Baseline Level Of Performance Research Articles

A Data-Centric Approach to Improve Machine Learning Model’s Performance in Production

Machine learning teaches computers to think in a similar way to how humans do. An ML models work by exploring data and identifying patterns with minimal human intervention. A supervised ML model learns by mapping an input to an output based on labeled examples of input-output (X, y) pairs. Moreover, an unsupervised ML model works by discovering patterns and information that was previously undetected from unlabelled data. As an ML project is an extensively iterative process, there is always a need to change the ML code/model and datasets. However, when an ML model achieves 70-75% of accuracy, then the code or algorithm most probably works fine. Nevertheless, in many cases, e.g., medical or spam detection models, 75% accuracy is too low to deploy in production. A medical model used in susceptible tasks such as detecting certain diseases must have an accuracy label of 98-99%. Furthermore, that is a big challenge to achieve. In that scenario, we may have a good working model, so a model-centric approach may not help much achieve the desired accuracy threshold. However, improving the dataset will improve the overall performance of the model. Improving the dataset does not always require bringing more and more data into the dataset. Improving the quality of the data by establishing a reasonable baseline level of performance, labeler consistency, error analysis, and performance auditing will thoroughly improve the model's accuracy. This review paper focuses on the data-centric approach to improve the performance of a production machine learning model.

Measuring global functioning in older adults with cognitive impairments using the Rasch model

BackgroundCognitive and functional measures are often measured and interpreted separately during the clinical evaluation of patients with cognitive impairment. This can sometimes lead to a challenging interpretation when measures do not show concordance, especially after a clinical intervention. In this study, the development and evaluation of a new approach, using the Rasch model, that combines cognitive and functional measures in one single and more powerful measure (compared to stand-alone tests) to assess global functioning in older adults with cognitive impairment (including dementia) was presented.MethodsClinical data from 265 older adults’ subjects diagnosed with mild cognitive impairment, or dementia, included: The Mini-mental state examination (MMSE), the Esame Neuropsicologico Breve (ENB) – a neuropsychological battery used in Italy–, the Activities of Daily Living (ADL), and the Instrumental Activities of Daily Living (IADL) questionnaires.ResultsPatients with severe cognitive impairment showed lower global functioning score compared to patients with moderate impairment. Receiver Operating Characteristic (ROC) curve analyses were performed to determine sensitivity and specificity of the global functioning score resulting from the combined measure. Results showed that the global functioning score discriminates better between patients with severe and moderate cognitive impairment compared to the ENB, ADL, and IADL when considered separately.ConclusionsThe Rasch model was able to combine cognitive and functional measures into a single score (global functioning score). All together, these results suggest that the diverse cognitive and functional measures can be considered part of one single dimension (global functioning) and that this dimension can be measured as a single construct and score. This study offers an alternative perspective for future development of instruments that would help clinicians in measuring global functioning in older adults’ patients at different stages of cognitive impairments and different baseline level of performance.

Using performance-based warranties to influence consumer purchase decisions

Traditional warranty analysis focuses on the reliability of a product and offers warranty designs that compensate a consumer if the item fails. We introduce the concept of a performance-based warranty (PBW) that guarantees that a product will operate at or above some baseline level of performance, such as a minimum energy efficiency for an appliance. We illustrate how consumer behavior can change in the presence of a PBW and define the parameters for which a manufacturer may increase revenue. Finally, we present an algorithm to solve for the optimal PBW design given a consumer’s belief about the expected performance of the product.

Effect of Concussion on Performance of National Football League Players.

Lingering neurologic injury after concussion may expose athletes to increased risk if return to play is premature. The authors explored whether on-field performance after concussion is a marker of lingering neurologic injury. Retrospective cohort study on 1882 skill-position players who played in the National Football League (NFL) during 2007-2010. Players with concussion based on the weekly injury report were compared with players with other head and neck injuries (controls) on measures of on-field performance using Football Outsiders' calculation of defense-adjusted yards above replacement (DYAR), a measure of a player's contribution controlling for game context. Changes in performance, relative to a player's baseline level of performance, were estimated before and after injury using fixed-effects models. The study included 140 concussed players and 57 controls. Players with concussion performed no better or worse than their baseline on return to play. However, a decline in DYAR relative to their prior performance was noted 2 wk and 1 wk before appearing on the injury report. Concussed players performed slightly better than controls in situations where they returned to play the same week as appearing on the injury report. On return, concussed NFL players performed at their baseline level of performance, suggesting that players have recovered from concussion. Decline in performance noted 2 wk and 1 wk before appearing on the injury report may suggest that concussion diagnosis was delayed or that concussion can be a multihit phenomenon. Athletic performance may be a novel tool for assessing concussion injury and recovery.

