Pre-existing Group Differences Research Articles

Untangling the tingle: Investigating the association between the Autonomous Sensory Meridian Response (ASMR), neuroticism, and trait & state anxiety.

The Autonomous Sensory Meridian Response (ASMR) is an intensely pleasant tingling sensation originating in the scalp and neck and is elicited by a range of online video-induced triggers. Many individuals now regularly watch ASMR videos to relax, and alleviate symptoms of stress and insomnia, all which are indicative of elevated levels of anxiety. Emerging literature suggests that ASMR-capable individuals are characterised by high trait neuroticism, which is associated with a tendency to experience negative emotional states such as anxiety. To date however no literature has empirically linked these personality constructs and watching ASMR videos on the effect of reducing anxiety. In the current study, 36 ASMR-experiencers and 28 non-experiencers watched an ASMR video, and completed assessments of neuroticism, trait anxiety, and pre- / post-video state anxiety. MANCOVA with Group as the independent measures factor showed that ASMR-experiencers had significantly greater scores for neuroticism, trait anxiety, and video engagement than non-experiencers. Pre-video state anxiety was also significantly greater in the ASMR-experiencers and was significantly attenuated on exposure to the ASMR video, whereas non-experiencers reported no difference in state anxiety pre- and post-video. Thus, watching ASMR alleviated state anxiety but only in those who experienced ASMR. Subsequent mediation analyses identified the importance of pre-existing group differences in neuroticism, trait and (pre-video) state anxiety in accounting for the group difference in the reduction of state anxiety. The mediation analysis further lends support for watching ASMR videos as an intervention for the reduction of acute state anxiety. Future areas for research are discussed.

Remote elementary education: a comparative analysis of learner development (part 1)

PurposeThe purpose of this two-part research was to investigate the effect of remote learning on student progress in elementary education. Part one, presented in this paper, examined achievement differences between learners in a fully remote learning environment and those in a hybrid setting.Design/methodology/approachA quantitative, quasi-experimental study with factorial design was used to investigate group differences in student achievement between the different learning environments. Ex-post-facto data from standardized test scores were utilized to examine in which ways the learning environment may have affected learner progress in two distinct subject areas crucial to elementary education: English language (ELA) and math.FindingsFindings revealed a significant difference between the two learning environments in both subject areas. While preexisting group differences, selection biases and testing inconsistencies could be effectively ruled out as potential causes for the observed differences, other factors such as developmental and environmental differences between the learning environments seemed to be influential. Therefore, the follow-on research aimed at further investigating and confirming the influence of such factors and will be presented in a Part 2 paper.Practical implicationsKnowledge of the observed differences in learning achievements between the different environments, as well as the factors likely causing them, may aid educators and school administrators in their decision processes when faced with difficult circumstances such as during the pandemic.Originality/valueWhen the SARS-CoV-2 virus started to rapidly spread around the globe, educators across the world were looking for alternatives to classroom instruction. Remote learning became an essential tool. However, in contrast to e-learning in postsecondary education, for which an abundance of research has been conducted, relatively little is known about the efficacy of such approaches in elementary education. Lacking this type of information, it seems that educators and administrators are facing difficult decisions when trying to align the often conflicting demands of public health, local politics and parent pressure with what may be best for student learning.

A Propensity Score Method for Investigating Differential Item Functioning in Performance Assessment.

This study introduces a novel differential item functioning (DIF) method based on propensity score matching that tackles two challenges in analyzing performance assessment data, that is, continuous task scores and lack of a reliable internal variable as a proxy for ability or aptitude. The proposed DIF method consists of two main stages. First, propensity score matching is used to eliminate preexisting group differences before the test, ideally creating equivalent groups as in a randomized experimental study. Then, linear mixed effects models are adopted to perform DIF analysis based on the matched data set. We demonstrate this propensity DIF method using a high-stakes functional English language proficiency test. DIF due to education was investigated in the writing component, which consists of two continuously scored performance-based tasks. Although the proposed method is demonstrated in the context of language testing, it can be applied to other types of performance assessments.

