Alzheimer's disease disrupts arithmetic fact retrieval processes but not arithmetic strategy selection

Three groups of healthy younger adults, healthy older adults, and probable AD patients, performed an addition/number comparison task. They compared 128 couples of additions and numbers (e.g., 4 + 9 15) and had to identify the largest item for each problem by pressing one of two buttons located under each item. Manipulations of problem characteristics (i.e., problem difficulty and splits between correct sums and proposed numbers) enabled us to examine strategy selection and specific arithmetic fact retrieval processes. Results showed that arithmetic facts retrieval processes, which were spared with aging, were impaired in AD patients. However, AD patients were able to switch between strategies across trials according to problem characteristics as well as healthy older adults, and less systematically than healthy younger adults. We discuss implications of these findings for further understanding AD-related differences in arithmetic in particular, and problem solving in general.     

Modality pairing effects and the response selection bottleneck

The present experiment examined the effects of input/output modality pairings on dual-task performance using the psychological refractory period (PRP) procedure. Four groups of participants performed two tasks composed of the same sets of inputs (visual and auditory) and the same sets of outputs (manual and vocal), but with different input/output modality pairings. Whereas modality pairings had only small effects on single-task reaction times, they had large effects on dual-task reaction times. The modality pairing effect cannot stem from differences in the difficulty of stimulus classification or response execution, because these task demands were the same across groups. The effect also does not appear to result from changes in stimulus-response compatibility. The present findings suggest dual-task interference arises not only from postponement of central operations (due to a central bottleneck), but also from a slowing of central operations whose magnitude is sensitive to the input/output modality pairings.     

Sin and bioethics.

The essay starts out with defining the biblical concept of sin in the Old and the New Testaments. The literal knowledge of divine truth is distinguished from its truthful and spiritual interpretation. A further distinction should be made between the Creator of life (God) and the medium or "intermediary creator" (man) of life. I argue for the "single wholeness" of the human race and for the unity of human responsibility in bioethics. In delineating the teaching of the Church on abortion and family planning, I show that the healing of all human diseases, from traditional interventions to genetic ones, is a Christian duty and is in accordance with Christ's mission on earth as long as one has not been directly or indirectly involved in "reproducing" or "designing" one's descendants or destroying or damaging human life even at its very beginnings.     

The effect of test schedules on the formation of linked perceptual classes

After training conditional discriminations among selected stimuli from two perceptual classes, the emergence of novel relations involving other members of both classes was assessed using cross-class probes. The cross-class probes were presented using one of four different testing schedules. In the 2/9 test, nine different probes were presented in each of two test blocks. In the 6/3 test, three different probes were presented in each of six test blocks. In the 18/1-RND test, each of the 18 cross-class probes was presented in separate test blocks. In the 2/9 and 6/3 tests, the cross-class probes were presented in a randomized order within test block. In the 18/1-RND test, the cross-class probes were presented in a randomized sequence. In the 18/1-PRGM test, however, the cross-class probes were presented in a programmed order (i.e., the values of the stimuli in each cross-class probe were changed systematically in the succession of probe presentations). About 55% of the linked perceptual classes emerged during the 2/9, 6/3, and 18/1-RND tests. Thus the number of different probes in a test block did not influence the emergence of classes as long as the probes were presented in a random order. Virtually all classes emerged during the 18/1-PRGM test. Thus at least one ordered introduction of different cross probes resulted in the reliable emergence of linked perceptual classes. Mechanisms responsible for linked perceptual class formation are discussed along with the relation of these classes to other complex categories.     

Hierarchical classes models for three-way three-mode binary data: interrelations and model selection

Several hierarchical classes models can be considered for the modeling of three-way three-mode binary data, including the INDCLAS model (Leenen, Van Mechelen, De Boeck, and Rosenberg, 1999), the Tucker3-HICLAS model (Ceulemans, Van Mechelen, and Leenen, 2003), the Tucker2-HICLAS model (Ceulemans and Van Mechelen, 2004), and the Tucker1-HICLAS model that is introduced in this paper. Two questions then may be raised: (1) how are these models interrelated, and (2) given a specific data set, which of these models should be selected, and in which rank? In the present paper, we deal with these questions by (1) showing that the distinct hierarchical classes models for three-way three-mode binary data can be organized into a partially ordered hierarchy, and (2) by presenting model selection strategies based on extensions of the well-known scree test and on the Akaike information criterion. The latter strategies are evaluated by means of an extensive simulation study and are illustrated with an application to interpersonal emotion data. Finally, the presented hierarchy and model selection strategies are related to corresponding work by Kiers (1991) for principal component models for three-way three-mode real-valued data.     

