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Objective: To further understanding of text comprehension abilities in Alzheimer's disease (AD), a think-aloud protocol was used to examine the role of inferencing and the memory operations used to produce inferences., Method: Twenty participants with AD and 20 cognitively healthy older adults (OA) read narratives, pausing to talk aloud after each sentence. A verbal protocol analysis developed by Trabasso and Magliano (1996a) was used to code participants' utterances into inferential and noninferential clause types; inferential statements were then coded to identify the memory operation used in their generation., Results: Compared with OA controls, the AD participants showed poorer story comprehension, d = 2.0, produced fewer inferences, d = .67, and were less skilled at providing explanations of story events, d = 1.27, and in using prior text information to explain outcomes, d = .90. The AD group also appeared to rely more on the activation of world knowledge, d = .58, which contributed to less effective inferences and produced more incoherent noninferential statements, d = 1.05. Poorer text comprehension for the AD group was associated with poorer verbal memory abilities, r's > .55, and poorer use of prior text events when producing explanatory inferences, r = .42., Conclusions: The findings suggest that the memory difficulties of the AD group appear to be an important cognitive factor interfering with their ability to integrate story events through the use of inferences and to create a global coherence to support text comprehension.

A performance-prediction paradigm was used to examine metamemory abilities in 27 individuals with amnestic mild cognitive impairment (MCI), 14 individuals with nonamnestic MCI, and 41 controls. To assess memory self-awareness, participants predicted the number of words they would remember before completing a list-learning memory task. Memory self-monitoring was evaluated by participants' ability to increase the accuracy of their predictions after experience with the list-learning task. As expected, participants with amnestic MCI demonstrated poorer memory abilities than the controls and participants with nonamnestic MCI. The amnestic MCI group also correctly predicted that they would recall less information than controls. Furthermore, both MCI groups showed accurate awareness of how differing task demands influence recall and successfully modified their memory predictions to be more accurate following task exposure. These findings revealed that individuals with amnestic and nonamnestic MCI were able to competently assess the demands of an externally driven metamemorial situation and utilize experience with a task to accurately update memory self-knowledge. Accurate metamemory skills may facilitate the ability of individuals with MCI to benefit from targeted behavioral interventions focused on utilizing compensatory strategies for everyday memory problems.

The pervasive sensing technologies found in smart homes offer unprecedented opportunities for providing health monitoring and assistance to individuals experiencing difficulties living independently at home. A primary challenge that needs to be tackled to meet this need is the ability to recognize and track functional activities that people perform in their own homes and everyday settings. In this paper, we look at approaches to perform real-time recognition of Activities of Daily Living. We enhance other related research efforts to develop approaches that are effective when activities are interrupted and interleaved. To evaluate the accuracy of our recognition algorithms we assess them using real data collected from participants performing activities in our on-campus smart apartment testbed.

Objective: To examine memory self-awareness abilities in individuals with moderate-to-severe traumatic brain injury (TBI) using both 'online assessment' and 'offline assessment' methodologies., Design and Methods: Participants were 23 individuals with TBI and 23 controls matched on age, education and sex. Online assessment of memory was assessed by comparing the predicted amount of information participants expected that they would remember following trial 1, trial 5 and a 20-minute delay with actual memory performance on list-learning and visuospatial memory tests. Offline assessment of memory involved contrasting self-ratings provided by TBI participants about their everyday memory functioning with ratings from knowledgeable informants and with performance on objective memory tests., Results: Individuals with TBI displayed poorer recall for newly learned information than control participants, but no significant group differences emerged in the online assessment of memory self-awareness. The offline assessment comparisons similarly demonstrated that the individuals with TBI exhibited accurate awareness for their everyday memory performances., Conclusions: These findings suggest intact memory self-awareness following moderate-to-severe TBI during the early stages of recovery (2-10 months post-injury).