Sleep spindle and psychopathology characteristics of frequent nightmare recallers

Idiopathic nightmares are a common disturbance of rapid eye movement sleep (REM) sleep, but studies of comorbid pathologies and sleep architecture suggest that non-REM (NREM) sleep is also affected. Sleep spindles are a NREM sleep characteristic associated with both pathophysiology and sleep-dependent memory consolidation, yet they have not been evaluated in frequent nightmare recallers. The morning naps of 38 participants with frequent idiopathic nightmares (mean age: 23.7 ± 3.78 years) and 25 age- and sex-matched controls (23.9 ± 3.65 years) were recorded and their sleep evaluated. A custom spindle detector assessed NREM sleep stage 2 (N2) sleep spindles on six electroencephalogram (EEG) derivations (F3, F4, C3, C4, O1, and O2) for density (number spindles/N2 time), mean frequency, and amplitude. Total spindles (10–16 Hertz (Hz) range), slow spindles (10–12.79 Hz), and fast spindles (12.8–16 Hz) were all assessed separately. Compared with the Control group, the Nightmare group had longer N2 sleep latency and a marginally greater %N2 sleep. The Nightmare group also had a lower than normal density of slow spindles in most EEG derivations, a higher density of fast spindles in frontal derivations, and an elevated fast spindle oscillatory frequency—“faster fast” spindles—mainly in central derivations. These differences withstood controls for pre-existing group differences in depression. Correlational analyses demonstrated a further pattern of group differences by which higher pathology scores were associated with higher slow spindle densities and slower spindle frequencies for the Nightmare but not the Control group. A similar pattern was observed for some dream content measures, ie, the Nightmare group showed positive correlations of slow spindle density with dreamed fear and word count and negative correlations with dreamed positive emotion. Conversely, the Control group showed opposite trends. Results thus demonstrate abnormalities in the composition of N2 sleep—and especially in N2 spindles—among frequent nightmare recallers and link these abnormalities to both trait (psychopathology) and state (dream content) factors. Spindle findings for psychopathology resemble, but are not identical with, previous findings for patients with major depression, social anxiety, and schizophrenia and are thus consistent with an explanation implicating spindles as trait markers of psychopathology. Correlational analyses go beyond a trait explanation to suggest several possible state-based explanations involving memory consolidation mechanisms, specifically, the possibility that spindles index either emotional or verbal task-based processes.

Propensity score analysis: an alternative statistical approach for HRD researchers

Purpose This paper aims to introduce matching in propensity score analysis (PSA) as an alternative statistical approach for researchers looking to make causal inferences using intact groups. Design/methodology/approach An illustrative example demonstrated the varying results of analysis of variance, analysis of covariance and PSA on a heuristic data set. The three approaches were compared by results and violations of statistical assumptions. Findings Through the illustrative example, it is demonstrated how different statistical approaches can produce varied results. Only PSA mitigated pre-existing group differences without violating the assumption of independence. Originality/value This paper attempts to answer calls in the literature for more robust statistical methodologies to better inform human resource development practice and theory.

Evaluation and applications of the clinically significant change method with the Violence Risk Scale-Sexual Offender version: implications for risk-change communication.

We examined the use of the clinically significant change (CSC) method with the Violence Risk Scale-Sexual Offender version (VRS-SO), and its implications for risk communication, in a combined sample of 945 treated sexual offenders from three international settings, followed up for a minimum 5 years post-release. The reliable change (RC) index was used to identify thresholds of clinically meaningful change and to create four CSC groups (already okay, recovered, improved, unchanged) based on VRS-SO dynamic scores and amount of change made. Outcome analyses demonstrated important CSC-group differences in 5-year rates of sexual and violent recidivism. However, when baseline risk was controlled via Cox regression survival analysis, the pattern and magnitude of CSC-group differences in sexual and violent recidivism changed to suggest that observed variation in recidivism base rates could be at least partly explained by pre-existing group differences in risk level. Implications for communication of risk-change information and applications to clinical practice are discussed.

Stress in Latino families following an adolescent's childbearing: effects on family relationships and siblings.

This study examined how increased stress in Latino families following an adolescent's childbearing impacts family relationships and the adolescent's siblings. Participants were 243 Mexican American youth (mean age: 13.7 years; 62% girls), or 121 youth who had a pregnant adolescent sister and 122 youth who had an adolescent sister who had never been pregnant. Youth and their mothers were studied at 4 time points across 15 months: The families of pregnant adolescents were studied when the adolescent sister was in her third trimester of pregnancy, and at 2 months, 6 months, and 12 months postpartum; the families of never-pregnant adolescents were studied at like intervals. Individual fixed-effects structural equation models were computed, which control for earlier measures of study constructs and thereby reduce omitted variable bias from preexisting family group differences. Results showed that an adolescent's childbearing was related to increases in family stress, which were related to increases in mothers' harsh parenting and mother-sibling conflict, which, in turn, were related to subsequent increases in siblings' problem behavior. Multiple group analyses revealed that the pathways through which a teenager's childbearing influences siblings operate similarly for girls and boys. Tests of an alternate ordering of model variables indicated a poor fit with the data. Findings provide evidence that the accumulation of stressful family changes following an adolescent's childbearing can negatively impact siblings. Findings also elucidate how family-level stress and disruption experienced across a family transition trickle down to affect family relationships and, in turn, child family members.

