Semantic priming after severe closed head trauma: Automatic and attentional processes.

The 2-process theory of semantic priming (J. H. Neely, 1977; M. I. Posner and C. R. Snyder, 1975) was used to determine the maintenance of automatic processes after severe closed head injury (CHI) and to determine whether processes that demand attention suffer a deficit. Ss with severe CHI (N?=?18,?>?2 yrs postinjury) and 18 matched control Ss completed a lexical decision task in which a category prime was followed by a target. Automatic and attentional priming were determined by orthogonally varying prime–target relatedness, expectancy, and stimulus onset asynchrony. Although the CHI Ss had slower reaction times (RTs) overall, there were no significant group differences in the magnitude of either the automatic or attentional component of semantic priming. The present results indicate the integrity of semantic processes and normal semantic priming in long-term patients with severe CHI. The results are discussed in relation to an attentional resource hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characterizing multiple memory deficits and their relation to everyday functioning in individuals with mild cognitive impairment.

The authors evaluated multiple memory processes and explored their contributions to everyday functional limitations in persons with mild cognitive impairment (MCI). Participants included individuals with amnestic MCI, nonamnestic MCI, and healthy older adults. As expected, the amnestic MCI group performed more poorly than the control and nonamnestic MCI groups on a content memory measure. Both MCI groups, however, performed more poorly than controls on the noncontent memory measures of prospective memory, temporal order memory, and source memory. Informants also reported that the MCI groups were experiencing greater difficulty than controls completing instrumental activities of daily living (IADLs). Noncontent memory measures were found to make an independent contribution to IADL performances over and above that of content memory. These findings demonstrate that impairments in memory beyond the traditionally assessed content memory are present in individuals with amnestic MCI and with nonamnestic MCI. The results further show that these noncontent memory processes, which have been linked with executive functioning, play a role in supporting IADLs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Costs of a predictable switch between simple cognitive tasks following severe closed-head injury.

The authors used a predictable, externally cued task-switching paradigm to investigate executive control in a severe closed-head injury (CHI) population. Eighteen individuals with severe CHI and 18 controls switched between classifying whether a digit was odd or even and whether a letter was a consonant or vowel on every 4th trial. The target stimuli appeared in a circle divided into 8 equivalent parts. Presentation of the stimuli rotated clockwise. Participants performed the switching task at both a short (200 ms) and a long (1,000 ms) preparatory interval. Although the participants with CHI exhibited slower response times and greater switch costs, similar to controls, additional preparatory time reduced the switch costs, and the switch costs were limited to the 1st trial in the run. These findings indicate that participants with severe CHI were able to take advantage of time to prepare for the task switch, and the executive control processes involved in the switch costs were completed before the 1st trial of the run ended. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual selective attention after severe closed head injury

This study investigated the nature of selective attention deficits after severe closed head injury (CHI). Twenty participants with severe CHI (greater than 1 year postinjury) and 20 matched controls completed search and nonsearch visual selective attention tasks under conditions of low (Experiment 1) and high (Experiment 2) target-distractor similarity. In the search situations, participants searched visual displays that contained 1, 4, or 8 items for the targets. In the nonsearch situations, the location of the targets was visually cued with a peripheral arrow. The results revealed that in both the low and high target-distractor similarity search conditions. CHI participants required a longer time than controls to locate and identify the target. In contrast, in the nonsearch condition, CHI participants were able to successfully ignore irrelevant task information when target-distractor similarity was low. However, when target-distractor similarity was high, CHI participants had more difficulty than controls ignoring the irrelevant information. These results suggest that, in comparison to controls, CHI participants may be at a disadvantage in selective attention situations when visual search is required and when the discriminability between targets and distractors is difficult.     

Intactness of inhibitory attentional mechanisms following severe closed-head injury.

Attentional problems are a common sequelae of closed-head injury (CHI). Research in the area of selective attention has pointed to the role of inhibitory mechanisms in the suppression of irrelevant information. In the current study, a negative priming paradigm was used to assess the inhibitory mechanisms of individuals suffering from a severe CHI. Twenty participants with severe CHIs (greater than 1 year postinjury) and 20 matched controls completed a negative priming task, as well as several other standardized tests of cognitive functioning. Within the negative priming task, 2 conditions were used to elicit information regarding facilitation by attended and ignored information and 1 condition was used to elicit inhibition of ignored information, as compared with a neutral control condition. Despite poorer performances on several tests of attention, there were no significant differences in the amount of inhibition displayed by the CHI participants as compared with the controls. Findings suggest that inhibitory processing deficits may not underlie the selective attention difficulties commonly seen following a severe CHI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