In the current study, we introduce the Item-Specific Deficit Approach (ISDA), a novel method for characterizing memory process deficits in list-learning data. To meet this objective, we applied the ISDA to California Verbal Learning Test (CVLT) data collected from a sample of 132 participants (53 healthy participants and 79 neurologically compromised participants). Overall, the ISDA indices measuring encoding, consolidation, and retrieval deficits demonstrated advantages over some traditional indices and indicated acceptable reliability and validity. Currently, the ISDA is intended for experimental use, although further research may support its utility for characterizing memory impairments in clinical assessments.

We examined memory self-awareness and memory self-monitoring abilities during inpatient rehabilitation in participants with moderate to severe traumatic brain injury (TBI). A total of 29 participants with moderate to severe TBI and 29 controls matched on age, gender, and education completed a performance prediction paradigm. To assess memory self-awareness, participants predicted the amount of information they would remember before completing list-learning tasks and visual-spatial memory tasks. Memory self-monitoring was assessed by participants' ability to increase accuracy of their predictions after experience with the tests. Although the TBI participants performed more poorly than controls on both episodic memory tasks, no significant group differences emerged in memory self-awareness or memory self-monitoring. The TBI participants predicted that their memory performances would be poorer than that of controls, accurately adjusted their predictions in accordance with the demands of the tasks, and successfully modified their predictions following experience with the tasks. The results indicate that moderate to severe TBI individuals in the early stages of recovery can competently assess the demands of externally driven metamemorial situations and utilize experience with task to accurately update their knowledge of memory abilities.

Accurate time estimation abilities are assumed to play an important role in efficient performance of many daily activities. The authors investigated the role of episodic memory impairment in temporal perception using a prospective verbal time estimation paradigm. Verbal time estimations were made for filled intervals both within (i.e., <30 s) and beyond the time frame of working memory. In Experiment 1, the verbal time estimates of 24 individuals with mild cognitive impairment (MCI) were comparable with those of age-matched controls at both short and long (i.e., >30 s) intervals. The verbal time estimates of both older adult groups, however, deviated more significantly from true time when compared with younger adult controls. In Experiment 2, 17 individuals with Alzheimer's disease (AD) demonstrated greater error and variability in their time estimates, but no disproportionate differences emerged between short- and long-duration estimates when compared with age-matched controls. The findings did not support a noteworthy role for episodic memory impairment in temporal perception but rather elucidated a significant effect of normal aging, as well as a detrimental effect of AD on temporal perception.

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.

The purpose of this study was to determine the effectiveness of semantic cues provided at encoding and during retention for older adults' memory. For the California Verbal Learning Test-II, participants received semantic or nonsemantic cues that were varied across groups at encoding and during the retention interval. Provision of a semantic cue at encoding led to greater semantic clustering at learning, but not increased recall performance. Providing a semantic cue during the retention interval led to better delayed free recall and greater semantic clustering. No group differences in recall or semantic clustering were found at delayed cued recall. The current findings suggest that semantic cues can be beneficial for recalling unstructured information when administered during the retention interval.

The ability to switch rapidly and fluidly between tasks is an important component of many everyday activities. In this study, we used a predictable, externally cued task-switching paradigm to investigate executive control processes in individuals with mild cognitive impairment (MCI). Participants were 26 individuals with amnestic MCI and 26 healthy older adult (OA) controls. In the mixed-task trials, participants switched between classifying whether a digit was odd/even or a letter was a consonant/vowel on every fourth trial. In the single-task trials, participants completed only the digit task or letter task throughout the entire block. Task switching costs were decomposed into nonswitch costs, which reflect the dual nature of the task, and switch costs, which reflect set-shifting abilities. The results revealed that the MCI group was not affected more than the healthy OAs by the requirement of keeping two tasks sets active in working memory (nonswitch costs). In contrast, the cost of switching between the two tasks was significantly greater for the MCI group compared with the OA controls (switch costs). Future research is needed to better understand the nature and implications for daily living of the greater switch costs found for individuals with MCI. (JINS, 2009, 15, 103-111.).