The Effectiveness of Online and Blended Learning: A Meta-Analysis of the Empirical Literature

Background/Context Earlier research on various forms of distance learning concluded that these technologies do not differ significantly from regular classroom instruction in terms of learning outcomes. Now that web-based learning has emerged as a major trend in both K–12 and higher education, the relative efficacy of online and face-to-face instruction needs to be revisited. The increased capabilities of web-based applications and collaboration technologies and the rise of blended learning models combining web-based and face-to-face classroom instruction have raised expectations for the effectiveness of online learning. Purpose/Objective/Research Question/Focus of Study This meta-analysis was designed to produce a statistical synthesis of studies contrasting learning outcomes for either fully online or blended learning conditions with those of face-to-face classroom instruction. Population/Participants/Subjects The types of learners in the meta-analysis studies were about evenly split between students in college or earlier years of education and learners in graduate programs or professional training. The average learner age in a study ranged from 13 to 44. Intervention/Program/Practice The meta-analysis was conducted on 50 effects found in 45 studies contrasting a fully or partially online condition with a fully face-to-face instructional condition. Length of instruction varied across studies and exceeded one month in the majority of them. Research Design The meta-analysis corpus consisted of (1) experimental studies using random assignment and (2) quasi-experiments with statistical control for preexisting group differences. An effect size was calculated or estimated for each contrast, and average effect sizes were computed for fully online learning and for blended learning. A coding scheme was applied to classify each study in terms of a set of conditions, practices, and methodological variables. Findings/Results The meta-analysis found that, on average, students in online learning conditions performed modestly better than those receiving face-to-face instruction. The advantage over face-to-face classes was significant in those studies contrasting blended learning with traditional face-to-face instruction but not in those studies contrasting purely online with face-to-face conditions. Conclusions/Recommendations Studies using blended learning also tended to involve additional learning time, instructional resources, and course elements that encourage interactions among learners. This confounding leaves open the possibility that one or all of these other practice variables contributed to the particularly positive outcomes for blended learning. Further research and development on different blended learning models is warranted. Experimental research testing design principles for blending online and face-to-face instruction for different kinds of learners is needed.

Effects of Noxious Versus Innocuous Thermal Stimulation on Lower Extremity Motor Recovery 3 Months After Stroke

ObjectiveTo examine the effects of thermal stimulation (TS) on the lower extremity (LE) movement and function in patients with stroke. DesignA double-blinded randomized controlled trial. SettingA university hospital. ParticipantsPatients (N=34) at least 3 months after stroke were randomly assigned into the experimental and the control groups. InterventionsIn addition to regular rehabilitation, the experimental group received a 30-minute noxious TS protocol (heat pain 46–47°C/cold pain 2–3°C) 3days/wk for 8 weeks, and the control group received a 30-minute innocuous TS protocol (heat 40–41°C/cold 23–24°C) 3d/wk for 8 weeks. Main Outcome MeasuresThe Low Extremity subscale of the Stroke Rehabilitation Assessment of Movement (LE-STREAM), the Mobility subscale of STREAM (Mob-STREAM), the Functional Ambulation Category (FAC), the Barthel Index (BI), the Postural Assessment Scale for Stroke Patients (PASS), and the Modified Ashworth Scale (MAS) were administered by a blinded rater at baseline, posttreatment (8wk), and follow-up (12wk). ResultsTwenty-three participants completed the study protocol and all outcome measurements. No preexisting group differences between the experimental group (n=11) and the control group (n=12) were found on demographic and clinical variables. Compared with baseline, the experimental group showed significant improvements at posttreatment and follow-up on the LE-STREAM, Mob-STREAM, FAC, and BI (P<.05) while the control group showed no significant improvements for all outcome measures. As for the between-group comparison, significant differences were seen at follow-up (12wk) on the LE-STREAM, Mob-STREAM, BI, and MAS. ConclusionsOur findings indicate that an 8-week program of noxious TS combined with a traditional stroke rehabilitation program can improve the LE-related movement and function in patients with stroke for more than 3 months.

