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PubMed2003

The resistance to change of observing.

Observing responses produce contact with discriminative stimuli and have been considered analogous to attending. Many studies have examined the effects of reinforcement rate on the resistance to change of simple operant behavior, but nothing is known about the resistance to change of observing. Two experiments examined the effects of primary reinforcement rate on the resistance to change of observing behavior of pigeons. In Experiment 1, a multiple schedule of observing-response procedures was arranged. In a rich component, observing responses produced stimuli correlated with a high rate of random-interval (RI) reinforcement or extinction. In a lean component, observing responses produced stimuli correlated with a lower rate of RI reinforcement or extinction. In both components, observing responses produced the multiple-schedule stimuli on a fixed-interval 0.75-s schedule. In Experiment 2, a similar procedure was used, but observing in the rich and lean components produced schedule-correlated stimuli on an RI 15-s schedule. Observing in the rich component occurred at a higher rate and was more resistant to disruptions produced by presession feeding and response-independent food deliveries during intercomponent intervals. Despite more frequent observing during unsignaled periods of extinction than unsignaled periods of RI reinforcement, observing during extinction periods was less resistant to change. In addition, replicating the usual result, responding on the food key was generally more resistant to change in the presence of stimuli associated with higher reinforcement rates. These results suggest that quantitative descriptions of resistance to change derived with simple food-maintained responding may be applicable to observing, and perhaps by extension, to attending.

Animals↗

PubMed1994

[Participant observation as data collection method in nursing research].

Participant observation as data collection method in nursing research is explored in this article. The scientific basis of observation method comes from symbolic interactionism. Nature and epistemological starting points of the knowledge produced by observational method can vary depending on the purpose of the study. Participant observation is a process, which aims at scientific research through observer's presence in social situations. Fieldwork should be carefully prepared because the main problem in participant observation is observer's influence on phenomenon which is being studied. In the beginning of the field-work researcher tries to get a general view what happens in the situation. After the analysis the researcher can focus his observations according to his research problems and finally observe selectively. The data consists of record-keeping, descriptions and field-work note book. Participant observation is the most subjective observation method of data collection. By using triangulation a researcher can avoid his personal influence on results and make the validity of his study better. The researcher must take ethical issues into consideration when collecting data by participant observation.

Data Collection↗

PubMed2002

Morphometry of dermal collagen orientation by Fourier analysis is superior to multi-observer assessment.

In human dermis, collagen bundle architecture appears randomly organized, whereas in pathological conditions, such as scar tissue and connective tissue disorders, collagen bundle architecture is arranged in a more parallel fashion. Histological examination by one or two observers using polarized light is the most common method to determine collagen orientation. The hypothesis on which this study is based is that an objective image analysis technique, Fourier analysis, would improve the reliability (are the measurements reproducible?) and the accuracy (does the method measure what it is supposed to measure?) of collagen orientation assessment, compared with observer ratings. Fourier analysis was applied to 271 images of scar tissue and normal skin that were acquired by confocal laser-scanning microscopy. Observers rated the same areas using polarized light as well as the confocal microscopy images. Computer images consisting of different types of ellipses were generated with a fixed orientation. Observers and Fourier analysis evaluated the images to evaluate accuracy. The inter-observer reliability was acceptable when at least three observers rated polarized light images (r > 0.69), whereas two observers were sufficient for rating confocal microscopy images (r > 0.71). Fourier analysis correlated better with observer ratings of confocal microscopy images (r = 0.69) than with polarized light microscopy images (r = 0.42). Fourier analysis was more accurate than four observers for the evaluation of the 'true' orientation for almost all types of computer-generated images. For the first time it is shown that Fourier image analysis is suitable for the morphometry of dermal collagen orientation and leads to a superior measurement of collagen orientation compared with subjective histological evaluation by several experts. If an evaluation is performed by conventional light microscopy, at least three observers are required to attain an acceptable inter-observer reliability.

Adult↗

PubMed1998

Intra- and inter-observer variability in contouring prostate and seminal vesicles: implications for conformal treatment planning.