The pervasive sensing technologies found in smart homes offer unprecedented opportunities for providing health monitoring and assistance to individuals experiencing difficulties living independently at home. A primary challenge that needs to be tackled to meet this need is the ability to recognize and track functional activities that people perform in their own homes and everyday settings. In this paper we look at approaches to perform real-time recognition of Activities of Daily Living. We enhance other related research efforts to develop approaches that are effective when activities are interrupted and interleaved. To evaluate the accuracy of our recognition algorithms we assess them using real data collected from participants performing activities in our on-campus smart apartment testbed.

This pilot study examines the efficacy of a group memory notebook intervention. Five individuals with very mild dementia and 4 spouses who served as coaches attended 14 group treatment sessions. Therapists use educational strategies and learning activities packets to teach memory notebook use. At posttreatment, coaches report fewer symptoms of depression, and participants with very mild dementia report greater confidence in ability to obtain support. Modified laboratory memory testing reveals that participants with dementia demonstrate improved posttreatment memory scores because of increased note-taking behavior and more frequent referencing of notes. Although more frequent everyday memory strategies use is reported at posttreatment, this does not translate into reports of fewer everyday memory failures or greater everyday independence for the participants with dementia. This study demonstrates that a multidyad group intervention can successfully be used to teach patients with very mild dementia to use a memory notebook, with beneficial effects for both members of the care dyad.

Primary Objective: This study used an object definitions test to examine semantic memory and the organization of semantic knowledge during the early stage of recovery from traumatic brain injury (TBI)., Research Design: Twenty-four participants with moderate-to-severe TBI and 24 controls described three living and three non-living objects as if they were describing them to someone who had never heard of or seen such things before., Methods and Procedures: The verbal definitions were examined at a feature level and for whether they communicated the core concept (i.e. could a blind rater identify the object)., Main Outcomes and Results: Compared to the control group, the TBI group less often provided object definitions that communicated the core concept and included superordinate category information. The TBI group also produced a smaller proportion of physical specific features and the production of fewer physical specific features was associated with lower production of the core concept. Despite these group differences, both groups produced more specific feature information about the objects than general feature information; and more physical specific features for living objects and associative specific features for non-living objects., Conclusions: The findings were interpreted as suggesting a decreased efficiency in ability to access semantic information following moderate-to-severe TBI, which influenced core concept production, despite intact organization of semantic knowledge.

The ability to accurately estimate the passage of time plays an important role in helping to structure daily activities. In this study, we used a prospective verbal time estimation paradigm to investigate time perception in 27 moderate to severe traumatic brain injury (TBI) participants and 27 controls. Verbal time estimations were made for filled intervals both within (i.e., <30 s) and beyond the time frame of working memory. We found that the TBI participants exhibited normal or near-normal estimates of time passage for duration up to 25 s. In contrast, for durations that exceeded working memory, the TBI group perceived less time as having passed than actually had passed as the TBI group significantly underestimated time when compared to controls. This pattern of data was interpreted as being due to episodic memory dysfunction.

Across three experiments, the effects of age and normative information on memory prediction accuracy were examined. In Experiment 1, younger and older adults were given an arbitrary midpoint anchor and made global predictions about how they expected to perform on subsequent verbal, visual, and name-face memory tasks. In Experiment 2, the normative information was varied by providing participants with a midpoint anchor, accurate anchor, or no anchor. Across both experiments, older adults successfully adjusted their predictions in accordance with the task demands, regardless of the type of normative information given. In Experiment 3, older adults' prediction accuracy was measured at a 5-year follow-up. Memory performance predictions were found to be just as accurate as they had been at the first assessment. In general, the findings indicate that older adults were as accurate as younger adults in assessing their memory performance abilities. Older adults also did not operate on a negative stereotype of global cognitive decline with age, as they provided varying performance estimates across the different domains and types of memory tasks.

