Attention mechanisms

An improved understanding of the neurobiological substrates underlying attentional mechanisms, as well as the mechanisms of stimulant action, could aid in the development of future medication formulations. The lack of data on stimulant use in particular populations, especially among preschoolers and children with developmental disabilities, and questions regarding the safety and efficacy of long-term stimulant treatment underscore the need for further research. 

The pharmacological management of motor hyperactivity and impaired attentional mechanisms in individuals with PDDs has proven particularly challenging for clinicians and researchers. These symptoms are most prominent in younger autistic children. Thus, these symptoms are largely present during a time when educational programming and interventions are most critical. 

The effects of muscarinic cholinergic agents on memory function have been extensively investigated, and blockade with such agents has been proposed as a possible model for the cognitive failure seen in AD (Sunderland et al. 1988). However, many of the results of such studies can be interpreted as effects on attentional mechanisms or decision processes rather than true memory effects (i.e., effects on encoding, storage, or retrieval) (Beatty et al. 1986). 

Prepulse Inhibition. Abnormalities in information processing and attention mechanisms have long been recognized as hallmark characteristics of schizophrenia. Prepulse in-... 

Current studies of male courtship pheromones focus on the contribution of these pheromones to individual male mating success. This emphasis on individual reproductive success is a distinct shift from earlier assumptions that courtship pheromones served primarily for species identification (e.g., Butler, 1970, p. 43). This earlier emphasis prevailed at a time when the species concept was receiving much attention mechanisms that prevented interspecific matings were of special interest. Courtship pheromones, however, only function after potential conspecific mates have located one another. Courtship pheromones affect a female s receptivity towards a particular conspecific male, and consequently affect the mating success of that male relative to the success of other conspecifics. 

The main visual attention mechanism is the direction of gaze which ensures that the stimulus from the object being looked at is directed to the most sensitive part of the retina (fovea) where it can be analysed in detail. The rest of the field of view is relegated to the less sensitive parts of the retina. In normal activity this centre of focus is shifted constantly in a search pattern which ranges over the field of view until an object of interest is picked out. The visual sense can be tuned to seek out a particular facet such as a defect in a machine or component, provided that we know in advance what characteristics to tune it to. This ability is known as perceptual set. ... 

These selective attention mechanisms are extremely efficient and invaluable in many tasks. But any mechanism which is selective carries with it the penalty that information which does not conform to the characteristics selected by the filter will not get through to the brain, however important that information is. People can be concentrating so hard on one task that they are unaware of other information. Hence someone can fall down a hole because they were staring at some activity going on in the opposite direction. Presetting the filter can also lead to false alarms searching a list for the name Jones we can sometimes be fooled by James. The cost of a rapid response is an increase in errors. 

Process of recognition of danger and its consequences attention mechanisms. Effectiveness of verbal, written and pictorial warnings. 

This reaction, as well as other biochemical reactions in which PO can be an intermediate, is gaining increased attention. Mechanisms involving bioorganic phosphate esters are extremely important in elucidating the reactions of... 

Sensory defects Protective clothing Attention mechanisms... 

Visibility and expectancy. Expectancy, in the context of pedestrian detection, is a psychological variable that represents the degree to which the driver anticipates a pedestrian on the road. To be detected an unexpected object must be conspicuous to attract the drivers fixation (and attention). In contrast, detecting an expected object involves a visual search that is directed at detecting the object s most salient features. If we also know where the object is likely to appear, the process is much quicker because our visual fixation and attentional mechanisms are already directed at it (see Chapters 3 and 4 for a discussion on the difference between top-down and bottom-up processing and visual attention, respectively). Several studies have demonstrated the importance of expectancy for pedestrian detection. The effect was first quantified nearly three quarters of a century ago by Roper and Howard (1938), who measured driver s detection distance to an obstacle on the road when it was either expected or unexpected. With 46 drivers/observers they found that "the average driver perceives the unexpected obstacle only half as far away as from the expected one...all of them saw the unexpected obstacle at least 20 percent as far as the expected obstacle, whereas none saw it at more than 80 percent of the distance." (pp. 419-420). Thus, this seminal study showed that an imexpected pedestrian is likely to be detected at half the distance as an expected one. 

---