Clinically useful,research validated assessment of persons with alcohol problems

Advances in treatment approaches available for persons with alcohol problems, particularly the advent of cognitive behavioral and motivational approaches, have made systematic assessment of these problems more important than ever for clinicians. There is a plethora of assessment instruments available, and it is a difficult task for clinicians to conceptualize, select and use these instruments in a coherent fashion. Particularly important in this task is the identification of research validated instruments that provide both clinically useful and psychometrically sound data. This paper presents a model of alcohol assessment and reviews selected research validated instruments that can be assembled into an assessment battery that provides useful data to guide treatment of alcohol problems while also addressing practical concerns encountered by clinicians in practice.     

Effects of sentential context on the processing of unambiguous words by the two cerebral hemispheres

The effect of sentence context on the processing of different aspects of meaning of unambiguous nouns by the two cerebral hemispheres was examined. Participants performed a lexical decision task on target words following two primes, an unambiguous noun preceded by an incomplete sentence. Priming sentences were consistent with either the dominant or the subordinate aspect of meaning of their final unambiguous word. Short and long SOAs were used. A principal finding of this study was that, when compared to unrelated aspects of meaning, for both the short and the long SOAs, the dominant and subordinate aspects of meaning of the unambiguous words were activated regardless of context in both hemispheres. However, the activation of the subordinate aspect of meaning of unambiguous words appears to be more sensitive to sentential context, especially when the unambiguous word is being processed by the left hemisphere.     

Adult age differences in visual word identification: functional neuroanatomy by positron emission tomography

Adult age differences in the neural systems mediating semantic (context-independent) memory were investigated using positron emission tomography (PET). Younger (20-29 years) and older (62-70 years) participants performed lexical decision (word/nonword discrimination) and nonsemantic (simple visual search) baseline tasks during PET scanning. Within the lexical decision task, display duration and presentation rate were varied across scans. The behavioral data suggested that although an age-related slowing was evident in visual feature and response processing, the retrieval of semantic/lexical information was similar for younger and older adults. For both age groups, lexical-related activation occurred in inferior prefrontal and occipitotemporal regions of the left hemisphere. Differential activation, as a function of age group, was observed in the left occipitotemporal pathway as a result of older adults' maintaining higher levels of neural activity in striate cortex (during visual search) and in inferior temporal cortex (during lexical decision). The prefrontal activation was similar for the two age groups. Thus, although this form of semantic memory retrieval does not undergo significant age-related decline, an age-related change in the associated pattern of neural activation is evident. These findings differ from previous neuroimaging studies of episodic (context-dependent) memory retrieval, which have suggested that age-related compensatory mechanisms are expressed primarily by greater activation of prefrontal regions for older adults than for younger adults.     

Linking sight and sound: fMRI evidence of primary auditory cortex activation during visual word recognition

We describe two studies that used repetition priming paradigms to investigate brain activity during the reading of single words. Functional magnetic resonance images were collected during a visual lexical decision task in which nonword stimuli were manipulated with regard to phonological properties and compared to genuine English words. We observed a region in left-hemisphere primary auditory cortex linked to a repetition priming effect. The priming effect activity was observed only for stimuli that sound like known words; moreover, this region was sensitive to strategic task differences. Thus, a brain region involved in the most basic aspects of auditory processing appears to be engaged in reading even when there is no environmental oral or auditory component.     

Essential and Perceptual Attributes of Words in Reflective and On-line Processing

Access to essential and perceptual attributes of word meanings was investigated in a series of tasks. First, perceptual attributes of a number of natural kind concepts were determined by asking participants to generate the most salient features of those concepts; they were asked to assess the importance of both those features and features that fit criteria for essential attributes. Attributes fitting the criteria for essential attributes were found to be judged more important than perceptual attributes in identifying an object and to have more connections to other attributes of the concept. Semantic priming for both types of features was then investigated. Prime-target pairs consisting of the natural kind concept term and the perceptual or essential attribute were presented for lexical decision (Experiments 1a and 1b) or naming (Experiments 2a and 2b). Interstimulus intervals were either 0 or 200 ms. Both types of features were primed at a 200 ms interstimulus interval but only in the lexical decision task.