Differentiation of rodent behavioral phenotypes and methylphenidate action in sustained and flexible attention tasks

Methyphenidate (MPH) is the primary drug treatment of choice for ADHD. It is also frequently used off-label as a cognitive enhancer by otherwise healthy individuals from all age groups and walks of life. Military personnel, students, and health professionals use MPH illicitly to increase attention and improve workplace performance over extended periods of work activity. Despite the frequency of its use, the efficacy of MPH to enhance cognitive function across individuals and in a variety of circumstances is not well characterized. We sought to better understand MPH׳s cognitive enhancing properties in two different rodent models of attention. We found that MPH could enhance performance in a sustained attention task, but that its effects in this test were subject dependent. More specifically, MPH increased attention in low baseline performing rats but had little to no effect on high performing rats. MPH exerted a similar subject specific effect in a test of flexible attention, i.e. the attention set shifting task. In this test MPH increased behavioral flexibility in animals with poor flexibility but impaired performance in more flexible animals. Overall, our results indicate that the effects of MPH are subject-specific and depend on the baseline level of performance. Furthermore, good performance in in the sustained attention task was correlated with good performance in the flexible attention task; i.e. animals with better vigilance exhibited greater behavioral flexibility. The findings are discussed in terms of potential neurobiological substrates, in particular noradrenergic mechanisms, that might underlie subject specific performance and subject specific responses to MPH.This article is part of a Special Issue entitled SI: Noradrenergic System.

What is a normal change in memory? n=1 classification of clinically relevant cognitive decline

Background: Clinicians often have to decide whether a person’s reported or measured change in cognition reflects normal aging or clinically-relevant cognitive decline. For most cognitive tests, there is no evidence-based guidance for how much change is ‘normal’ over a given timeframe. This study aimed to statistically determine the limits of clinically-significant memory change among healthy older adults and those with mild cognitive impairment (MCI). Methods: Longitudinal cognitive performance was examined in 21 healthy older adults and 81 individuals with clinically-defined MCI. Participants were assessed on Cantab Paired Associate Learning (PAL), a non-verbal episodic memory test, at baseline, 10 months and 20 months as part of a comprehensive neuropsychological assessment. They were classified as amnestic-MCI if there was a deficit (performance <10th percentile relative to norms) in memory tests (with our without impairment in other cognitive tests), and nonamnestic MCI if deficits were limited to non-memory domains. Over the three assessments, MCI was stable, resolved or progressed to dementia. The performance of control participants was used to determine the normal limits for initial and longitudinal change in performance, against which participants with stable or resolved MCI and those who progressed to dementia could be compared on an individual basis. Results: In healthy controls, PAL showed good stability using Bland-Altmann analysis. Na-MCI, and those with resolved MCI performed at a level comparable to healthy controls on each occasion. Patients with stable a-MCI or AD patients were significantly impaired relative to other groups. This persisted even when controlling for age, education, gender and baseline level of performance. Individual estimates of clinically significant impairment and change were able to reliably detect patients who would subsequently develop dementia, or had stable a-MCI. Conclusions: Repeated assessments with the Cantab PAL test are feasible, show good psychometric properties, and can characterise typical and atypical patterns of change in episodic memory. A repeat assessment of memory at <1 year can reliably inform clinical decisions about the presence or absence of pathological cognitive decline.

A Steady-State Contingency Analysis of the SADC Regional Grid Using the N-1 Criterion

Southern Africa has experienced electric power deficits over the last decade. This has been due in part to the member countries' inadequate electrical power supply system, as well as load growth in areas which were not adequately planned for. This has induced the formation of organizations such as SADC (Southern African Development Community) and SAPP (Southern African Power Pool) that have the common goal of achieving development and economic growth in the region which comprises of 15 member countries. This paper presents results from a security analysis of the region's electric power supply system using a baseline level of performance. This was carried out by performing a steady-state contingency analysis on a SADC power network model subject to the N-1 criteria which expresses the ability of the power network to experience a contingency without causing an overload or failure in any other part of the network. Simulations were carried out using DigSilent.