Primary Objective: Research on the ecological validity of neuropsychological tests of executive functioning has been limited by disagreement in the number and make-up of the factors underlying the dysexecutive syndrome. The current study sought to determine whether similar components of everyday executive dysfunction are being measured by the Dysexecutive Questionnaire (DEX) and the Brock Adaptive Functioning Questionnaire (BAFQ)., Research Design: Using the same sample, a factor analysis of the DEX and the BAFQ was conducted to determine whether a similar underlying factor structure for the dysexecutive syndrome would be found across measures., Methods and Procedures: The significant others of 46 adults with varying neurological conditions completed the DEX and BAFQ., Main Outcomes and Results: Behavioural inhibition, goal-directed behaviour/intentionality and executive memory/cognition were found to be key underlying factors of the everyday dysexecutive syndrome identified by both measures. The remaining factors were divergent., Conclusions: Consistent with prior research, this study indicates that the dysexecutive syndrome is multi-factorial. This research further highlights core factors associated with real world executive functioning deficits and demonstrates that the dysexecutive syndrome has distinct sub-components that transcend the specific questionnaire measure used.

Age differences in memory performances on a conceptually driven task, the category exemplar generation (CEG) test, were investigated. Thirty-six younger adults and 36 healthy older adults studied word lists in full and divided attention conditions. Recall was tested with category names. The process-dissociation procedure was used to derive estimates of controlled and automatic memory. Old-old adults (70-84 years) exhibited poorer conscious recollection than both younger (18-24) and young-old adults (59-69). In contrast, no age differences were found in estimates of automatic memory. For the younger and older adults, the divided encoding manipulation reduced both the consciously controlled and automatic estimates of memory. The results suggest that the few prior findings of age deficits in priming on the CEG may have been an artifact of contamination from conscious retrieval processes. They also indicate that the opportunity for greater semantic processing enhances the conceptual priming of both younger and older adults.

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.

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.

We examined the long-term retention of a learned automatic cognitive process in 17 severe TBI participants and 10 controls. Participants had initially received extensive consistent-mapping (CM) training (i.e., 3600 trials) in a semantic category visual search task (Schmitter-Edgecombe & Beglinger, 2001). Following CM training, TBI and control groups demonstrated dramatic performance improvements and the development of an automatic attention response (AAR), indicating task-specific and stimulus-specific skill learning. After a 5- or 10-month retention interval, participants in this study performed a New CM task and the originally trained CM task to assess for retention of task-specific and stimulus-specific visual search skills, respectively. No significant group differences were found in the level of retention for either skill type, indicating that individuals with severe TBI were able to retain the learned skills over a long-term retention interval at a level comparable to controls. Exploratory analyses revealed that TBI participants who returned at the 5-month retention interval showed nearly complete skill retention, and greater skill retention than TBI participants who returned at the 10-month interval, suggesting that "booster" or retraining sessions may be needed when a skill is not continuously in use.

The current study investigated ways to improve the ecological validity of the neuropsychological assessment of executive functioning through the formal assessment of compensatory strategies and environmental cognitive demands. Results indicated that the group of executive functioning tests (i.e., Trail Making Test, Wisconsin Card Sorting Test, Stroop, and Controlled Oral Word Association Test) accounted for 18-20% of the variance in everyday executive ability as measured by the Dysexecutive Questionnaire and Brock Adaptive Functioning Questionnaire. The addition of extra-test variables significantly increased the variance in everyday executive ability accounted for. The current study adds to the literature on the ecological validity of executive functioning assessment by highlighting the importance of extra-test variables when trying to understand the complex relationship between cognitive testing and real world performance.

Within a theoretical framework for rehabilitation that distinguishes between automatic and controlled processes, this article reviews basic science research and addresses the following issues: What cognitive abilities remain relatively intact after severe traumatic brain injury, and how can we incorporate intact skills into rehabilitative techniques? The reviewed research indicates that individuals with severe traumatic brain injury (a) generally perform similar to controls on cognitive tasks (or task components) that require automatic and implicit processes as opposed to consciously controlled processes; (b) can learn through implicit learning mechanisms; and (c) can acquire and use automatic processes in complex, cognitive task performance.

