Contextual influences in V1 as a basis for pop out and asymmetry in visual search. (33/3957)

I use a model to show how simple, bottom-up, neural mechanisms in primary visual cortex can qualitatively explain the preattentive component of complex psychophysical phenomena of visual search for a target among distracters. Depending on the image features, the speed of search ranges from fast, when a target pops-out or is instantaneously detectable, to very slow, and it can be asymmetric with respect to switches between the target and distracter objects. It has been unclear which neural mechanisms or even cortical areas control the ease of search, and no physiological correlate has been found for search asymmetry. My model suggests that contextual influences in V1 play a significant role.  (+info)

Measuring the amplification of attention. (34/3957)

An ambiguous motion paradigm, in which the direction of apparent motion is determined by salience (i.e., the extent to which an area is perceived as figure versus ground), is used to assay the amplification of color by attention to color. In the red-green colored gratings used in these experiments, without attention instructions, salience depends on the chromaticity difference between colored stripes embedded in the motion sequence and the yellow background. Selective attention to red (or to green) alters the perceived direction of motion and is found to be equivalent to increasing the physical redness (or greenness) by 25-117%, depending on the observer and color. Whereas attention to a color drastically alters the salience of that color, it leaves color appearance unchanged. A computational model, which embodies separate, parallel pathways for object perception and for salience, accounts for 99% of the variance of the experimental data.  (+info)

A problem with auditory processing? (35/3957)

Recent studies have found associations between auditory processing deficits and language disorders such as dyslexia; but whether the former cause the latter, or simply co-occur with them, is still an open question.  (+info)

A critical examination of the application of the Transtheoretical Model's stages of change to dietary behaviours. (36/3957)

This paper proposes that the application of the Transtheoretical Model's stages of change to dietary behaviours may be fundamentally problematic due to the difference in nature between dietary behaviours and the addictive behaviours upon which the model was originally based. It was considered that specific problems associated with stage categorization for dietary change would include: problems due to the potential mismatch between a person's perceived and actual dietary behaviour; and problems due to the use of specific time periods to distinguish between different stages. A total of 541 volunteers completed questionnaires that measured their stage of change with respect to one of three dietary behaviours (healthy eating, eating a low-fat diet, and eating five portions of fruit and vegetables per day). Results indicate that people who were actively making a change (actors) or maintaining a change (maintainers) had done so for a range of different periods of time, with no specific cut-off point being evident. Also, more realistic stage categorizations were evident for the most specific dietary behaviours where there was least likelihood of a mismatch between perceived and actual dietary behaviour. Problems associated with issues of operationalization of the model and the application of the stage model to dietary change are discussed.  (+info)

Pain intensity processing within the human brain: a bilateral, distributed mechanism. (37/3957)

Functional imaging studies of human subjects have identified a diverse assortment of brain areas that are engaged in the processing of pain. Although many of these brain areas are highly interconnected and are engaged in multiple processing roles, each area has been typically considered in isolation. Accordingly, little attention has been given to the global functional organization of brain mechanisms mediating pain processing. In the present investigation, we have combined positron emission tomography with psychophysical assessment of graded painful stimuli to better characterize the multiregional organization of supraspinal pain processing mechanisms and to identify a brain mechanism subserving the processing of pain intensity. Multiple regression analysis revealed statistically reliable relationships between perceived pain intensity and activation of a functionally diverse group of brain regions, including those important in sensation, motor control, affect, and attention. Pain intensity-related activation occurred bilaterally in the cerebellum, putamen, thalamus, insula, anterior cingulate cortex, and secondary somatosensory cortex, contralaterally in the primary somatosensory cortex and supplementary motor area, and ipsilaterally in the ventral premotor area. These results confirm the existence of a highly distributed, bilateral supraspinal mechanism engaged in the processing of pain intensity. The conservation of pain intensity information across multiple, functionally distinct brain areas contrasts sharply with traditional views that sensory-discriminative processing of pain is confined within the somatosensory cortex and can account for the preservation of conscious awareness of pain intensity after extensive cerebral cortical lesions.  (+info)

Family ward: a new therapeutic approach. (38/3957)

This article describes a new integrated child psychiatric family ward treatment model at the Tampere University Hospital. Theoretically, the treatment is based on an integration of systems and psychoanalytical theories as well as behavioral approach. A centerpiece of the model is a 3-week treatment period for the whole family at the family day ward. The work of the multidisciplinary team on the ward focuses on family relationships, on representational level, and on the interactional behavior of the family. Interaction and relationships are also used as tools, including a reflective working model and sharing concrete interaction with the family. So far, the family ward has offered 165 family treatment periods for 113 different families. Altogether in 63% of the total treatment periods one or both parents have had mental illness and in 15% of the total treatment periods there have been serious custody disputes with accusations of sexual abuse of the child. Helping these multi-problem families is a special challenge for our treatment model and at the moment we are developing new methods for assessment and support of parenthood.  (+info)

Modeling patient response to acute myocardial infarction: implications for a tailored technology-based program to reduce patient delay. (39/3957)

We are examining ways in which a clinical information system can favorably influence the appropriateness and rapidity of decision-making in patients suffering from symptoms of acute myocardial infarction. In order to do so, we have developed a theoretically based cognitive model for patient decision making. Our model includes somatic and emotional awareness, perceived threat (vulnerability and susceptibility), expectations of symptoms, self-efficacy and response efficacy to explain the response of an individual their symptoms. Variables are explained within a framework that details how they are interrelated in the context of other moderating variables. With an understanding of the decision process, we are able to collect, maintain and access patient specific data to tailor technology-based interventions unique to the requirements of each individual at various phases of the decision process. Existing clinical information systems at Columbia-Presbyterian Medical Center already address issues related to patient relevant on-line data. Other patient specific information will be collected through on-line questionnaires. By basing our approach on the use of a cognitive model, we can assess the capacity of our interventions to modify variables important to the decision-making process, allowing us to pinpoint which interventions are effective and the reasons why they are ineffective.  (+info)

Dynamics of cognitive aging: distinguishing functional age and disease from chronologic age in a population. (40/3957)

This paper introduces a methodological approach to the dynamics of cognitively normal (i.e., successful) aging compared with aging accompanied by different types of cognitive impairment and dementia. Using secondary analysis of a national representative database (Canadian Study of Health and Aging, 1991-1992), the authors show that the occurrence of an adverse event (symptom, sign, or disease), or the accumulation of a number of events, may be modeled as a logistic function of chronologic age in a population. In the cognitively normal, a linear relation between the logarithm of the odds of events and chronologic age was present for the majority of symptoms and signs. This regression represents the accumulation of each sign in a cognitively successful, aging population. The authors then estimated which ages for this cognitively unimpaired group correspond to the odds of the occurrence of symptoms found for a cognitively impaired population at any given chronologic age. This may be regarded as functional age, based upon the accumulation of a particular functional deficit in the impaired population, analogous to the concept of frailty. The dynamics of aging are a complex process of accumulation of deficits (morbidity), whereby decline from some previously healthy level of synergistically associated symptoms and signs results in distinct patterns of disease and staging. The modeling of these dynamics takes us a step further toward the definition and refinement of disease and normal aging.  (+info)