A Simulation Study to Assess a Variable Selection Method for Selecting Single Nucleotide Polymorphisms Associated with Disease

In genome-wide association studies, where hundreds of thousands of single nucleotide polymorphisms (SNPs) are genotyped, the potential for false positives is high and methods for selecting models with only a few SNPs are required. Methods for variable selection giving sets of SNPs associated with disease have been developed, but are still less common than evaluation of individual SNPs one at a time. To assess the potential improvement available from multi-SNP approaches, we examined the performance of the software GeneRaVE as a variable selection method when applied to SNP data in case-control studies. The method was assessed via simulations, in which a haplotype identified by three SNPs was taken to be associated with the disease. Simulated data sets reflecting different levels and patterns of genetic association with the disease were generated. In order to have a baseline level of performance to assess the method against, we used a generalized linear model using only the three disease susceptibility SNPs to provide an upper bound on the possible performance of the selection methods. To investigate the advantage of using variable selection method as a multivariate method over a single SNP approach, we used chi-squared tests for each of the disease susceptibility (DS) SNPs with correction for multiple testing. Simulation results showed that GeneRaVE performed well and outperformed single SNP analysis using the chi-squared method in identifying disease-related SNPs. In application to a large dataset, it identified SNPs known to be associated with disease that were not identified by single SNP methods.

Outcomes among older people in a post-acute inpatient rehabilitation unit

Purpose: Designated multidisciplinary rehabilitation units have been shown to provide several benefits for the frail older population. The aim of this research was to evaluate changes in strength, mobility, balance, endurance, frailty and quality of life (QoL) following a 6-week multidisciplinary inpatient rehabilitation programme. Method: This was a prospective, observational study performed in a post-acute multidisciplinary geriatric inpatient rehabilitation service. A consecutive sample of heterogenous frail older adults (n = 32) participated. Subjects were assessed on admission to the rehabilitation service (T1) and following 6 weeks of rehabilitation (T2). A range of outcome measures were used to assess function and QoL: Berg Balance Scale (BBS), Timed Up and Go (TUG), 6-Minute Walk Test (6MWT), Barthel Index (BI), EuroQol-Visual Analogue Scale (EQ-VAS), Clinical Frailty Scale (CFS), lower limb and grip dynamometry. Results: The majority were female (n = 25), the mean age was 82.9 years (SD 6.35). The median length of stay was 49 days. Patients improved significantly between T1 and T2 assessments in the BBS (p ≤ 0.0001); TUG (p ≤ 0.0001); 6MWT (p ≤ 0.0001); BI (p ≤ 0.0001); EQ-VAS (p = 0.002); CFS (p ≤ 0.0001); and in some aspects of grip and lower limb strength. Conclusion: This study has demonstrated that positive outcomes occurred in a range of measures in an older, frail inpatient rehabilitation population.Implications for RehabilitationElderly inpatients undergoing rehabilitation programmes improve across a range of measures looking at impairment, activity, participation and quality of life.However, gains were modest and patients did not attain their baseline level of performance after a 6-week programme of inpatient rehabilitation.Using outcome measures in clinical rehabilitation practice can facilitate comparison between units and can form the basis for future research in this population.

The Medial Temporal Lobe Supports Conceptual Implicit Memory

The medial temporal lobe (MTL) is generally thought to be critical for explicit, but not implicit, memory. Here, we demonstrate that the perirhinal cortex (PRc), within the MTL, plays a role in conceptually-driven implicit memory. Amnesic patients with MTL lesions that converged on the left PRc exhibited deficits on two conceptual implicit tasks (i.e., exemplar generation and semantic decision). A separate functional magnetic resonance imaging (fMRI) study in healthy subjects indicated that PRc activation during encoding of words was predictive of subsequent exemplar generation. Moreover, across subjects, the magnitude of the fMRI and behavioral conceptual priming effects were directly related. Additionally, the PRc region implicated in the fMRI study was the same region of maximal lesion overlap in the patients with impaired conceptual priming. These patient and imaging results converge to suggest that the PRc plays a critical role in conceptual implicit memory, and possibly conceptual processing in general.

Acetylcholinesterase inhibitors in Alzheimer's disease.

