How to avoid the fallacies of cognitive subtraction in brain imaging

Functional neuroanatomy of cognitive processes is generally derived by subtraction of a control task from an experimental task. We show that this method is logically untenable and propose to replace it with an adaptation of the specific-effect method and of the additive-factor method. The basic flaw that undermines the subtractive method is the comparison between different tasks. We argue that the specific-effect method should be used when investigating activations produced by different levels of a qualitative variable, whereas the additive-factor method should be used for quantitative variables. The use of these methods allows one to distinguish between parallel and serial stages of processing and between local and distributed processing.     

Rehabilitation of executive deficits in closed head injury and anterior communicating artery aneurysm patients

This paper reports a study that was aimed to rehabilitate executive functions in closed head injury (CHI) and anterior communicating artery (ACoA) aneurysm patients. The groups tested comprised 10 CHI patients, 9 ACoA aneurysm patients and 19 controls. We employed a dual-task paradigm that is known to tap the ability to co-ordinate two actions. The treatment consisted of five experimental sessions, in which the dual-task paradigm was used. In the CHI study, the dual-task cost was measured before the treatment (assessment), immediately after the treatment (retest), and 3 months after the treatment (follow-up). In the ACoA aneurysm study, the dual-task cost was also assessed 12 months after the treatment. A significant reduction of the dual-task cost from assessment to retest was found. This reduction remained stable in the follow-up sessions. The results are discussed with reference to the absence of spontaneous recovery of this specific executive function and to the possibility that the beneficial effect of the treatment generalises to other executive functions and/or daily living activities. Received: 31 March 1999 / Accepted: 23 July 1999     

Disfluencies of 3- and 5-year old Spanish-speaking children

This study examined the disfluent speech of 32 normally fluent monolingual, Spanish-speaking children from Puerto Rico. The total frequencies and types of speech disfluencies were examined in 15 children (8 girls and 7 boys) aged 3;5-4;0 years (M=3.76) and 17 children (8 girls and 9 boys) aged 5;0-5;5 years (M=5.18). When examining the total frequencies of speech disfluencies, results revealed no main effects for age or gender as well as no interactions. Moreover, no differences were observed between the age groups in most of the disfluency types, including the rank orders of the types. Revisions, interjections, and single-syllable word repetitions were the most frequently observed speech disfluencies for both age groups. Broken words, blocks, and repetitions of more than one syllable were the least frequent. Overall, results revealed both similarities and differences when compared with the reported speech behaviors of English-speaking children. EDUCATIONAL OBJECTIVES: The reader will learn about and be able to describe: (1). the influence of age and gender on the total frequencies of speech disfluencies in 3- and 5-year old Spanish-speaking children from Puerto Rico; (2). the amount and type of difluencies in these young children; and (3). how the speech disfluencies of these Spanish-speaking children are similar to and different from those reported in the speech of English-speaking children.     

Hypatia's silence

Hartry Field distinguished two concepts of type‐free truth: scientific truth and disquotational truth. We argue that scientific type‐free truth cannot do justificatory work in the foundations of mathematics. We also present an argument, based on Crispin Wright's theory of cognitive projects and entitlement, that disquotational truth can do justificatory work in the foundations of mathematics. The price to pay for this is that the concept of disquotational truth requires non‐classical logical treatment.     

Number line estimation and complex mental calculation: Is there a shared cognitive process driving the two tasks?

It is widely accepted that different number-related tasks, including solving simple addition and subtraction, may induce attentional shifts on the so-called mental number line, which represents larger numbers on the right and smaller numbers on the left. Recently, it has been shown that different number-related tasks also employ spatial attention shifts along with general cognitive processes. Here we investigated for the first time whether number line estimation and complex mental arithmetic recruit a common mechanism in healthy adults. Participants’ performance in two-digit mental additions and subtractions using visual stimuli was compared with their performance in a mental bisection task using auditory numerical intervals. Results showed significant correlations between participants’ performance in number line bisection and that in two-digit mental arithmetic operations, especially in additions, providing a first proof of a shared cognitive mechanism (or multiple shared cognitive mechanisms) between auditory number bisection and complex mental calculation.     

Exploring the role,needs and challenges of relatives of mothers with HIV or HIV and psychosis: A qualitative study

This study explored types and nature of supports by relatives of mothers living with HIV and psychosis in comparison to mothers with HIV only. Interview data on their experiences of their roles, needs and challenges were collected from 33 relatives on mothers with HIV and psychosis (n=12, females=10, blacks =12, age ranges 21 to 62) and those with HIV only (n=21, females=16, blacks =21, age ranges 18 to 63). The data were thematically analysed utilizing Atlas.ti. The results showed that relatives in both groups provided a variety of supporting roles. Important challenges were experiencing the negative consequences of especially HIV in combination with psychosis in their lives and dealing with the caregiving responsibilities without having enough information. Important strengths included utilizing support networks and remaining hopeful. Support needs for carers of mothers living with HIV related psychosis or HIV only, can be enhanced with increasing social and material resources at the community level. Supporting needs can be addressed by empowering communities through psycho-education.