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PubMed1980

Methodological problems in the use of participant observers.

A multiple baseline design across observed students and teachers was used to investigate the relationship between observations by participant observers and changes in the behavior of those observed ("observee" reactivity) and the observers (observer-mediator reactivity). Two teachers recorded consecutively the appropriate student verbalizations of four students and two teachers recorded the inappropriate student verbalizations of four students. Independent observers simultaneously recorded student verbalizations (appropriate and inappropriate) as well as teacher behaviors (positive, negative, and instruction) throughout all phases of the study. The results substantiated the prediction of "observee" reactivity and observer-mediator reactivity in one of four classrooms. The results of the present study suggest that in some instances, observations by participant observers may result in changes in the behavior of those being observed ("observee" reactivity) and/or the observers (observer-mediator reactivity).

Journal Article↗

PubMed2000

Observer variability of lung function measurements in 2-6-yr-old children.

The aim of this study was to assess the within-observer and between-observer variability of lung function measurements in children aged 2-6 yrs. Two observers examined 22 asthmatic children independently according to a predefined protocol. Each observer obtained duplicate measurements of respiratory resistance by the interrupter technique (Rint), respiratory resistance (Rrs,5) and reactance (Xrs,5) at 5 Hz by the impulse oscillation technique and the specific airway resistance (sRaw) by whole body plethysmography. The within-subject SD (SDw) was not significantly different in the two observers. The ratio SDw between observers/mean SDw within observers was 0.94, 1.25, 1.35 and 2.86 for Xrs,5, Rrs,5, sRaw and Rint, respectively, indicating greater between-observer variability of the latter. The systematic difference between observers assessed by the difference between observer means (expressed as a percentage of their mean value) was 11, 7, 6 and 2% for Xrs,5, sRaw, Rrs,5 and Rint, respectively. These differences were statistically significant, except that for Rint. In conclusion, specific airway resistance, impulse oscillation technique and respiratory resistance assessed by the interrupter technique measurements in young children are subject to influence by the observer, and the random variability between observers appears to be particularly great for respiratory resistance assessed by the interrupter technique. The authors suggest that the between-observer variability should be investigated when evaluating novel methods for testing lung function.

Airway Resistance↗

PubMed2000

Representation of actions in rats: the role of cerebellum in learning spatial performances by observation.

Experimental evidence demonstrates that cerebellar networks are involved in spatial learning, controlling the acquisition of exploration strategies without blocking motor execution of the task. Action learning by observation has been considered somehow related to motor physiology, because it provides a way of learning performances that is almost as effective as the actual execution of actions. Neuroimaging studies demonstrate that observation of movements performed by others, imagination of actions, and actual execution of motor performances share common neural substrates and that the cerebellum is among these shared areas. The present paper analyzes the effects of observation in learning a spatial task, focusing on the cerebellar role in learning a spatial ability through observation. We allowed normal rats to observe 200 Morris water maze trials performed by companion rats. After this observation training, "observer" rats underwent a hemicerebellectomy and then were tested in the Morris water maze. In spite of the cerebellar lesion, they displayed no spatial defects, exhibiting exploration abilities comparable to controls. When the cerebellar lesion preceded observation training, a complete lack of spatial observational learning was observed. Thus, as demonstrated already for the acquisition of spatial procedures through actual execution, cerebellar circuits appear to play a key role in the acquisition of spatial procedures also through observation. In conclusion, the present results provide strong support for a common neural basis in the observation of actions that are to be reproduced as well as in the actual production of the same actions.

Animals↗

PubMed1993

Direct observation of driving, self reports of driver behaviour, and accident involvement.

Forty-eight drivers answered a set of written questions about their driving style and drove a pre-defined, mixed urban and motorway route under observation. For 20 drivers there was a second observer in the car to check on inter-observer reliability. Relationships were examined between self-reports of driver behaviour and observers' reports, and between both of these and the number of accidents in which the drivers had been involved in the past three years. The results indicated that there was good inter-observer agreement on a number of important variables including speed, calmness, and attentiveness. Inter-observer reliability for other variables was less good; among these were preferred distance to car in front, use of indicators, and aggressiveness. Observers also showed good agreement on overall ratings of driver skill and safety. Observed speed on the motorway correlated well with drivers' self reports of normal driving speed. Observer ratings of calmness correlated significantly with self-reports of calmness. Also observer ratings of attentiveness and carefulness correlated significantly with self-reports of deviant driving behaviour. Observed speed on the motorway showed a clear positive correlation with self-reported accident involvement. The results indicate that self-reports of certain aspects of driver behaviour can be used as surrogates for observational measures, thus providing a convenient extension to the researcher's methodological armoury. One such aspect is speed which appears to play an important role in accident involvement.