Alzheimer’s Disease (AD) is the most common single cause of dementia in our ageing society. Traditionally thought of as an untreatable degenerative condition, recent advances in drug therapy have challenged this view. The disease is characterised by an insidious decline in cognitive and non-cognitive function. Classically, short and long-term memory is impaired while language skills, concentration and attention are often affected. This results in impaired ability to learn and retain new skills as well as the loss of existing ones. Non-cognitive function is the global term used to describe problems such as depression, agitation, personality changes, delusions and hallucinations. These factors have a significant impact on patient behaviour and a very real impact on the quality of life for both patients and caregivers. Diagnosis of AD is clinically based, and using the NINCDS-ADRDA criteria (Table 1) [1], a diagnosis of probable or possible AD can be made. Definitive diagnosis relies on pathological confirmation, which in the majority of cases is rarely completed. With the development of AD specific treatments, definition of AD from other types of dementia is very important. Table 1 NINCDS-ADRDA Criteria for clinical diagnosis of Alzheimer’s disease. Pathogenesis The pathogenesis of AD has not yet been elucidated. It is widely accepted that a combination of genetic susceptibility factors and environmental triggers are responsible for late onset sporadic AD, the most common form of the disease. An understanding of the disease mechanism remains elusive, and is the key to developing a disease modifying agent. Currently, it is proposed that beta amyloid protein, abnormal tau protein or possibly both play key factors in the development of disease. It has been widely postulated that oxidative damage and a slow inflammatory process are two possible mechanisms involved. As yet, no product with proven disease modifying properties is available, and current treatments offer symptomatic benefit only. The development of acetylcholinesterase (AChe) inhibitor drugs has followed the finding that cholinergic pathways in the cerebral cortex and basal forebrain are compromised in AD [2] and the resultant cholinergic deficit contributes to the cognitive impairment of these patients [3]. Although many believe this ‘cholinergic hypothesis’ to be important, others feel it represents a less significant component of the disease process [4]. Many other neurotransmitters are affected in AD, and the relative importance of each in relation to clinical findings has not been fully elucidated. Initial work focused on the use of acetylcholine precursors, using a similar rationale to dopamine therapy in Parkinson’s disease. A series of small trials using precursors such as choline and phosphatidylcholine showed no reliable improvement in cognitive function, with only 10 out of 43 trials reporting any positive effect [5]. There has been renewed interest in muscarinic agonists drugs, which when first introduced, had major problems with adverse cholinergic effects. Better understanding of the molecular pathology of muscarinic receptors and their subtypes has led to the development of more specific agonists. Drugs such as xanomeline, milameline, and civimeline have reached clinical trials, and the improvements seen in cognitive function are reviewed by Avery et al. [6]. There are also claims that these drugs have disease modifying properties, with effects on APP processing and tau phosphorylation. Muscarinic agonists remain in trial, but have yet to fulfil their potential in AD treatment. The only group of drugs currently licensed for AD treatment is the AChe inhibitors, which act through inhibition of the enzyme acetylcholinesterase (AChe), responsible for the breakdown of ACh in the neural synapse. A meta-analysis of the early AChe inhibitor treatments was encouraging [7] and these proceeded to larger placebo controlled double-blind trials.

The determination of clinically meaningful cognitive decline: Development and use of an alternative method

Statistical methods traditionally used in the analysis of change (e.g., repeated measures ANOVA) may be inadequate for the investigation of cognitive decline if a study's effect size is small, the variance within groups is heterogeneous, or the statistical power is low. To examine an alternative approach to the determination of clinically meaningful cognitive decline and investigate whether such decline occurs during the first year after stroke, we administered a neuropsychological test battery to 172 patients (age= 70.3 ± 7.6years;education= 10.3 ± 4.7years) 3 and 12 months after stroke and 199 nondemented stroke-free control subjects (age= 71.1 ± 6.4years;education= 12.8 ± 4.2years) on two occasions 12 months apart. Two neuropsychologists classified each subject's test performance as having declined, improved, or remained stable based solely on clinical judgment. Reliability of the rating of decline versus the pooled rating of improvement/stability was excellent (kappa= 0.79). The two rating groups differed significantly and in the appropriate directions in change on most tests. While a MANOVA comparing the stroke and control groups on change in test scores was not significant, logistic regression analysis determined that a rating of clinically meaningful cognitive decline was associated with stroke status (Odds Ratio= 1.8, 95%Confidence Interval= 1.0to3.2), while adjusting for demographic factors. We propose that this alternative approach to the analysis of cognitive change can facilitate the recognition of decline in subgroups of subjects. It would be valuable as an adjunct to studies of the incidence of dementia, for example, in which the recognition of cognitive decline might be difficult in highly educated patients whose baseline level of performance is far above the cutoffs operationalized for the diagnosis of dementia.

