar to that employed by MacLeod, Mathews, and Tata (1986). A tachistiscope was used to present subjects with a series of word pairs, each with one word printed above the other. Three types of word pairs were presented: manic-neutral, depressed-neutral, and manic-depressed. Selective attention to one member of a word pair was assessed using ac perception task. Based on cognitive models of depression, it was hypothesised that the depressed subjects would attend more to depressed-content words than to manic- or neutral-content words, whereas the nondepressed subjects would not exhibit any attentional biases. In contrast to these predictions, analyses indicated that whereas the depressed subjects attended equally to depressed-, manic-, and neutral-content words, the nondepressed subjects attended more to manic-content than they did to neutral- or depressed-content words. These results add support to the documentation of evenhandedness in the cognitive functioning of depressed subjects, and of self-sewing biases in nondepressed subjects. The present findings are discussed in terms of a zoom lens model of attention, in which depressed persons attempt to exhaustively process their sensory world, but with a loss of attentional resolution. In contrast, nondepressed individuals attempt to process a more limited portion of their sensory world, but with an increase in attentional power. Finally, directions for future research in this area are offered.     

Changes in Behaviour and Body Weight Following a Single or Double Social Defeat in Rats

In a series of experiments, the consequences of a single and double social conflict on various behaviours and body weight in rats were studied. Animals were subjected to social defeat by placing them into the territory of an aggressive male conspecific for one hour, either once, or twice at the same time on two consecutive days. To assess the consequences of social defeat, three experiments were performed with independent groups of rats. In the first experiment, an open field test was performed two days after the last conflict. Locomotor activity was strongly reduced after social defeat. There were no differences between the single and double defeat group. To assess the effects of social defeat on subsequent social behaviour, a second experiment was performed in which experimental animals were confronted with an unfamiliar non-aggressive rat two days after a single or double conflict. Social defeat resulted in a reduction of social contact with the unfamiliar conspecific. There was no difference between the single and double conflict group. In the third experiment, the effects of social conflict on food intake, body weight and saccharine preference were measured. Food intake was not affected after a single conflict, but in the double conflict group food intake was decreased for several days. Body weight gain was decreased after both single and double social defeat. The decrease was stronger in the double conflict group. Water intake and saccharine preference were not significantly affected. This study revealed that social defeat in rats causes pronounced changes in various behaviours and body weight. Different aspects of behaviour are differentially affected by defeat with respect to the magnitude and time course of the changes induced. Moreover, different behavioural parameters are differentially sensitive to repetition of the stressor.     

The Impact of Different Forms of #fitspiration Imagery on Body Image,Mood, and Self-Objectification among Young Women

The present study experimentally examined the impact of different forms of inspirational fitness images (“fitspiration”) on women’s body image. Australian female participants (n = 152, 17–30 years-old; M _age = 21.55, SD = 3.94) were randomly assigned to view fitspiration media which depicted the body in a functional (performing exercise) or non-functional (posed) way, with or without accompanying appearance-focused text. There were no main effects of image type or text presence for body satisfaction, mood, or state self-objectification. However, state body satisfaction decreased and negative mood increased over time following exposure to the fitspiration images. Trait self-objectification moderated the impact of image type and text on state body satisfaction, such that viewing functional images presented with appearance-focused text resulted in poorer body satisfaction for women with higher trait self-objectification, but not for those with lower self-objectification. The findings demonstrate that irrespective of focus or presence of text, exposure to fitspiration images decreases body satisfaction and increases negative mood, highlighting the potential negative consequences of engaging with fitspiration media.