The Younger Siblings of Childbearing Adolescents: Parenting Influences on Their Academic and Social-Emotional Adjustment

The younger siblings of childbearing adolescents have poorer school outcomes and exhibit more internalizing and externalizing problems compared to their peers without a childbearing sister. We test a model where living with an adolescent childbearing sister constitutes a major family stressor that disrupts mothers' parenting and well-being, and through which, adversely affect youths' adjustment. Data came from 243 Latino younger siblings (62% female, M age 13.7 years) and their mothers, 121 of whom lived with a childbearing adolescent sister and 122 of whom did not. Individual fixed-effects models controlled for earlier measures of each respective model construct, thereby reducing omitted variable bias from pre-existing group differences. Results show that, for boys, the relationship between living with a childbearing adolescent sister and youth outcomes was sequentially mediated through mothers' stress and parenting (i.e., monitoring and nurturance). For girls, however, the relationship was mediated through mothers' monitoring only. Findings elucidate the within-family processes that contribute to the problematic outcomes of youth living with childbearing adolescent older sisters.

How Professional Development in Project Lead the Way Changes High School STEM Teachers’ Beliefs about Engineering Education

This quasiexperimental study measured the impact of Project Lead the Way (PLTW) instruction and professional development training on the views and expectations regarding engineering learning, instruction and career success of nascent precollege engineering teachers. PLTW teachers’ initial and changing views were compared to the views exhibited by a matching group of high school STEM teachers. The primary instrument was the Engineering Beliefs and Expectation Instruments for Teachers (EEBEIT), which included Likert scale items, contextualized judgments about fictional student vignettes, and demographic items. Teachers’ baseline survey responses, on average, revealed the importance of academic achievement on teachers’ decision making about who should enroll in future engineering classes and their predictions of who would be most likely to succeed in an engineering career. When making implicit comparisons between students who differed by SES, teachers generally favored enrollment and predicted more career success of high SES students. SES was excluded as a factor in the judgments of all participating teachers when explicitly probed, however. Preexisting group differences showed that budding PLTW teachers reported on STEM integration in their classes with greater frequency than control teachers, while control teachers agreed more strongly about the prerequisite role of high scholastic achievement for engineering studies. Finally, an analysis of teachers’ changing views indicated that nascent PLTW teachers increased their reporting of effective STEM integration over time, above and beyond preexisting group differences and retesting effects. In light of these data we explore the challenges of implementing effective STEM integration in high school classrooms, examine issues of attracting underrepresented students to engineering, and discuss some of the inherent tensions of engineering education at the K12 level.

Black–white differences in positive outcome expectancies for crime: A study of male federal prison inmates

Purpose This study was designed to assess whether black inmates hold more positive outcome expectancies for crime than white inmates in an effort to inform the debate on the nature of well documented differences in criminal involvement between blacks and whites. Methods Positive outcome expectancies for crime were measured in 393 black male inmates and 154 white male inmates housed in a medium security federal correctional institution using the Outcome Expectancies for Crime (OEC: Walters, 2003b) inventory. Results Black inmates reported significantly stronger positive outcome expectancies for crime than white inmates after controlling for preexisting group differences in age, education, marital status, confining offense, response style, general criminal thinking, and negative outcome expectancies for crime. Anticipation of social benefits for crime in the form of love, respect, and security were particularly salient in distinguishing between black and white inmates. Conclusions It is speculated that an interaction of motivational (high achievement motivation), structural (blocked economic opportunities), and cultural (peer reinforcement) factors may be responsible for black–white differences in crime with important implications for theory, research, and clinical practice.

Screening for Malingering/Exaggeration of Psychiatric Symptomatology in Prison Inmates Using the PICTS Confusion and Infrequency Scales*

A sample of 76 federal prison inmates with a history or current complaints of significant psychiatric symptomatology at intake were followed for a period of 4-39 months by a psychologist who rated the inmate as malingering (n=12), substantially exaggerating (n=32), minimally exaggerating (n=23), or honestly reporting (n=9) signs and symptoms of schizophrenia, bipolar disorder, major depression, or severe anxiety disorder. The Confusion-revised (Cf-r) and Infrequency (INF) scales of the Psychological Inventory of Criminal Thinking Styles, which had been administered routinely at intake, revealed that only the INF successfully predicted malingering and exaggeration of psychiatric symptomatology even after pre-existing group differences in age, race, and overall criminal thinking were controlled. These results suggest that the INF scale can potentially serve as an effective initial screening measure for malingering/exaggeration in inmates presenting with mental health complaints.