The determination of clinically meaningful cognitive decline: Development and use of an alternative method

Statistical methods traditionally used in the analysis of change (e.g., repeated measures ANOVA) may be inadequate for the investigation of cognitive decline if a study's effect size is small, the variance within groups is heterogeneous, or the statistical power is low. To examine an alternative approach to the determination of clinically meaningful cognitive decline and investigate whether such decline occurs during the first year after stroke, we administered a neuropsychological test battery to 172 patients (age = 70.3 +/- 7.6 years; education = 10.3 +/- 4.7 years) 3 and 12 months after stroke and 199 nondemented stroke-free control subjects (age = 71.1 +/- 6.4 years; education = 12.8 +/- 4.2 years) on two occasions 12 months apart. Two neuropsychologists classified each subject's test performance as having declined, improved, or remained stable based solely on clinical judgment. Reliability of the rating of decline versus the pooled rating of improvement/stability was excellent (kappa = 0.79). The two rating groups differed significantly and in the appropriate directions in change on most tests. While a MANOVA comparing the stroke and control groups on change in test scores was not significant, logistic regression analysis determined that a rating of clinically meaningful cognitive decline was associated with stroke status (Odds Ratio = 1.8, 95% Confidence Interval = 1.0 to 3.2), while adjusting for demographic factors. We propose that this alternative approach to the analysis of cognitive change can facilitate the recognition of decline in subgroups of subjects. It would be valuable as an adjunct to studies of the incidence of dementia, for example, in which the recognition of cognitive decline might be difficult in highly educated patients whose baseline level of performance is far above the cutoffs operationalized for the diagnosis of dementia.

Spatial learning in two inbred strains of mice: genotype-dependent effect of amygdaloid and hippocampal lesions

Spatial learning performance and maze-running strategies were estimated in two inbred strains of mice, C57BL/6 and DBA/2, submitted to an 8-arm radial maze task. Subsequently the genotype-dependent effect of hippocampus and amygdala on the mastering of this task was examined as a function of the different acquisition model provided by each strain. The results firstly show that unoperated C57BL/6 mice reach a higher level of performance and develop a stronger preference for adjacent arms - 45 degrees angle - turns than unoperated DBA/2 mice. In the high learner C57BL/6 strain, both hippocampal and amygdaloid lesions impair performance and modify maze-running strategies. With practice, however, the difference between amygdala-lesioned mice and controls disappears while that between hippocampus-lesioned mice and controls persists. Conversely, in the low learner DBA/2 strain, hippocampal lesions have a negative effect on a single parameter of performance, while amygdaloid lesions only affect maze-running strategies. Taken together, these results confirm the specific control exerted by the hippocampus on spatial learning. Moreover, they suggest that the amygdala can parallel the role of the hippocampus as far as the baseline level of performance of the strain considered is high.

Visual recognition memory in squirrel monkeys: Effects of serotonin antagonists on baseline and hypoxia-induced performance deficits

Cognitive deficits resulting from neuropathological brain changes such as Alzheimer's Disease or normal aging are most likely due to alterations in multiple neurotransmitter systems. While the majority of preclinical studies have focused on the effects of acetylcholine (ACh), it has been shown that activation of the serotonergic (5-HT) pathways in the central nervous system interferes with passive avoidance retention in rats. In contrast, decreased 5-HT activity has been shown to improve learning and memory in rats using similar procedures. In the present experiment, 5-HT antagonists were evaluated for their effects on performance in a delayed match to sample task (DMTS) in two groups of squirrel monkeys: one in which the baseline level of performance was low (less than 65% correct, N = 5; group 1) and another in which DMTS performance was high (greater than 80% correct, N = 3; group 2) but impaired by exposure to hypoxia. Initial parametric tests exposing group 2 to various levels of oxygen deprivation were conducted to determine optimal conditions for performance deficits. Each monkey in both normoxia (group 1) and hypoxia (group 2) served as his own control and received an individualized range of doses for each test compound. For both groups, ketanserin and mianserin, the 5-HT2-selective antagonists, produced dose-dependent increases in DMTS performance at 0.3-1.5 mg/kg PO and 0.05-1.5 mg/kg PO, respectively. Pirenperone, another 5-HT2-selective antagonist, was active in improving performance in group 1 at 0.001 to 0.2 mg/kg PO but was not effective against hypoxia-induced performance deficits.(ABSTRACT TRUNCATED AT 250 WORDS)

