The attentional blink is not a unitary phenomenon

Identification of the second of two targets is impaired if it is presented less than about 500 ms after the first. Three models of this second-target deficit, known as attentional blink (AB), were compared:resource-depletion, bottleneck, and temporary loss of control (TLC). Five experiments, in which three sequential targets were inserted in a stream of distractors, showed that identification accuracy for the leading target depended on an attentional switch whose magnitude varied with distractor–target similarity. In contrast, accuracy for the trailing target depended on similarity between the target and the trailing mask. These results strongly suggest that the AB is not a unitary phenomenon. Resource-depletion was ruled out as a viable account. The effect of attentional switching was handled naturally by the TLC model, while bottleneck models offered the best account of the effect of backward masking.     

Quantitative measurement of handwriting in the assessment of drug-induced parkinsonism

Monitoring drug-induced side effects is especially important for patients who undergo treatment with antipsychotic medications, as these drugs often produce extrapyramidal side effects (EPS) resulting in movement abnormalities similar to parkinsonism. Scientists have developed several objective laboratory tests to measure and research drug-induced movement disorders, but equipment and tests are complex and costly and have not become accepted in large-scale, multi-site clinical trials. The goals of this study were to test whether a simple handwriting measure can discriminate between individuals with psychotropic-induced parkinsonism, Parkinson's disease, and healthy individuals, and to examine some of the psychometric properties of the measure. We examined pen movement kinematics during cursive writing of a standard word in 13 patients with idiopathic Parkinson's disease (PD), 10 schizophrenia patients with drug-induced parkinsonism (SZ), and 12 normal healthy control participants (NC). Participants were instructed to write the word "hello" in cursive twice, at three vertical height scales. Software was used for data acquisition and analysis of vertical stroke velocities, velocity scaling, and smoothness. There were four important results from this study: (1) both SZ patients with drug-induced EPS and PD participants exhibited impaired movement velocities and velocity scaling; (2) performance on the velocity scaling measure distinguished drug-induced EPS from normal with 90% accuracy; (3) SZ, but not PD participants displayed abnormalities in movement smoothness; and (4) there was a positive correlation between age and magnitude of the velocity scaling deficit in PD participants. This study demonstrates that kinematic analyses of pen movements during handwriting may be useful in detecting and monitoring subtle changes in motor control related to the adverse effects of psychotropic medications.     

Dual-modality monitoring in a classification task: the effects of bilingualism and ageing

Two experiments are reported in which monolingual and bilingual participants who were younger (Experiment 1) or older (Experiment 2) adults performed in a dual-task classification paradigm. Visually (primary task) and auditorily (secondary task) presented stimuli were classified into two categories. The stimuli belonged to two domains, letters or numbers (LN) and animals or musical instruments (AM), and the two task modalities used stimuli from the same (related) or opposite (unrelated) domains. For both age groups, bilinguals were less disrupted than monolinguals in visual sorting in the LN domain, and relatedness affected performance only in the AM domain. The results indicate different processing demands for the two domains, with the simpler domain (LN) favouring bilinguals and the more semantically complex domain (AM) favouring related judgements for the two task modalities.     

Consequential validity of the implicit association test: comment on Blanton and Jaccard (2006)

Numeric values of psychological measures often have an arbitrary character before research has grounded their meanings, thereby providing what S. J. Messick (1995) called consequential validity (part of which H. Blanton and J. Jaccard now identify as metric meaningfulness). Some measures are predisposed by their design to acquire meanings easily, an example being the sensitivity measure of signal detection theory. Others are less well prepared, illustrated by most self-report measures of self-esteem. Counter to Blanton and Jaccard's characterization, the Implicit Association Test (IAT) has properties that predispose it to acquire consequential validity rapidly. With the IAT as the subject of over 250 publications since 1998, there is now much evidence for its consequential validity. The IAT has attracted more scholarly criticism than have other measures designed for similar purposes. The authors speculate as to why the IAT is an attractive target.     

Covariation and quantifier polarity: what determines causal attribution in vignettes?

Tests of causal attribution often use verbal vignettes, with covariation information provided through statements quantified with natural language expressions. The effect of covariation information has typically been taken to show that set size information affects attribution. However, recent research shows that quantifiers provide information about discourse focus as well as covariation information. In the attribution literature, quantifiers are used to depict covariation, but they confound quantity and focus. In four experiments, we show that focus explains all (Experiment 1) or some (Experiment 2-4) of the impact of covariation information on the attributions made, confirming the importance of the confound. Attribution experiments using vignettes that present covariation information with natural language quantifiers may overestimate the impact of set size information, and ignore the impact of quantifier-induced focus.     