Statistical Requirements for Properly Investigating a Null Hypothesis

Issues involved in the evaluation of null hypotheses are discussed. The use of equivalence testing is recommended as a possible alternative to the use of simple t or F tests for evaluating a null hypothesis. When statistical power is low and larger sample sizes are not available or practical, consideration should be given to using one-tailed tests or less conservative levels for determining criterion levels of statistical significance. Effect sizes should always be reported along with significance levels, as both are needed to understand results of research. Probabilities alone are not enough and are especially problematic for very large or very small samples. Pre-existing group differences should be tested and properly accounted for when comparing independent groups on dependent variables. If confirmation of a null hypothesis is expected, potential suppressor variables should be considered. If different methods are used to select the samples to be compared, controls for social desirability bias should be implemented. When researchers deviate from these standards or appear to assume that such standards are unimportant or irrelevant, their results should be deemed less credible than when such standards are maintained and followed. Several examples of recent violations of such standards in family social science, comparing gay, lesbian, bisexual, and transgender families with heterosexual families, are provided. Regardless of their political values or expectations, researchers should strive to test null hypotheses rigorously, in accordance with the best professional standards.

Applicability of a Video Intervention to Increase Informed Decision Making for Prostate-Specific Antigen Testing

To evaluate the applicability of an evidence-based video intervention to promote informed decision making for prostate cancer screening among African American men with different levels of health literacy. Forty nine African American men participated in interviewer-administered, pretest and posttest interviews between January and March 2008. Health literacy status was assessed with the Test of Functional Health Literacy in Adults. Repeated measures analysis of covariance (ANCOVA), McNemar or binomial distributions were computed to assess pretest and posttest differences in knowledge. Descriptive statistics were produced to describe participants' perceptions of the information presented in the video. Results indicated that men with functional health literacy had higher mean levels of prostate cancer screening knowledge at baseline than men with inadequate health literacy. The between-group (F2,44= 4.84; p = .013) and within-group (F1,44 = 5.16; p = .028) test results from repeated-measures ANCOVA indicated that preexisting group differences in prostate cancer knowledge had lessened after intervention exposure. Nearly all men rated the information presented in the video as credible (98%), trustworthy (96%), interesting (100%), understandable (94%), and complete (96%). Results from this exploratory study suggest that the video intervention is suitable for use with African American men with different health literacy characteristics in 2 counties in the greater Florida panhandle region. More research is recommended to evaluate the impact of the intervention on men's intentions to undergo screening and actual screening behavior.

Deployment-related severe fatigue with depressive symptoms is associated with increased glucocorticoid binding to peripheral blood mononuclear cells

Severe fatigue and co-morbid depressive symptoms are frequently reported by recently deployed military personnel. Stress can induce lasting changes in the negative feedback regulation of the hypothalamic–pituitary–adrenal axis (HPA-axis) and the regulation of the immune system by cortisol. Since these actions of cortisol are modulated via glucocorticoid receptors (GR), we investigated the effect of deployment and of deployment-related fatigue on glucocorticoid binding to peripheral blood mononuclear cells (PBMCs) in a prospective design. Psychological assessments and blood sample collection took place before and one and six months after deployment. Participants were selected from a larger group and assigned to three groups based on their level of fatigue and depressive symptoms six months after deployment. We compared fatigued participants without depressive symptoms ( n = 21), fatigued participants with depressive symptoms ( n = 14) and non-fatigued participants without depressive symptoms ( n = 21). Fatigued participants with depressive symptoms at six months after deployment had higher glucocorticoid binding to PMBCs than the other two groups at all three time points. Notably, this difference was already present before deployment. There was no effect of deployment on glucocorticoid binding to PBMCs. The observed differences in glucocorticoid binding were not related to pre-existing group differences in psychological symptoms. No group differences were observed in the composition of the PBMC population and plasma cortisol levels. These results indicate that high glucocorticoid binding to PBMCs might represent a vulnerability factor for the development of severe fatigue with depressive symptoms after a sustained period of stress, such as deployment.