A think-aloud method was used to examine the content of information available to working memory during narrative comprehension in a CHI population. Twenty severe CHI participants (>1 year post-injury) and 20 controls talked aloud after they read each sentence of story narratives. Trabasso and Magliano's (1996a) verbal protocol analysis was then used to code for the production of inferential and non-inferential clauses and the memory operations that supported inferential clause production. We found that CHI and control groups produced a comparable number of clauses, that inferences dominated narrative comprehension, and that both groups produced more explanatory inferences than predictive or associative inferences. Despite these qualitative similarities, the CHI group demonstrated poorer comprehension, generated proportionately fewer inferences, relied less on retrieval as a memory source for explanatory inferences, and produced more non-inferential clauses and associative inferences.

Objective: To examine the accuracy of memory self-awareness and memory self-monitoring abilities in participants with severe closed-head injury (CHI)., Design and Methods: A performance-prediction paradigm was used to evaluate meta-memory abilities in 31 participants with severe CHI (>1 year post-injury) and 31 controls. To assess memory self-awareness, before completing story recall, visual reproduction and list learning memory tasks, participants predicted the amount of information they would remember for each task. Memory self-monitoring was evaluated by examining participants' ability to increase the accuracy of their predictions following experience with each memory task., Results: Although participants with CHI exhibited poorer recall than controls, they were equally aware of how differing task demands influence recall. They also successfully modified their predictions following task exposure., Conclusions: Meta-memory was better preserved than actual memory performance. It may be possible to build on meta-memory skills to help patients with CHI more consistently use strategies that aid memory performance.

Age-related declines in working memory performance have been associated with deficits in inhibition, strategy use, processing speed, and monitoring. In the current study, cross-sectional and longitudinal methodologies were used to investigate the relative contribution of these components to age-related changes in working memory. In Experiment 1, a sample of 140 younger and 140 older adults completed an abstract design version of the Self-Ordered Pointing Task modeled after Shimamura and Jurica (1994). Experiment 1 revealed that only processing speed and monitoring explained age differences in SOPT performance. Participants in Experiment 2 were 53 older adults who returned 4 years after the initial testing and 53 young adults. A task that assessed the ability to generate and monitor an internal series of responses as compared to an externally imposed series of responses was also administered. Experiment 2 replicated the key findings from Experiment 1 and provided some further evidence for age-related internal monitoring difficulties. Furthermore, the exploratory longitudinal analysis revealed that older age and lower intellectual abilities tended to be associated with poorer performance on the SOPT at Time 2.

Twenty-four severe closed-head injury (CHI) participants and 24 controls completed event-based prospective memory tasks concurrently with an ongoing working memory task. The event cue was either integrated with the ongoing working memory task (focal cue) or peripheral to it. Prospective remembering was poorer for the CHI group in both the focal- and peripheral-cue conditions. The groups did not differ on the ongoing task. The peripheral cue and the integrated focal cue also did not differ in ability to trigger prospective remembering. The results suggest that, even with highly salient event cues, severe CHI participants (> 1 year postinjury) are more likely than controls to exhibit prospective memory failures. The data revealed a link between CHI participants' prospective memory failures and momentary lapses of intention.

A variant of the list method directed forgetting procedure was used to examine the role of inhibition in memory performance following severe closed-head injury (CHI). Twenty-four participants with severe CHI and 24 controls studied picture and word stimuli in both forget and remember conditions. Memory testing for the to-be-forgotten and to-be-remembered items consisted of a free-recall test followed by a source-monitoring task. Despite poorer recall performance, the participants with CHI exhibited a directed forgetting effect similar to that in controls. Item recognition scores indicated that the inhibited items were not forgotten but rather were items whose accessibility had been lowered. These findings suggest that residual memory deficits in patients with severe CHI are unlikely to reflect inefficient retrieval inhibition., (((c) 2004 APA, all rights reserved))

