The relation between hierarchical and euclidean models for psychological distances

In one well-known model for psychological distances, objects such as stimuli are placed in a hierarchy of clusters like a phylogenetic tree; in another common model, objects are represented as points in a multidimensional Euclidean space. These models are shown theoretically to be mutually exclusive and exhaustive in the following sense. The distances among a set ofn objects will be strictly monotonically related either to the distances in a hierarchical clustering system, or else to the distances in a Euclidean space of less thann — 1 dimensions, but not to both. Consequently, a lower bound on the number of Euclidean dimensions necessary to represent a set of objects is one less than the size of the largest subset of objects whose distances satisfy the ultrametric inequality, which characterizes the hierarchical model.This work was supported in part by Grant GB-13588X from the National Science Foundation. I would like to thank L. M. Kelly and A. A. J. Marley for their helpful comments and suggestions.     

Assaultive violence and the risk of posttraumatic stress disorder following a subsequent trauma

Breslau, Peterson, and Shultz (2008) reported that prior trauma alone, in the absence of PTSD, did not predict an increased PTSD risk, relative to no prior trauma. Only prior trauma that resulted in PTSD predicted an increased PTSD risk following a subsequent trauma. Recently, Cougle, Resnick, and Kilpatrick (2009) proposed that the effect of prior trauma might vary by type of prior trauma, a possibility not considered in Breslau et al. They report that childhood sexual or physical assault, in the absence of PTSD, increased the PTSD risk following a subsequent trauma. This report examines the PTSD effects of prior assaultive violence, using data from Breslau et al. (1998). The study assessed PTSD in relation to up to three events. Analysis was performed on the subset with PTSD assessment for two distinct events, the earliest trauma and a subsequent trauma (n = 967), using as reference persons with no prior trauma (n = 972). Neither prior assaultive violence nor other prior traumas, in the absence of PTSD, influenced the subsequent risk of PTSD. In contrast, prior PTSD increased considerably the PTSD risk of a subsequent trauma. The limitations in Cougle et al. (2009) and in this study and future research directions are discussed.     

Positive mood effects on delay discounting

Delay discounting is the process by which the value of an expected reward decreases as the delay to obtaining that reward increases. Individuals with higher discounting rates tend to prefer smaller immediate rewards over larger delayed rewards. Previous research has indicated that personality can influence an individual's discounting rates, with higher levels of Extraversion predicting a preference for immediate gratification. The current study examined how this relationship would be influenced by situational mood inductions. While main effects were observed for both Extraversion and cognitive ability in the prediction of discounting rates, a significant interaction was also observed between Extraversion and positive affect. Extraverted individuals were more likely to prefer an immediate reward when first put in a positive mood. Extraverts thus appear particularly sensitive to impulsive, incentive-reward-driven behavior by temperament and by situational factors heightening positive affect.     

Cat-Calls and Culpability: Investigating the Frequency and Functions of Stranger Harassment

Stranger harassment is defined as experiencing unwanted sexual attention from strangers in public contexts. We conducted two studies investigating the person and situation factors of U.S. undergraduate males that facilitate stranger harassment. Men from a large Midwestern university indicated their engagement in harassment both when alone and in groups, as well as their motives for this behavior in both settings. We also assessed their Likelihood to Sexually Harass (LSH). We predicted that high LSH men would be most likely to report engaging in harassment when in groups, compared to when alone. We also predicted these group behaviors would be motivated by anonymity and group bonding. Results support our hypotheses about the predictors and motives of stranger harassment in college men.     

Even frequent and expected words are not identified without spatial attention

Previous studies have disagreed about the extent to which people extract meaning from words presented outside the focus of spatial attention. The present study examined a possible explanation for such discrepancies inspired by attenuation theory: Unattended words can be read more automatically when they are expected within a given context (e.g., due to frequent repetition). We presented a brief prime word in lowercase, followed by a target word in uppercase. Participants indicated whether the target word belonged to a particular category (e.g., “sports”). When we used a visual cue to draw attention to the location of the prime word, it produced substantial priming effects on target responses (i.e., especially fast responses when the prime and target words were identical or from the same category). When prime words were not attended, however, they produced no priming effects. This finding replicated even when there were only four words, each repeated 160 times during the experiment. It appears that very little word processing is possible without spatial attention, even for words that are expected and frequently presented.     

