Allen R. Dobbs

Adult age differences in working memory.

Active and passive measures of short-term memory over a large segment of the adult life span were compared. Two hundred twenty-eight volunteers, aged 30 to 99 years, performed the digit span forward and backward task, the Peterson-Peterson task, and a new working memory task in which active manipulation of information is emphasized. Age differences were slight for passive tasks. For the working memory task, significant declines were found between the ages of 60 to 69 and 70+ years. It is suggested that the age differences may be due to a decrease in the flexibility with which processing changes are made.

A comparative approach to identify unsafe older drivers

The identification of unsafe older drivers is a current and important challenge. In the present research, a comparative approach was used in which the on road driving errors and expert evaluations of older drivers with clinically significant declines in mental abilities (N = 155) were compared to the errors and evaluations of a normal elderly control group (N = 68) and a normal younger control group (N = 30). The results indicate that the conventional criteria used in North America for licensing new drivers is inappropriate for license removal in experienced drivers. The results also indicate that hazardous errors were the single best indicator of membership in the group of older drivers with clinical impairment. This group also differs from the two normal control groups on turn positioning errors, minor positioning errors and overcautiousness. All groups differ from each other on scanning errors. A regression analysis further indicated that the five driving errors listed above accounted for over 57% of the variance associated with global ratings provided by expert driving instructors.

Laypersons' knowledge about the sequelae of minor head injury and whiplash.

Even minor head injuries can result in the post traumatic syndrome, a symptom complex that includes physical discomfort and sleep, sexual, affective, and memory disturbance. Little is known about the laypersons knowledge of the syndrome but this may influence judgements about malingering and attitudes towards victims of minor head injury. Descriptions of rear-end automobile accidents were presented to two groups. One group (n = 22) rated the likelihood of a variety of physical, affective, cognitive, and distractor (never or rarely reported by trauma victims) symptoms. A second group (n = 21) judged the speed necessary to cause each of the symptoms. The results indicated that highly exaggerated speeds were thought necessary to produce even the most common physical symptoms. Moreover, cognitive symptoms were thought to be no more likely than were distractor symptoms. In contrast, the knowledge about physical symptoms, the effects of loss of consciousness and whiplash versus direct head injuries was consistent with what is known from research literature.

Age differences in word finding in discourse and nondiscourse situations

Measures of word finding in discourse (video description task) and nondiscourse situations (word fluency tasks) were obtained from a sample of 90 community-dwelling healthy adults. Age differences were found in the accuracy and uncertainty of the labels used to refer to the characters and objects depicted in the video description task and in the number of correct responses in the category fluency task. There was a significant amount of shared variance between the 2 types of tasks. More important, there was a significant amount of variance in the video discourse task associated with age that was independent of performance in the word fluency task. The communicative impact of a word-finding problem and need for discourse level study are discussed.

Working memory deficits associated with chronic fatigue syndrome.

Cognitive impairments are among the most frequently reported and least investigated components of the chronic fatigue syndrome (CFS). As part of a multifaceted study of the CFS, the present study investigated the cognitive functioning of chronic fatigue patients. The performance of 20 CFS patients was compared to that of controls (N = 20) on 4 tests of working memory (WM). Digit Span Forward was used to assess the storage capacity of WM. Multiple aspects of central executive functioning were assessed using several standard measures: Digit Span Backward, and Trails A and Trails B. More recently developed measures of WM were used to assess control of processing under temporal demands (working memory task) and resistance to interference (a sustained attention task). Deficits were restricted to more demanding tasks, requiring resistance to interference and efficient switching between processing routines. The overall results clearly implicate deficits in the control aspects of central executive function in CFS.

The Impact of Pacemaker Implantation on Cognitive Functioning in Elderly Patients

To describe and quantify the impact of pacemaker implantation on cognitive functioning in the elderly.

Age and sex differences in the mental realignment of maps.

Community-residing young and elderly persons were given six maps with routes indicated by lines connecting dots. The dots were arranged in a 3 x 3 matrix that corresponded to the placement of discs affixed to the testing room floor. Route lengths increased by one segment with each subsequent map. In one condition participants were instructed not to turn the map while walking the indicated route and thus the orientation of the map to the room varied as the person followed the path. In a second condition participants turned the map while following the route, keeping it aligned with the room. Elderly persons made fewer correct choices and took more time to make direction decisions than younger people as did females compared to males. When the map could not be turned, decision times were related to the amount of misalignment between the map and the room. Elderly persons, especially females were influenced more by map misalignment than were young people. The results indicate that mental realignment is an important aspect of route following and may explain some of the difficulty older people have with such tasks.

Attentional demands of visual word recognition

Beckers (1976, 1979, 1980, 1985; Becker & Killion, 1977; Eisenberg & Becker, 1982) verification model was used as a framework to investigate the attentional demands of word recognition. In two experiments, a lexical decision task and an auditory probe task were performed in single- and dual-task conditions. Responses to probes were divided into detection and movement measures that indexed the demands of recognition and response output, respectively. In Experiment 1, single- to dual-task decrements in probe detection performance were larger during low-frequency as compared with high-frequency trials. This finding indicates that the attentional demands of word recognition vary with word frequency. These findings were replicated in Experiment 2, which was designed to separate a response compatibility and a capacity interpretation of the results. The findings are interpreted within Beckers verification model.

Design of Institutions: Cognitive Functioning and Social Interactions of the Aged Resident

Older people experience sensory, cognitive, and social deficits that adversely affect their interaction with the environment. Design of institutions for the elderly resident should be prosthetic to ensure that environments optimally accommodate the functioning of the residents. The sensory and cognitive state of the residents should be considered in everyfacility. This review discusses how sensory and cognitive changes in aging affect orientation and wayfinding as well as how the physical aspects of the environment can accommodate these changes to reduce confusion and disorientation. Environmental features that promote social interaction are reviewed Because the environmental needs and unique characteristics of the cognitively impaired resident differs from that of the nonimpaired resident, special issues in the design of facilities for demented residents are reviewed Conclusions are offered with regard to research needs and applied problems.

Frequency effects in lexical decisions: A test of the verification model.

Lexical decisions about high-frequency words are faster than about low-frequency words. It has been suggested that the locus of this effect is in a verification stage in which a frequency-ordered comparison takes place that requires the continuous availability of a sensory representation of the stimulus. This proposal was tested in a series of four lexical decision studies. In the first, high- and low-frequency words and nonword stimuli remained visible until subjects responded. In the second, the stimuli were illuminated for only one retrace on a video monitor (16.7 ms), and in the third the single retrace was followed by a pattern mask 50 ms later. The latter two conditions have been suggested as manipulations that would eliminate the verification stage of recognition. Nevertheless, the effect of word frequency on decision latencies was comparable in all three studies. Data from a fourth study eliminated orthographic regularity as a factor contributing to the obtained frequency effect. The data suggest that frequency has its effects prior to verification and that the notion of verification as the sole basis for frequency effects needs to be revised.