A Computational Evaluation of Sentence Processing Deficits in Aphasia

Individuals with agrammatic Broca's aphasia experience difficulty when processing reversible non‐canonical sentences. Different accounts have been proposed to explain this phenomenon. The Trace Deletion account (Grodzinsky, 1995, 2000, 2006) attributes this deficit to an impairment in syntactic representations, whereas others (e.g., Caplan, Waters, Dede, Michaud, & Reddy, 2007; Haarmann, Just, & Carpenter, 1997) propose that the underlying structural representations are unimpaired, but sentence comprehension is affected by processing deficits, such as slow lexical activation, reduction in memory resources, slowed processing and/or intermittent deficiency, among others. We test the claims of two processing accounts, slowed processing and intermittent deficiency, and two versions of the Trace Deletion Hypothesis (TDH), in a computational framework for sentence processing (Lewis & Vasishth, 2005) implemented in ACT‐R (Anderson, Byrne, Douglass, Lebiere, & Qin, 2004). The assumption of slowed processing is operationalized as slow procedural memory, so that each processing action is performed slower than normal, and intermittent deficiency as extra noise in the procedural memory, so that the parsing steps are more noisy than normal. We operationalize the TDH as an absence of trace information in the parse tree. To test the predictions of the models implementing these theories, we use the data from a German sentence—picture matching study reported in Hanne, Sekerina, Vasishth, Burchert, and De Bleser (2011). The data consist of offline (sentence‐picture matching accuracies and response times) and online (eye fixation proportions) measures. From among the models considered, the model assuming that both slowed processing and intermittent deficiency are present emerges as the best model of sentence processing difficulty in aphasia. The modeling of individual differences suggests that, if we assume that patients have both slowed processing and intermittent deficiency, they have them in differing degrees.     

Perceptual saliency of points along the contour of everyday objects: a large-scale study

The aim of this large-scale study was to find out which points along the contour of a shape are most salient and why. Many subjects (N=161) were asked to mark salient points on contour stimuli, derived from a large set of line drawings of everyday objects (N=260). The database of more than 200,000 marked points was analyzed extensively to test the hypothesis, first formulated by Attneave (1954), that curvature extrema are most salient. This hypothesis was confirmed by the data: Highly salient points are usually very close to strong curvature extrema (positive maxima and negative minima). However, perceptual saliency of points along the contour is determined by more factors than just local absolute curvature. This was confirmed by an extensive correlational analysis of perceptual saliency in relation to ten different stimulus factors. A point is more salient when the two line segments connecting it with its two neighboring salient points make a sharp turning angle and when the 2-D part defined by the triplet of salient points is less compact and sticks out more.     

Smarter than we think: when our brains detect that we are biased

Human reasoning is often biased by stereotypical intuitions. The nature of such bias is not clear. Some authors claim that people are mere heuristic thinkers and are not aware that cued stereotypes might be inappropriate. Other authors claim that people always detect the conflict between their stereotypical thinking and normative reasoning, but simply fail to inhibit stereotypical thinking. Hence, it is unclear whether heuristic bias should be attributed to a lack of conflict detection or a failure of inhibition. We introduce a neuroscientific approach that bears on this issue. Participants answered a classic decision-making problem (the "lawyer-engineer" problem) while the activation of brain regions believed to be involved in conflict detection (anterior cingulate) and response inhibition (lateral prefrontal cortex) was monitored. Results showed that although the inhibition area was specifically activated when stereotypical responses were avoided, the conflict-detection area was activated even when people reasoned stereotypically. The findings suggest that people detect their bias when they give intuitive responses.     

To whom does voice in groups matter? Effects of voice on affect and procedural fairness judgments as a function of social dominance orientation

The authors investigated the effects of voice--the opportunity to provide input in decision-making processes--on perceptions of procedural fairness. In particular, the authors studied the moderating role of social dominance orientation (SDO) in shaping this relation. SDO is an important individual differences variable that causes people to favor unequal relationships within and between social groups. Results revealed that voice was more strongly related to fairness judgments when participants had a high rather than low SDO. Moreover, positive affect mediated this moderation effect. The authors interpreted these results to indicate that high-SDO participants were especially sensitive to voice manipulations because such manipulations enhance perceptions of control over group resources and outcomes. The authors conclude by discussing alternative explanations based on other fairness theories.     

Invariance and convergent and discriminant validity between mothers' and fathers' ratings of oppositional defiant disorder toward adults, ADHD-HI, ADHD-IN, and academic competence factors within Brazilian, Thai, and American children

Confirmatory factor analysis was used to test the invariance of an oppositional defiant disorder toward adults, attention-deficit/hyperactivity disorder-hyperactivity/impulsivity, attention-deficit/hyperactivity disorder-inattention, and an Academic Competence factor model between mothers' and fathers' ratings within Brazilian (n = 894), Thai (n = 2,075), and American (n = 817) children with the Child and Adolescent Disruptive Behavior Inventory (G. L. Burns, T. Taylor, & J. Rusby, 2001a, 2001b). The results showed invariance of item loadings, intercepts, and residuals, as well as factor variances, covariances, and means between mothers' and fathers' ratings within each sample. Convergent and discriminant validity was also observed for the between-parent factor correlations, thus providing additional support for the construct validity of the Child and Adolescent Disruptive Behavior Inventory. The confirmatory factor analysis invariance procedure provides a much better way to examine between-source ratings of behavior problems in children than do the simple correlation and raw discrepancy score procedures.