Accidents, Traffic↗

PubMed1995

Intra- and inter-observer agreement of brain MRI lesion volume measurements in multiple sclerosis. A comparison of techniques.

The measurement of MRI lesion load in multiple sclerosis is increasingly being used to evaluate the natural history of the disease and to monitor the efficacy of treatments. If, as might occur in multicentre studies, lesion load is measured by several observers in different patients or by the same observer in serial scans, it would be necessary to utilize a technique which provides results with high inter- and intra-observer agreements. This study was performed to evaluate the intra- and inter-observer agreement of semi-automated lesion volume measurement using thresholding, and to compare them with those obtained using an arbitrary scoring system (ASS) and a quantitative manual tracing method (MTM). Brain MRIs were obtained for 20 clinically definite multiple sclerosis patients and were evaluated independently by three observers. The median intra- and inter-observer agreements were, respectively, 88.5% (range 69.0-96.8%) and 79.0% (range 73.3-98.3%) using the ASS, 95.0% (range 85.1-99.4%) and 93.4% (range 77.3-98.3%) for the MTM, 96.3% (range 94.2-98.9%) and 93.7% (range 83.8-98.3%) for the semi-automated technique. The intra- and inter-observer agreements for the semi-automated technique increased to 98.5% (range 96.3-99.8%) and 96.1% (range 90.5-98.6%) when a consensus in the choice of threshold for lesion segmentation was reached. The intra- and inter-observer agreements were significantly greater for the semi-automated method compared with both the arbitrary scoring and the MTMs. The intra-observer variability for the semi-automated technique was significantly lower (P < 0.0001) than the inter-observer variability obtained using the same technique. These data indicate that it is possible to obtain high intra- and inter-observer agreements using a semi-automatic thresholding technique to quantify lesion volumes in multiple sclerosis. The technique may prove useful in multicentre studies, in which a single observer is still preferable.

Brain↗

PubMed2000

Evaluation of seizure observation and documentation.

This study evaluated seizure documentation after participants observed videotaped seizures to determine how their background (educational level, employment position, years of experience, practice frequency, and familiarity with epilepsy and seizures) and attributes of the seizures themselves affected their skill. Observer variables did not show significant differences when mean seizure rating scores of 348 documented seizures for 58 participants were compared. Combinations of variables were significant; certified nursing assistants (CNAs) with clinical seizure experience had significantly higher mean seizure rating scores than those without experience (p < .01). There were significant differences in the mean percentile scores for each seizure observed (p < .001). Seizures with excess motor activity had the highest scores. Most common observations for any seizure observed were location and description of movement. Participants had significantly higher scores when observing a seizure a second time (p < .001). Differences in education, employment position, and years of employment are not limiting factors in performing seizure observation and documentation for persons who have been trained and certified in the skill. Opportunities to periodically view seizures improved seizure observation and documentation. Because motor movement observations predominate seizure documents, seizure observation instruction should not only emphasize key observational details but also highlight less frequent observations, such as responsiveness, that may play a key role in seizure classification. Using videotaped seizures and a scoring tool are useful for initial training and certification as well as periodic retraining to maintain quality in the skill.

Child↗

PubMedDate not supplied

Inter-observer agreement of the physician's global assessment of disease activity in children with juvenile idiopathic arthritis.

OBJECTIVE: To assess the inter-observer agreement in the physician's global assessment of overall disease activity (MD global) in a cohort of patients with juvenile idiopathic arthritis (JIA). METHODS: Forty consecutive patients with JIA, who were representative of a wide spectrum of disease activity and severity, were examined simultaneously by 4 observers. Observer 1 (who was the most experienced rheumatologist) carried out a routine rheumatologic examination of each patient including a complete articular assessment, and subsequently calculated in secrecy the MD global score on an anchored horizontal 10-cm VAS. Observers 2, 3 and 4 were present during the examination; afterwards they also scored in secrecy the MD global score for the patient. Agreement was measured by the intra-class correlation coefficient (ICC), using the score of Observer 1 as the gold standard. An ICC below 0.75 was considered unsatisfactory. RESULTS: The mean (SD) MD global scores for Observers 1, 2, 3, and 4 were 5.2 (3.4), 6.7 (3.9), 5.9 (3.5), and 5.6 (3.7), respectively. The level of agreement with Observer 1 in scoring was 0.83 for Observer 2, 0.88 for Observer 3, and 0.90 for Observer 4, indicating good agreement for all observers. CONCLUSIONS: Our study shows a good inter-observer agreement in the physician's global assessment of overall disease activity in patients with JIA. Analyses involving investigators from different countries are needed to determine whether these results can be generalized.