PUCK: an automated prompting system for smart environments: toward achieving automated prompting—challenges involved

The growth in popularity of smart environments has been quite steep in the last decade and so has the demand for smart health assistance systems. A smart home-based prompting system can enhance these technologies to deliver in-home interventions to users for timely reminders or brief instructions describing the way a task should be carried out for successful completion. This technology is in high demand given the desire of people who have physical or cognitive limitations to live independently in their homes. In this paper, with the introduction of the “PUCK” prompting system, we take an approach to automate prompting-based interventions without any predefined rule sets or user feedback. Unlike other approaches, we use simple off-the-shelf sensors and learn the timing for prompts based on real data that are collected with volunteer participants in our smart home test bed. The data mining approaches taken to solve this problem come with the challenge of an imbalanced class distribution that occurs naturally in the data. We propose a variant of an existing sampling technique, SMOTE, to deal with the class imbalance problem. To validate the approach, a comparative analysis with cost-sensitive learning is performed.     

Effects of divided attention and time course on automatic and controlled components of memory in older adults.

The relation between attention available at encoding and automatic and consciously controlled aspects of memory was investigated within a single task using the process-dissociation procedure (L. L. Jacoby, 1991). Sixty-four older adults and 64 young adults studied a word list in either a full or a divided attention condition. Recall cued with word stems was tested immediately and at 20-minute and 60-minute delays. In contrast to consciously controlled influences of memory, automatic influences of memory (a) showed generally no reliable age differences, (b) remained invariant across the manipulation of attention, and (c) remained relatively invariant across the 60-minute time course. Furthermore, age did not interact with the attentional manipulation or the time course factor. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of divided attention on implicit and explicit memory performance following severe closed head injury.

This study investigated the relation between attentional limitations and memory impairments in patients with closed head injuries (CHI). Twenty-seven CHI participants ( > 1 year postinjury) and 27 matched controls rated their liking of target words under conditions of full and divided attention. Participants then completed an implicit test of tachistoscopic identification (TI) and an explicit test of recognition for the target words As expected, the results revealed impaired explicit memory but preserved perceptually driven implicit memory performance following a CHI. Contrary to what was hypothesized, a reduction in attention available at encoding did not disproportionately impair the recognition performance of the CHI patients. Finally, unlike controls, the CHI participants' priming scores on the TI task were significantly affected by dividing attention at encoding. However, this finding interacted with CHI participants perceptual processing rates, suggesting that nonmemory cognitive factors may influence measured performances on implicit memory tests. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Automatic process development following severe closed head injury.

Automatic process development was investigated in a closed head injury (CHI) population. Ten severe CHI participants (>1 year postinjury) and 10 matched controls completed consistent mapping (CM) and varied mapping (VM) semantic-category memory search tasks. In VM search, despite a similar pattern of serial memory search, the CHI participants responded slower than controls and exhibited slower memory search rates throughout practice (1,800 trials). In CM search, after extensive practice (1,800 trials) both groups showed the performance characteristics indicative of automatic process development, that is, near-zero slopes and large reductions in response times. However, the CHI participants were slower to automatize the task. These results indicate that for memory-based search tasks the effects of a CHI may slow down the speed with which automatic processes develop but that CHI participants can acquire and use automatic processes in task performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Feeling of knowing in episodic memory following moderate to severe closed-head injury.

The ability to accurately monitor one's memory is a metacognitive process that is important in everyday life. The authors examined episodic memory feeling-of-knowing (FOK) ratings in 21 moderate to severe closed-head injury (CHI) participants (more than 1 year postinjury) and 21 controls. Participants studied 36 critical cue-target word pairs. Following a brief delay, they were asked to recall the target that corresponded to a given cue. Confidence ratings were made for recalled words, and FOK judgments were made for nonrecalled words in terms of the likelihood of recognizing the target word on a subsequent recognition test. CHI participants demonstrated less accurate recall but accurate ability to judge their recall performance (retrospective memory monitoring). They also demonstrated intact FOK judgments when providing binary judgments but demonstrated difficulties making finer discriminations on an ordinal scale (prospective memory monitoring). These findings suggest that memory monitoring is not a unitary construct. It is proposed that CHI participants may display intact memory monitoring when predictions are based on familiarity assessment but not when continued probing for additional episodic information is required. (PsycINFO Database Record (c) 2010 APA, all rights reserved)