The effects of video game playing on attention, memory, and executive control

Expert video game players often outperform non-players on measures of basic attention and performance. Such differences might result from exposure to video games or they might reflect other group differences between those people who do or do not play video games. Recent research has suggested a causal relationship between playing action video games and improvements in a variety of visual and attentional skills (e.g., [Green, C. S., & Bavelier, D. (2003). Action video game modifies visual selective attention. Nature, 423, 534–537]). The current research sought to replicate and extend these results by examining both expert/non-gamer differences and the effects of video game playing on tasks tapping a wider range of cognitive abilities, including attention, memory, and executive control. Non-gamers played 20+ h of an action video game, a puzzle game, or a real-time strategy game. Expert gamers and non-gamers differed on a number of basic cognitive skills: experts could track objects moving at greater speeds, better detected changes to objects stored in visual short-term memory, switched more quickly from one task to another, and mentally rotated objects more efficiently. Strikingly, extensive video game practice did not substantially enhance performance for non-gamers on most cognitive tasks, although they did improve somewhat in mental rotation performance. Our results suggest that at least some differences between video game experts and non-gamers in basic cognitive performance result either from far more extensive video game experience or from pre-existing group differences in abilities that result in a self-selection effect.

The Recidivism Patterns of Previously Deported Aliens Released From a Local Jail: Are They High-Risk Offenders?

Previously deported aliens are a group about which numerous claims are made but very few facts are known. Using data on male deportable aliens released from a local jail, the study sought to test the ubiquitous claim that they pose a high risk of recidivism. Using multiple measures of recidivism and propensity score weighting to account for preexisting group differences, the authors find consistent support for the assertion that previously deported aliens are a high recidivism risk. Relative to similarly situated deportable aliens with no record of deportation, previously deported aliens are more likely to be rearrested, to be rearrested more quickly, and to be rearrested more frequently in a 1-year follow-up period.

Regression to the mean in substance use disorder treatment research

Regression to the mean (RTM) refers to the tendency for a group of cases that differ from the population mean to move (regress) towards the mean, on average, when re-assessed, if scores at the two points are less than perfectly correlated. This paper considers factors that affect the magnitude of RTM and how RTM may impact findings from primary studies and reviews of substance use disorder (SUD) treatment. The paper is guided largely by A Primer on Regression Artifacts by Campbell and Kenny. It reviews potential RTM effects in three areas of SUD treatment research. One is the extent to which within-group improvement in comparative treatment trials, including 'placebo effects', is a function of RTM. The second is the vulnerability of treatment evaluations employing non-equivalent control group designs to RTM and biased estimates of treatment effects when matching, or statistical equating is used to adjust for pre-existing group differences. The final issue is the impact of RTM in syntheses of research findings on SUD treatments. In particular, the tendency for later studies of a particular intervention to have smaller treatment effect sizes relative to earlier studies is considered as an RTM phenomenon. RTM is a pervasive, but often unrecognized phenomenon that can bias findings in SUD treatment studies and in systematic reviews of that research. SUD treatment researchers should be aware of RTM, take any available steps to reduce it, and try to diagnose whether it is still affecting research findings.

Mental Practice in Chronic Stroke

Mental practice (MP) of a particular motor skill has repeatedly been shown to activate the same musculature and neural areas as physical practice of the skill. Pilot study results suggest that a rehabilitation program incorporating MP of valued motor skills in chronic stroke patients provides sufficient repetitive practice to increase affected arm use and function. This Phase 2 study compared efficacy of a rehabilitation program incorporating MP of specific arm movements to a placebo condition using randomized controlled methods and an appropriate sample size. Method- Thirty-two chronic stroke patients (mean=3.6 years) with moderate motor deficits received 30-minute therapy sessions occurring 2 days/week for 6 weeks, and emphasizing activities of daily living. Subjects randomly assigned to the experimental condition also received 30-minute MP sessions provided directly after therapy requiring daily MP of the activities of daily living; subjects assigned to the control group received the same amount of therapist interaction as the experimental group, and a sham intervention directly after therapy, consisting of relaxation. Outcomes were evaluated by a blinded rater using the Action Research Arm test and the upper extremity section of the Fugl-Meyer Assessment. No pre-existing group differences were found on any demographic variable or movement scale. Subjects receiving MP showed significant reductions in affected arm impairment and significant increases in daily arm function (both at the P<0.0001 level). Only patients in the group receiving MP exhibited new ability to perform valued activities. The results support the efficacy of programs incorporating mental practice for rehabilitating affected arm motor function in patients with chronic stroke. These changes are clinically significant.