Adolescent↗

PubMed1991

[Observer variation in clinical practice. A review].

Observer variation denotes the discrepancy between two consecutive observations of the same indicant. Principles and results of observer variation studies are outlined. Observer variation seems to be present wherever it is searched for, in history taking as well as in physical examination. It has been found unanimously to be smaller for intra- than for inter- observer variation while it is still controversial whether clinical experience lessens observer variation. Even fundamental clinical observations and particularly evaluations of borderline cases between normal and abnormal exhibit observer variation. The possibilities of reducing observer variation, and the importance of observer variation to clinicians and patients, and also the influence on research and society are referred to briefly. The future role of observer variation studies is discussed. Observer variation often is evaluated by the Kappa statistics whose statistical advantages and clinical disadvantages are outlined.

Observer Variation↗

PubMed1994

Inter- and intra-observer variation in the amniotic fluid index.

OBJECTIVE: To measure inter- and intra-observer reliability in the amniotic fluid index (AFI). METHODS: To measure inter-observer reliability, three observers measured the AFI at random in 32 patients without knowing each other's results. To determine intra-observer reliability, each investigator made repeated measurements on ten other patients. Patients at 26-41 weeks' gestation who were referred for an antenatal ultrasound examination were asked to participate. Intra-observer reliability and inter-observer reliability were expressed as intra-class correlation coefficients. Inter-observer agreement was also expressed as the kappa statistic after dichotomizing the AFI (less than 8 cm, 8 cm or more). RESULTS: The intra-class correlation coefficient for intra-observer reliability exceeded 0.8, and for inter-observer reliability it was 0.67 (95% confidence interval [CI] 0.52-0.79), with an overall kappa of 0.44 (95% CI 0.22-0.65). The percentage disagreement between pairs of observers reached 22-28%. CONCLUSION: Measurements of AFI have good intra-observer and moderate inter-observer agreement. In clinical use, an AFI level near a cutoff value should be interpreted with caution.

Amniotic Fluid↗

PubMed1996

Using mothers versus trained observers in assessing children's secure base behavior: theoretical and methodological considerations.

The Attachment Q-Set (AQS) has emerged as a psychometrically sound method for assessing young children's secure base behavior in the home. However, considerable disagreement exists about whether mothers versus trained observers should be used as AQS sorters. The present study examined associations between mothers' and trained observers' AQS sorts for preschoolers, and assessed mother-observer concordance in relation to observers' confidence about how representative the behavioral samples they witnessed were of the domain of AQS items. Mothers with careful training and supervision on the AQS system completed AQS sorts with regard to their children's current behavior, and the same children were assessed with the AQS during a 2-3 hour visit 1-2 weeks later by trained, "blind" observers. Trained observers provided a confidence rating regarding the degree to which the samples of behavior observed were representative of the universe of AQS items. Mothers' and observers' sorts were significantly intercorrelated; however, observer sorts converged with mother sorts as observers' confidence ratings increased. Results are discussed in relation to circumstances that affect mother-observer reliability with the AQS and to factors that should be weighed when considering whether to use mothers versus trained observers as sorters.

Adult↗

PubMed2003

Stimuli produced by observing responses make rats' ethanol self-administration more resistant to price increases.

RATIONALE: Observing responses bring sensory receptors into contact with environmental stimuli. In the observing-response procedure, periods in which an operant response (e.g. pressing a lever) is reinforced by drug deliveries alternate with periods in which this response is never reinforced (i.e. extinction). These alternating periods of drug availability versus extinction are not signaled. Observing responses (i.e. presses on a second lever) produce brief stimuli signaling whether drug is available or not for responses on the first lever. Little is known about how parameters of the drug reinforcer affect drug-stimulus observing. OBJECTIVES: The effects of changes in the unit price (responses/reinforcer magnitude) of self-administered ethanol on rats' observing were examined. Also, the effects of an observing-response-produced ethanol stimulus on ethanol consumption were examined by comparing consumption during signaled and unsignaled periods of ethanol availability. METHODS: Rats self-administered oral ethanol in the observing-response procedure. The unit price of ethanol in the observing-response procedure was increased by increasing the response requirement for ethanol across conditions. RESULTS: Observing and response rates on the ethanol lever increased and then decreased with increases in the unit price of ethanol. However, ethanol-lever responding and ethanol consumption during periods when ethanol was available were less sensitive to increases in price when the observing-response-produced ethanol stimulus was present. CONCLUSIONS: Observing varies as an orderly function of unit price of a drug reinforcer, and drug stimuli produced by observing responses can make drug consumption less sensitive to increases in price. This procedure may provide an animal model of both attending to drug stimuli and the resultant effects of these stimuli on drug taking.