Teaching the Wisconsin Card Sorting Test to Schizophrenic Patients

To the Editor.— We were impressed by the article of Goldberg et al 1 that appeared in the November 1987 issue of theArchives, in which the authors tried to teach schizophrenic patients how to perform on the Wisconsin Card Sorting Test. Typically, schizophrenic patients do very poorly on this test of frontal lobe functioning, even when compared with their performance on other cognitive measures. The patients were able to perform adequately when the experimenter gave detailed trial-by-trial instructions. Essentially, the experimenter acted as the patient's frontal lobe by giving these instructions. Interestingly, the patients returned to their baseline level of performance when instructions were withdrawn. The Goldberg et al study seems to suggest that the schizophrenic patients are unable to learn the Wisconsin Card Sorting Test. One problem with the study is that the behavioral contingencies for learning to take place were not optimal: sufficient reinforcement for the maintenance

Task Clarification and Individual Performance Posting for Improving Cleaning in a Student-Managed University Bar

A modified multiple baseline design across groups was employed to evaluate the effects of task clarification and individual performance posting procedures on low-probability cleaning behaviors for persons who worked in a wholly student-managed university bar. Products of cleaning behaviors were defined in terms of behavioral checklists, and were assessed by student managers who were reliably trained. Task clarification, introduced simultaneously to all groups, resulted in an abrupt 13% increase in checkmarks (maintained thereafter over a 5-week period) over those earned during the baseline level of performance. Introduction of performance posting for the first group produced an additional 37% increase in checkmarks that were reliably greater (ps < .05) than for the other two. Nonetheless, an apparent generalization of this posting effect (23% mean increase) occurred concomitantly for the subjects of two unposted groups. Increases in checkmarks to levels that were comparable to that of Group 1 occurred the...

Behavioral Treatments for Heterosocial Problems

Three group treatments for heterosocial problems (systematic desensitization, social skills training, structured homework with cognitive restructuring) were compared to an assessment-control condition. Extensive self-recording of naturally-occurring social interactions and roleplayed interactions in the laboratory provided data for the evaluation of treatment impact. Roleplay assessment of social behavior produced effects for repeated measurement but did not discriminate between treatment conditions. Analyses of covariance of daily self-monitoring data revealed treatment differences, but the covariate (baseline level of performance) was the largest source of variation. The importance of person variables or person-by-situation interactions is highlighted; suggestions for future research are discussed.

BEHAVIOR MODIFICATION WITH CULTURALLY DEPRIVED SCHOOL CHILDREN: TWO CASE STUDIES1

Techniques of behavior modification were employed with two second-grade Negro girls in a demonstration school for culturally deprived children to increase the girls' appropriate classroom behaviors. A classification system that provided for continuous categorization of behavior was used to code the children's behavior in two classroom situations. Data were also taken on the type, duration, and frequency of the teachers' verbal interactions. The study included four conditions: Baseline, Modification I, Postmodification, and Modification II. The treatment variable was positive social reinforcement-attention and approval contingent upon desirable classroom behaviors-which was presented, withheld, or withdrawn (timeout from social reinforcement). Withholding of social reinforcement was contingent upon inappropriate attention-getting behaviors. Timeout from social reinforcement was contingent upon behaviors classified as aggressive and resistive. After 25 days of Modification I, desirable behavior increased markedly for each girl. The teachers were then asked to return to their Baseline level of performance. The resultant behaviors demonstrated that for one girl, behavior was still primarily under the control of the treatment contingencies. For the second child, many desirable behaviors that had increased in frequency during Modification I remained high, but inappropriate behaviors increased. When treatment was reinstated, the amount of time spent in desirable behaviors increased and remained high for both girls. Three checks during the three months following data collection showed that these behaviors continued to remain high.

Effect of 2,5-Dimethyoxy-4-Methyl-Amphetamine (Dom) on Psychophysical Responding by a Chimpanzee

Specific interest in this study centered on the assessment of perceptual change in the chimpanzee, made possible by a new psychophysical apparatus. S was given single dosages of 5 and 10 mg DOM, separated by appropriate baseline measures. The 5-mg dosage produced a change in 3 of 7 performance variables while the 10-mg dosage produced a change in all 7. The effect of 5 mg DOM, when significant, lasted up to 2¾ hr. The effect of 10 mg DOM, when significant, lasted up to 8 hr. The peak effect of the compound occurred between 2½ and 3 hr. under both dosage levels, with S returning to a baseline level of performance within an 8-hr. experimental period. There were no post-experimental effects which could be attributed to the DOM.