BACKGROUND AND PURPOSE: Accurate contouring of the clinical target volume (CTV) is a fundamental prerequisite for successful conformal radiotherapy of prostate cancer. The purpose of this study was to investigate intra- and inter-observer variability in contouring prostate (P) and seminal vesicles (SV) and its impact on conformal treatment planning in our working conditions. MATERIALS AND METHODS: Inter-observer variability was investigated by asking five well-trained radiotherapists of contouring on CT images the P and the SV of six supine-positioned patients previously treated with conformal techniques. Short-term intra-observer variability was assessed by asking the radiotherapists to contour the P and SV of one patient for a second time, just after the first contouring. The differences among the inserted volumes were considered for both intra- and inter-observer variability. Regarding intra-observer variability, the differences between the two inserted contours were estimated by taking the relative differences in correspondence to the CT slices on BEV plots (antero-posterior and left-right beams). Concerning inter-observer variability, the distances between the internal and external envelopes of the inserted contours (named projected diagnostic uncertainties or PDUs) and the distances from the mean inserted contours (named mean contour distances or MCDs) were measured from BEV plots (i.e. parallel to the CT slices). RESULTS: Intra-observer variability was relatively small (the average percentage variation of the volume was approximately 5%; SD of the differences measured on BEV plots within 1.8 mm). Concerning inter-observer variability, the percentage SD of the inserted volumes ranged from 10 to 18%. Differences equal to 1 cm in the cranio-caudal extension of P + SV were found in four out of six patients. The largest inter-observer variability was found when considering the anterior margin in the left-right beam of P top (MCD = 7.1 mm, 1 SD). Relatively high values for MCDs were also found for P bottom, for the posterior and lateral margins of P top (2.6 and 3.1 mm, respectively, I SD) and for the anterior margin of SV (2.8 mm, 1 SD). Relatively small values were found for P central (from 1.4 to 2.0 mm, 1 SD) and the posterior margin of SV (1.5 mm, 1 SD). CONCLUSIONS: The application of larger margins taking inter-observer variability into account should be taken into consideration for the anterior and the lateral margins of SV and P top and for the lateral margin of P. The impact of short-term intra-observer variability does not seem to be relevant.

Humans↗

PubMed2002

Observer variation in the sonographic measurement of optic nerve sheath diameter in normal adults.

AIM: To quantify the observer variation in the sonographic measurement of optic nerve sheath diameter (ONSD) in normal adults. MATERIALS AND METHODS: Sixty-seven normal adult volunteers underwent ultrasound examination of each eye by three independent observers using a 7 MHz sector probe. Three measurements were made of each eye by each observer and a mean value calculated for each eye. Median and 5th-95th centile values for both intra- and inter-observer variation were calculated for the three observers. RESULTS: The median intra-observer variation was +/-0.1 mm, with 5th-95th centile values of +/-0-0.4 mm. The median inter-observer variation was +/-0.2-0.3 mm, with 5th-95th centile values of +/-0-0.7 mm. Careful review of examination technique by the three observers after the first 17 examinations was shown to reduce both intra- and inter-observer variation. CONCLUSION: The sonographic measurement of ONSD is a readily learned, reproducible technique with low intra- and inter-observer variation. The average inter-observer variation (+/-0.2 mm) is comparable to the inherent variability of the ultrasound machine. The importance of standardisation of examination technique is stressed.

Adult↗

PubMed2001

The use of special observations: an audit within a psychiatric unit.

Observation is a fundamental skilled nursing intervention. Special observation is an intensified and often prolonged form of this intervention. Depending upon their nature, and the circumstances under which they are carried out, special observations may invoke varying degrees of stress in both the observer and the observed. They may also raise important ethical and significant financial questions. In psychiatry, special observations are usually imposed where a patient is assessed as representing some degree of risk to themselves or others because of their behaviours or potential behaviours. Special observations vary in their degree of intrusiveness and restrictiveness, and may arouse strong emotions in the patient and staff. Patients may be denied privacy for their most intimate needs, and staff may become a focus for patients' acting-out behaviours. Special observations may be medically imposed with minimal consultation with nursing staff, and where there is no nursing and medical staff agreement on their need, nursing staff may at times feel frustrated and powerless to reduce the patients' discomfort with their situation. This paper presents a study into the use of special observations on psychiatric inpatients across a range of clinical settings. The literature on special observations is reviewed, and the findings of an audit into the documentation of special observations is presented and discussed. The study sites comprised two open acute wards, one elderly functionally mentally ill assessment unit which also treats patients with eating disorders, and a secure high dependency unit, which provides rehabilitation within a secure environment for patients with severe and enduring mental illness.

Adult↗

PubMed2002

Concordance between self- and observer-ratings on Kasahara's Inventory for the Melancholic Type Personality.