Animals↗

PubMed2005

Action observation supports effector-dependent learning of finger movement sequences.

Practising a motor skill can result in effector-dependent learning (learning that does not transfer from the set of muscles used in training to a new set of muscles). Proceeding from neurophysiological evidence of motor activation during action observation, this study asked whether observational learning, learning through observation of skilled performance, can also be effector-dependent. Adult human participants observed a model's right hand as the model responded to an eight-item sequence in a serial reaction time (SRT) task. Their sequence learning was then compared in two tests with that of controls who had observed the model's right hand responding to random targets during training. All participants performed the SRT task with their right hand in the first test and with their left hand in the second. Evidence of observational learning was obtained in the right hand test but not in the left hand test. This implies that sequence learning based on observation of right hand performance did not transfer to the left hand, and therefore that observational learning can support effector-dependent learning of finger movement sequences. A second experiment used the same procedure to assess learning by a group of participants who observed a sequence of response locations only. This group did not observe the model's responses. Results suggested that action observation was necessary for the effector-dependent observational learning demonstrated in Experiment 1.

Adult↗

PubMed1999

Stereothresholds in persons wtih congenital nystagmus and in normal observers during comparable retinal image motion.

Despite rapid oscillations of the eyes, visual acuity is close to normal in many observers with congenital nystagmus (CN). This study investigated whether binocular hyperacuity thresholds are also close to normal in observers with CN. To do so, we assessed stereothresholds for horizontally and vertically separated line targets in three normal observers and six observers with idiopathic horizontal CN. Stereothresholds in normal observers are better than in the observers with CN, especially for horizontally-separated targets and very small inter-line separations. Stereothresholds remain better in normal observers than in the observers with CN, even in the presence of conjugate retinal image motion simulating that in jerk nystagmus. However, when the simulated CN wave form also includes disconjugate position variability of the foveation periods, normal observers' stereothresholds become similar to those of approximately half of the observers with CN. We conclude that stereothresholds in observers with CN are degraded by the more-or-less constant motion of the retinal image, by excessive vergence instability and, in some observers, by a neural sensory deficit.

Depth Perception↗

PubMed1996

Elective neck irradiation versus observation of the clinically negative neck of patients with oral cancer.

PURPOSES: A retrospective study was conducted to determine the efficacy of elective neck irradiation (ENI) versus observation of patients with oral tumors of varying T stages and clinically negative necks, and to statistically evaluate outcome in the two groups with regard to the subsequent development of neck disease. PATIENTS AND METHODS: Seventy-three patients were treated with surgery of their primary site; 31 received ENI, and 42 of the necks were observed. Of the ENI patients, 3.2% developed neck disease compared with 31% of those observed. When the two groups were evaluated by the T stage of the primary tumor, the results for ENI versus observation were as follows: T1 (0% vs 31%), T2 (5.9% vs 26.7%), T3 + 4 (0% vs 31%), respectively (P < .0000, adjusted odds ratio = 13.73, 95% confidence interval). The difference between the two groups was highly statistically significant. One hundred fourteen patients were treated with only radiation therapy alone at the primary site. In this group, 88 received ENI, and 16 necks were observed. Eight percent of the ENI group developed neck disease, compared with 3.8% of the observational group. Further evaluation by T stage of ENI versus observation showed T1 (3% vs 0%); T2 (9.3% vs 7.7%); T3 + 4 (5.6% vs 0%), respectively. The difference between these groups was not found to be statistically significant. RESULTS: The 5-year disease-free survival rate for the surgical group was 90% for patients who received ENI and 40% for those observed. This difference was statistically significant (P = .0007). No statistical difference was found in 5-year disease-free survival for the radiation group between ENI and observation. CONCLUSIONS: When comparing the above data for ENI versus observation, the survival advantages of elective neck irradiation in patients whose primary tumor was treated surgically is striking for all T stages. These results make the decision to observe the neck in such patients difficult to justify. Lack of statistical difference between ENI and observation in the radiation cohort likely reflects selection bias. If radiation therapy is being used to treat the primary disease, only low-risk sites or histologically favorable tumors would not, on a routine basis, have the neck fields treated as well.

Adult↗

PubMed1975

Witnessed aggression: influence of an observer's sex and values on aggressive responding.