Knowing That P without Believing That P

Most epistemologists hold that knowledge entails belief. However, proponents of this claim rarely offer a positive argument in support of it. Rather, they tend to treat the view as obvious and assert that there are no convincing counterexamples. We find this strategy to be problematic. We do not find the standard view obvious, and moreover, we think there are cases in which it is intuitively plausible that a subject knows some proposition P without—or at least without determinately—believing that P. Accordingly, we present five plausible examples of knowledge without (determinate) belief, and we present empirical evidence suggesting that our intuitions about these scenarios are not atypical.     

Working Memory Demands and Semantic Sensitivity for Prose in Mild Alzheimer's Disease

The debate continues with regard to whether degradation of semantic knowledge or deficits in information processing lead to impaired memory performance in patients with Alzheimer's disease (AD). This study examined the effects of semantic content and working memory demands on the recall and recognition abilities of patients with mild AD. Nineteen patients with probable AD and 19 demographically matched normal control participants were asked to remember prose passages that varied in semantic content (high, medium, and low level of idea importance) and working memory demands (narrative and expository passages). Compared to the controls, patients with mild AD lost the ability to recall prose in a manner consistent with the semantic structure of the passages as the demands on working memory increased. Furthermore, as the demands on working memory increased, patients recognized information in a manner that suggested their initial processing was of isolated details rather than by semantic structure. This study provides support for the hypothesis that information processing deficits contribute to impaired semantic processing in patients with mild AD.     

Hobbes and the Imitation of God

This note discusses the implications of an incorrect quotation that appeared in Ted H. Miller's article, 'Thomas Hobbes and the Constraints that Enable the Imitation of God', from Inquiry42.2 (1999). Although surely inadvertent, this error is significant because the author uses it to support the thesis that Hobbes envisions philosophers imitating God by creating order out of chaos. The correct quotation from Leviathandoes not support such a thesis, and the paragraph in Leviathanfrom which it is taken actually runs counter to it. The correct quotation, taken in its context, and a passage from De Corporecited by Professor Miller reveal that Hobbes encourages philosophers to imitate God by following the order of creation in contemplation. In other words, philosophers imitate God by imitating the creation.     

Repetition and Lag Effects in Movement Recognition

Whether repetition and lag improve the recognition of movement patterns was investigated. Recognition memory was tested for one repetition, two-repetitions massed, and two-repetitions distributed with movement patterns repeated at lags of 3, 5, 7, and 13. Recognition performance was examined both immediately afterwards and following a 48 hour delay. Both repetition and lag effects failed to be demonstrated, providing some support for the claim that memory is unaffected by repetition at a constant level of processing (Craik & Lockhart, 1972). There was, as expected, a significant decrease in recognition memory following the retention interval, but this appeared unrelated to repetition or lag.     

Rapid facial reactions to emotional facial expressions in typically developing children and children with autism spectrum disorder

Typical adults mimic facial expressions within 1000 ms, but adults with autism spectrum disorder (ASD) do not. These rapid facial reactions (RFRs) are associated with the development of social-emotional abilities. Such interpersonal matching may be caused by motor mirroring or emotional responses. Using facial electromyography (EMG), this study evaluated mechanisms underlying RFRs during childhood and examined possible impairment in children with ASD. Experiment 1 found RFRs to happy and angry faces (not fear faces) in 15 typically developing children from 7 to 12 years of age. RFRs of fear (not anger) in response to angry faces indicated an emotional mechanism. In 11 children (8-13 years of age) with ASD, Experiment 2 found undifferentiated RFRs to fear expressions and no consistent RFRs to happy or angry faces. However, as children with ASD aged, matching RFRs to happy faces increased significantly, suggesting the development of processes underlying matching RFRs during this period in ASD.