The concordance between self- and observer-ratings was investigated for items on Kasahara's Inventory for the Melancholic Type Personality (KIMTP). Subjects consisted of 44 patients diagnosed with an ICD-10 diagnostic criteria for research (DCR) depressive episode (F32) or recurrent depressive disorder (F33) unipolar affective disorder, and 44 observers. Thirty-one of the 44 patients were diagnosed with endogenous depression. The observers consisted of five parents, eight children, thre siblings, 25 spouses, and three partners. Concordance was tested with Student's paired t-test and one-way analysis of variance intraclass correlation coefficient (ANOVA ICC). There was no statistical difference between the mean total self-rating score and the mean total observer-rating score in the endogenous depression group, but the mean total self-rating score was significantly higher than the mean total observer-rating score in the non-endogenous depression group. When the self and observer tests in this non-endogenous depression group were compared on an item-by-item basis, most items tended to receive higher scores from the self-raters than from the observer-raters. The ICC had good concordance for mean total self- and observer-ratings in the endogenous depression group but not the non-endogenous depression group. On an item-by-item basis, concordance was high between self- and observer-raters for more items in the endogenous depression group than in the non-endogenous depression group. There were some important differences between self- and observer-ratings for certain items in the non-endogenous depression group. Patients in this group tended to give higher scores to items representing Typus melancholicus in relation to scores given by observers.

Adult↗

PubMed2005

From fuzzy logic toward plurimonism: the science of active and empathic observation.

Plurimonism is a new philosophy and method of science. It holds that the revolution in computer science and artificial intelligence has reached the point that all the sciences in general can now account for the complex relations of an irreducible plurality of unique observers engaged in describing the same event. Plurimonism seeks to describe the conscious and unconscious relations of the scientific observer during the act of observation of a given event while preserving the historical uniqueness and indivisible identity of each such observer. Using the framework of plurimonism, we mathematically formulate the problem of empathy. This self-reflective mathematical model entails four components of the empathic process involving two observers. They are: 1) the self; 2) the self's-other; 3) the other; and 4) the other's-self. It measures the degree of accuracy of the therapist-observer's empathy, as well as conscious and unconscious processes involved in the patient-observer's idealization and the therapist-observer's confidence in clinical psychotherapy. Ratings are obtained from both patient and therapist from four different points of view. The plural views of the patient's global assessment of functioning (GAF) are from: 1) the therapist's view (TGAF); 2) the patient's view (PGAF); 3) the therapist empathic view (TEGAF), which represents the therapist's estimate of PGAF; and 4) the patient's empathic estimate of the TGAF. The GAF scale is the standard dimensional 100-point-scale measure used in psychiatry for recording a patient's functioning. The patient's estimate of the therapist's degree of accuracy as well as the therapist's confidence in his or her empathic accuracy is also represented. Three formulae are presented that describe the degree of the therapist's empathic accuracy, the patient's over-idealization/under-idealization, and the therapist's over-confidence/under-confidence. The concept of empathy is here restricted to mean the degree to which one observer can take the point of view of another observer when both are observing the same thing.

Cybernetics↗

PubMed2002

An observational study of antibiotic prescribing behavior and the Hawthorne effect.

OBJECTIVES: To assess whether prospective, observational study procedures, including questionnaires and audio recording, are associated with different patterns of physician diagnostic decision making and antibiotic prescribing. DATA SOURCES/SETTING: (1) Survey data from a prospective observational study of treatment patterns for children with acute upper respiratory illnesses (10/96-3/97) and (2) retrospective medical record abstraction data of nonobserved encounters for the same problems occurring during (10/96-3/97) and one year after (10/97-3/98) the observational study period. Ten pediatricians in two community practices were studied. STUDY DESIGN: Patterns of diagnoses recorded in the medical record and antibiotics ordered for visits occurring outside of the observational study (same time period and one year later) were compared with the pattern of diagnoses and antibiotics ordered during the observational study. DATA COLLECTION/EXTRACTION METHODS: For the observational study (10/96-2/97), diagnosis and treatment choices were obtained from questionnaires completed by physicians immediately following the visit. For the nonstudy encounters (10/96-3/97 and 10/97-3/98), data were abstracted from medical records one year after the observational study was completed. PRINCIPAL FINDINGS: The proportion of viral cases in which an antibiotic was prescribed was 29 percentage points lower for the observational study compared to the retrospective analysis (p < .05). In one of two study sites, the proportion of cases assigned a bacterial diagnosis was 29 percentage points lower in the observational study period compared to the retrospective study (p <.05). CONCLUSIONS: Observational study procedures including questionnaires and audio recording can affect antibiotic prescribing behavior. Future observational studies aimed at examining the frequency of inappropriate antibiotic prescribing should measure and adjust for the Hawthorne effect; without such adjustments, the results will likely underestimate the true degree of the problem. Future interventions aimed at decreasing inappropriate antibiotic prescribing should consider "harnessing" the Hawthorne effect through performance feedback to participating physicians.