Evaluating the ecological validity of neuropsychological tests has become an increasingly important topic over the past decade. In this paper, we provide a comprehensive review of the research on the ecological validity of neuropsychological tests, as it pertains to everyday cognitive skills. This review is presented in the context of several theoretical issues facing ecological validity research. Overall, the research suggests that many neuropsychological tests have a moderate level of ecological validity when predicting everyday cognitive functioning. The strongest relationships were noted when the outcome measure corresponded to the cognitive domain assessed by the neuropsychological tests. Several other factors that may moderate the degree of ecological validity established for neuropsychological tests are in need of further exploration. These factors include the effects of the population being tested, the approach utilized (verisimilitude vs. veridicality), the person completing the outcome measure (significant other vs. clinician), illness severity, and time from injury until evaluation. In addition, a standard measurement of outcome for each cognitive domain is greatly needed to allow for comparison across studies.

This study investigated executive aspects of working memory in a severe closed-head injured (CHI) population. Thirty-four severe CHI participants (>1 year postinjury) and 34 controls completed an abstract design version of Petrides and Milner's (1982) self-ordered pointing task. CHI participants made more errors than controls on the 16-item trial, but not the 9-item trial. Both CHI and control participants were able to make use of strategic processing to improve SOPT performance. As anticipated, errors on the SOPT were associated with another measure of working memory (i.e., Reading Span Test) for the control group. In contrast, for the CHI participants, errors on the SOPT were associated with a measure of delayed visual memory (i.e., Wechsler Memory Scale-Revised Visual Reproduction II subtest). Our findings suggest that, as a group, the primary factor resulting in poorer SOPT performance by the CHI group was a memory deficit and not the ability to utilize executive aspects of working memory.

Thirty severe closed-head injured (CHI) participants (more than 1 year postinjury) and 30 matched controls completed eight different cognitive activities. Participants' free recall and recognition of the activities provided a measure of content memory. Temporal order memory was assessed with a reconstruction task. CHI participants recalled and recognized fewer activities than did controls. However, the CHI and control groups did not differ in temporal order memory. For both groups, recognition memory was not correlated with temporal order memory. These results demonstrate intact temporal order memory for performed activities in a severe CHI population, and support the notion of separate processing of content memory and order information. Issues related to automaticity and the roles of the frontal lobes in temporal order memory are also discussed.

Objective: To examine whether a behavioural measure of frontal lobe functioning, the Brock Adaptive Functioning Questionnaire (BAFQ), could predict employment status following traumatic brain injury (TBI)., Design: A discriminant function analysis was conducted to determine the ability of the BAFQ, along with other factors, to predict occupational status post-injury., Methods: Sixty-one TBI survivors completed a background information questionnaire, the BAFQ, and an employment status rating scale., Results: A factor analysis of the BAFQ sub-scales revealed two factors, one related to functioning in the orbitofrontal area, and one related to dorsolateral frontal lobe functioning. These two factors, along with background information, were entered into a discriminant function analysis, revealing a 77.4% accuracy rate in predicting occupational status post-injury., Conclusions: Demographic variables were found to differentiate employed from unemployed survivors. The BAFQ appeared useful in differentiating survivors who may return to their pre-injury employment level from those who may require modified employment.

This study suggests that perceptually based implicit learning may either be preserved following a severe closed-head injury (CHI) or recover within the 1st year. Nineteen severe CHI patients and 19 controls searched visual matrices and indicated the quadrant location of a target. Participants were exposed to the following covariation pattern: AAAABAAA. For Covariation A blocks, the matrices systematically co-occurred with a unique location of the target. This relationship was altered for the B block. Despite CHI participants' overall slower response times (RTs), both groups demonstrated the expected decline in RTs across the first 4 Covariation A blocks followed by an increase when the covariation changed. Both groups also exhibited retention of their learning after a 20-min delay. Explicit knowledge tests indicated that participants lacked awareness for the covariation.