The effects of providing access to stimuli following choice making during vocal preference assessments

Two variations of a vocal paired-stimulus preference assessment were evaluated to determine whether the verbal reports of preference, given by individuals with developmental disabilities when no access to the activity was given, matched their verbal reports when access to the activity was given contingent on their choice. The results indicated different outcomes between the two methods for 6 of the 7 participants. Subsequent reinforcer assessments, conducted for 2 participants, showed that activities identified in the preference assessments that provided access contingent on selection resulted in more responding than did activities identified in the preference assessment that did not include access to items following their selection.     

Rapid acquisition in concurrent chains: evidence for a decision model

Pigeons' choice in concurrent chains can adapt to rapidly changing contingencies. Grace, Bragason, and McLean (2003) found that relative initial-link response rate was sensitive to the immediacy ratio in the current session when one of the terminal-link fixed-interval schedules was changed daily according to a pseudorandom binary sequence (e.g., Schofield & Davison, 1997). The present experiment tested whether the degree of variation in delays across sessions had any effect on acquisition rate in Grace et al.'s (2003) rapid-acquisition procedure. In one condition ("minimal variation"), the left terminal link was always fixed-interval 8 s and the right terminal link was either fixed-interval 4 s or fixed-interval 16 s. In the other condition ("maximal variation"), a unique pair of fixed-interval values was used in each session. Responding was sensitive to the current-session immediacy ratio in both conditions, but across subjects there was no systematic difference in sensitivity. These results challenge the view that initial-link responding in the rapid-acquisition procedure is determined by changes in the learned value of the terminal-link stimuli, and suggests instead that a process resembling categorical discrimination may control performance. A decision model based on the assumption that delays are categorized as short or long relative to the history of delays provided a good account of the data and shows promise in being able to explain other choice phenomena.     

Cognitive-behaviour therapy for depersonalisation disorder: an open study

Depersonalisation (DP) and derealisation (DR) are subjective experiences of unreality in, respectively, one's sense of self and the outside world. These experiences occur on a continuum from transient episodes that are frequently reported in healthy individuals to a chronic psychiatric disorder that causes considerable distress (depersonalisation disorder: DPD). Despite the relatively high rates of reporting these symptoms, little research has been conducted into psychological treatments for this disorder. We report on an open study where 21 patients with DPD were treated individually with cognitive behavioural therapy (CBT). The therapy involved helping the patients re-interpret their symptoms in a non-threatening way as well as reducing avoidances, safety behaviours and symptom monitoring. Significant improvements in patient-defined measures of DP/DR severity as well as standardised measures of dissociation, depression, anxiety and general functioning were found at post-treatment and six-months follow-up. Moreover, there were significant reductions in clinician ratings on the Present State Examination (Wing, Cooper & Sartorius, 1974), and 29% of participants no longer met criteria for DPD at the end of therapy. These initial results suggest that a CBT approach to DPD may be effective, but further trials with larger sample sizes and more rigorous research methodology are needed to determine the specificity of this approach.     

The effects of methylphenidate on a functional analysis of disruptive behavior: a replication and extension

In the present investigation, a functional analysis of the disruptive behavior of a 18-year-old man who had been diagnosed with attention deficit hyperactivity disorder and moderate mental retardation was conducted, both when he was taking methylphenidate and when he was not taking the medication. The results of this functional analysis demonstrated that the participant's disruptive behaviors were reinforced by access to attention only when he was not taking methylphenidate.     

Evaluating and developing a multidimensional, dispositional measure of appraisal

Although theories of stress have emphasized the critical role of the appraisal process, the use of dispositional measures of appraisal have not been readily investigated. Using a large multiethnic sample, we examined the factorial validity and dimensionality of a dispositional version of the Stress Appraisal Measure (SAM; Peacock & Wong, 1990). Both exploratory and confirmatory factor analyses resulted in a 4-factor representation of dispositional appraisal fitting better than its originally proposed 6-factor representation. This 4-factor model was invariant across gender groups. Although the 6-factor model purported to measure 3 dimensions of primary appraisal and 3 dimensions of secondary appraisal, these factors were found to be highly unstable and had questionable internal consistency. In contrast, the more parsimonious 4-factor solution identified 4 relative distinct and reliable scales of appraisal: 3 primary (Challenge, Threat, and Centrality) and 1 secondary (Resources). These findings suggest that meaningful dispositional dimensions of appraisal can be derived and incorporated into trait-state models of the stress process.