Two experiments investigated the effects of the presence of an observer on aggressive responding. In one experiment, male subjects observed by a male aggressed more than those observed by a female. When the male observer was removed from the situation, subjects' level of aggressiveness more closely matched the level manifested by the opponent. The removal of the female observer had little effect on the subjects' behavior. In the second experiment, the male or female observer of the subject's behavior was disguised as a member of an organization with explicit values (aggressive or pacifistic) regarding the use of aggression. In this case, significant differences in aggression were associated with the observer's values but not the observer's sex. Following the departure of the observer, the shock settings of subjects in the two aggressive-value observer groups showed a signifcant decrease. The average shock setting of subjects in the two pacifistic-value observer groups remained at about the same level. In sum, the results indicated that the subjects' aggressive behavior was apparently a function of their expectations of approval for such behavior, based on the inferred or explicit values of the observer. The results were further discussed in terms of social learning theory.

Aggression↗

PubMed2006

Intention in motor learning through observation.

The purpose of this experiment was to assess whether learning an action through observation is enhanced by the intention to reproduce the observed behaviour. Two groups of participants observed a model practise a timing task and performed a 24-hour delayed retention test. Participants in the first group of observers were explicitly instructed that they would be required to execute the timing task that they had observed as accurately as possible during the delayed retention test. Observers in the second group were instructed that they would be required to describe as accurately as possible the behaviour that they had observed. A control group of participants, who did not observe the model, was also administered the delayed retention test. The results of the retention test indicated that absolute timing (parameterization) was learned by the observers to the same extent with or without intention to reproduce the task. Indeed, on the retention test absolute timing for the two groups of observers was as effective as that for the models. However, observing with an intention to reproduce the task was beneficial for learning the movement's relative timing structure. Results are discussed with respect to a potential mechanism by which intention enhances observation.

Adolescent↗

PubMed2000

Triage of patients for short term observation after elective coronary angioplasty.

OBJECTIVE: To evaluate triage of patients for short term observation after elective percutaneous transluminal coronary angioplasty (PTCA), as appropriate selection of patients for short term observation after angioplasty may facilitate early discharge. METHODS: 1015 consecutive patients scheduled for elective PTCA were prospectively included for short term observation. Patients with unstable angina Braunwald class III were excluded. There were no angiographic exclusion criteria. Patients were discharged from the interventional centre when considered stable during 4 hours of observation after PTCA. It was left to the operator's discretion whether to prolong the observation period. Procedural complications were defined as death, coronary bypass surgery, early repeat PTCA, and myocardial infarction. OUTCOME MEASURES: The need for prolonged observation (> 4 hours) and the occurrence of complications. Predictors for prolonged observation and the occurrence of complications after the 4 hours observation were assessed by univariate and multivariate analysis. RESULTS: Two patients died, including one of six patients who underwent emergency bypass surgery. In all, 922 patients (90.8%) were triaged to short term observation and had an uncomplicated three day follow up. Observation was prolonged in 87 patients (8.6%), and 40 patients had a complicated course. Independent predictors of procedural complications were acute closure (odds ratio (OR) 9.7; 95% confidence interval 4.4 to 21.4), side branch occlusion (OR 8.9; 3.4 to 23.7), no angiographic success (OR 5.1; 2.4 to 11.0), female sex (OR 3.1, 1.7 to 5.7), any unplanned stent (OR 2.8, 1.4 to 5.9), and ostial lesion (OR 2.2, 1.0 to 4.7). CONCLUSIONS: A 4 hour observation period is safe after elective coronary angioplasty. As procedural variables are the strongest predictors of postprocedural complications, the immediate procedural results allow effective triage of patients for short term or prolonged observation in order to anticipate complications.

Adult↗

PubMed2005

Efficiency of the human observer detecting random signals in random backgrounds.

The efficiencies of the human observer and the channelized-Hotelling observer relative to the ideal observer for signal-detection tasks are discussed. Both signal-known-exactly (SKE) tasks and signal-known-statistically (SKS) tasks are considered. Signal location is uncertain for the SKS tasks, and lumpy backgrounds are used for background uncertainty in both cases. Markov chain Monte Carlo methods are employed to determine ideal-observer performance on the detection tasks. Psychophysical studies are conducted to compute human-observer performance on the same tasks. Efficiency is computed as the squared ratio of the detectabilities of the observer of interest to the ideal observer. Human efficiencies are approximately 2.1% and 24%, respectively, for the SKE and SKS tasks. The results imply that human observers are not affected as much as the ideal observer by signal-location uncertainty even though the ideal observer outperforms the human observer for both tasks. Three different simplified pinhole imaging systems are simulated, and the humans and the model observers rank the systems in the same order for both the SKE and the SKS tasks.

Algorithms↗