Facts, rules, and procedures in normal calculation: evidence from multiple single-patient studies of impaired arithmetic fact retrieval.

This article presents results from multiple single-case studies of brain-damaged patients with impairments in retrieval of arithmetic facts (i.e., "table" facts such as 8 x 7 = 56). The results provide a basis for exploring the types of knowledge implicated in simple arithmetic performance, the internal representations for the various knowledge types, the processes operating upon these representations, and the ways in which the representations or processes may be disrupted by brain damage.     

Cognitive representations and processes in arithmetic: inferences from the performance of brain-damaged subjects.

In this article, we present data from two brain-damaged patients with calculation impairments in support of claims about the cognitive mechanisms underlying simple arithmetic performance. We first present a model of the functional architecture of the cognitive calculation system based on previous research. We then elaborate this architecture through detailed examination of the patterns of spared and impaired performance of the two patients. From the patients' performance we make the following theoretical claims: that some arithmetic facts are stored in the form of individual fact representations (e.g., 9 x 4 = 36), whereas other facts are stored in the form of a general rule (e.g., 0 x N = 0); that arithmetic fact retrieval is mediated by abstract internal representations that are independent of the form in which problems are presented or responses are given; that arithmetic facts and calculation procedures are functionally independent; and that calculation algorithms may include special-case procedures that function to increase the speed or efficiency of problem solving. We conclude with a discussion of several more general issues relevant to the reported research.     

Effects of COMT genotype on behavioral symptomatology in the 22q11.2 Deletion Syndrome.

The 22q11.2 Deletion Syndrome (DiGeorge/velocardiofacial syndrome) is associated with elevated rates of psychosis, and is also characterized by severe attentional difficulties and executive dysfunction. Behavioral manifestations of this syndrome could result from haploinsufficiency of the catechol-O-methyltransferase (COMT) gene, located within the 22q11 region. The goal of the present study was to examine COMT genotype in relation to behavioral symptomatology in this syndrome. Val158/108Met was genotyped in 38 patients (16 Met/-, 22 Val/-) with confirmed 22q11.2 deletions who had received the Child Behavior Checklist (CBCL) as part of a comprehensive evaluation. Results indicated that the Val genotype was associated with significantly greater internalizing and externalizing behavioral symptomatology in children with 22q11.2 deletions. Val allele status was associated with a greater-than-four-fold increase in risk for clinically significant behavior problems in children with this syndrome. These data are consistent with previous findings of increased psychopathology associated with the Val genotype in normal individuals and suggest that a functional genetic polymorphism in the 22q11 region may influence behavior in individuals with COMT haploinsufficiency.     

Experimentally Increasing Self-Continuity Improves Subjective Well-Being and Protects against Self-Esteem Deterioration from an Ego-Deflating Task

‘Self-continuity,’ or ‘continuous identity’ is the sense of cross-temporal persistence of identity and is associated with positive mood and decreased suicidality. Few studies have examined whether self-continuity is affected by reviewing cross-temporal patterns of personality traits and if increasing self-continuity improves subjective well-being. Study 1 examined the effects of writing about patterns of cross-temporal personality traits and found that this led to increased future self-continuity and reported life satisfaction. Study 2 examined the effects of a structured interview about cross-temporal personality traits and visualizing past/future selves and found that this led to increased future self-continuity, satisfaction with life, positive mood, and less deterioration in self-esteem after an impossible anagram task. These results suggest that increasing self-continuity may improve psychological health and well-being by increasing identity stability.     

The Cognitive Underpinnings of Continuous Identity: Higher Episodic Memory Recall and Lower Heuristic Usage Predicts Highest Levels of Self-Continuity

Continuous identity (CI) is a sense of persistent identity wherein the present self is seen as overlapping with the past and future selves. This study addressed the hypothesis that judgments of CI require successful retrieval of information by examining the relationship between varying levels of CI and two forms of memory recall. The pattern of findings indicated that high levels of cued memory recall combined with low levels of heuristic usage were associated with higher levels of CI, and this occurred for both past-to-present CI and present-to-future CI. We propose that to achieve high levels of CI, individuals need to access and analyze a fund of stored autobiographical information.     

Cross-US reinstatement of human conditioned fear: Return of old fears or emergence of new ones?

Re-exposure to the unconditioned stimulus (US) following fear extinction in the laboratory produces reinstatement of fear. Similarly in clinical situations, anxiety patients may experience adverse events that reinstate fear following successful exposure therapy. The current study employed two USs, shock and loud noise, to examine whether a US that is qualitatively different but of the same valence as the original acquisition US can produce reinstatement in human fear conditioning. Both standard and cross-US reinstatement manipulations led to elevated fear as indexed by skin conductance. However, cross-US reinstatement was accompanied by elevated expectancy of the US that had been presented during the reinstatement manipulation, not the US that had been used to establish fear in acquisition. This result implies that reinstatement may involve the development of new fears. Context conditioning and cognitive processes were implicated as possible mechanisms. The current findings suggest that clinical relapse attributed to reinstatement may not always reflect the reactivation of old fears but may instead represent new fears worthy of clinical examination.     

Lexical factors in the word-superiority effect

In the Reicher-Wheeler paradigm, fluent readers can identify letters better when they appear in a word than when they appear in either a pronounceable pseudoword (a lexicality effect) or a single letter (a word-letter effect). It was predicted that if both of these effects involve a lexical factor, then adult acquired dyslexic subjects whose deficit prevents access to visual word form should show disruptions of the normal effects on the Reicher-Wheeler task. The results were that dyslexic subjects as well as matched control subjects showed a lexicality effect; however, while the control subjects showed a normal word-letter effect, the dyslexic subjects showed a reverse letter-superiority effect. Both effects, however, showed a systematic variation: As performance on lexical decision improved, the subjects' performance on words in the Reicher-Wheeler task was better than that for all the other conditions. These subject correlations were replicated by using data from a second lexical decision experiment, which utilized the same words and pseudowords that were used in the Reicher-Wheeler task. In addition, an item analysis showed that the words that the subjects had discriminated correctly in lexical decision showed a significant advantage over those that they had not, as well as an improvement relative to the other conditions. These results suggest that there is a lexical factor underlying the lexicality and word-letter effects, and it is proposed that the abnormal letter-superiority effect can be accounted for as the manifestation of other competing factors.