Anti-Bacterial Agents↗

PubMed2002

How old is that child? Validating the accuracy of age assignments in observational surveys of vehicle restraint use.

OBJECTIVES: Many large scale observational studies of child restraint usage require observers to estimate the ages of the vehicle occupants. The accuracy of age assignments were assessed and possible methods to improve observational accuracy in research and field studies of child restraint use were identified. METHODS: The validation study was performed at fast food restaurants in a metropolitan area. Three, two person teams observed 449 occupants of vehicles with at least one child passenger. The drivers were then interviewed to obtain the actual ages of the vehicle occupants. The primary outcome measure was the per cent of age assignments that were correct by age category (infant, toddler, school age, teen, adult). The observers had previously conducted a statewide child restraint observation study and were trained in estimating age categories. RESULTS: A total of 391 (87%) of the 449 occupants were assigned to their correct age categories. Incorrect assignments were more common among infants (22% incorrect), but few infants (nine) were observed. The most frequent error was classifying adults (19 years and older) as teenagers (13-18 years). CONCLUSION: Trained, experienced observers approached 90% accuracy in their assignment of children to specific age categories. Additional study is required to determine whether these results are applicable to different age categories and observers. It is recommended that the National Highway Traffic Safety Administration, the Centers for Disease Control and Prevention, state and local agencies, and other sponsors of observational surveys consider observer competence as an important variable. The validity of age assignments can be assessed by randomly interviewing a sample of drivers. More accurate age estimates will improve decisions regarding prevention programs, funding, and policies.

Adolescent↗

PubMed1991

Observer performance in the assessment of periapical pathology: a comparison of panoramic with periapical radiography.

Observer performance in the assessment of the periapical pathology from panoramic and periapical radiography was examined. Five endodontists, five general practitioners and five oral radiologists were asked to assess the periapical status of 117 teeth. The observers assessed the panoramic and periapical radiographs of the teeth, which were evenly distributed throughout the jaws with a 50% probability that either an osteolytic or sclerotic lesion was present. The results of the comparison between panoramic and periapical radiography were influenced by the selection of observers. When the oral radiologists acted as observers, the mean P(A) value for periapical radiography was higher than for panoramic radiography (P less than 0.001), resulting in periapical radiography presenting a higher overall diagnostic accuracy than panoramic radiography for all 15 observers (P less than 0.01). There was, however, no difference between panoramic and periapical radiography when the two groups of endodontists and general practitioners acted as observers. The comparison of the three groups of observers showed no difference between their diagnostic accuracy when assessing panoramic radiographs. With periapical radiography, the oral radiologists demonstrated a higher diagnostic accuracy than the endodontists (P less than 0.05). The observers in each group with the highest diagnostic accuracy also had the highest intra-observer agreement. The mean intra-observer agreement of the five general practitioners was higher than those of the other two groups of observers for panoramic radiography. For periapical radiography, the mean agreement rates of the groups were comparable.

Adult↗

PubMed2000

Observer variation in the diagnosis of thyroid disorders. Criteria for and impact on diagnostic decision-making.

The thesis is concerned with the reliability of thyroid diagnostic modalities. When no "true" diagnosis was available the reliability could not be evaluated by assessing the accuracy; in these cases the reproducibility was evaluated. This was done by evaluating the observer variation: comparison of observers' evaluation in pairs was assessed. The observer variation was expressed by the kappa coefficient, which adjusts to the amount of agreement that can be expected to occur by chance alone. Clinical estimation only of thyroid functional status was subject to considerable observer variation. Likewise clinical estimation the thyroid gland (size and morphology) was subject to considerable observer variation, and the observer variation was greatest concerning the palpation of a solitary thyroid nodule where even experienced doctors had difficulties in reproducing their own evaluations. In contrast high reproducibility was found concerning the interpretation of routine thyroid blood tests. Thyroid scintigram is not suitable for thyroid size estimation. Assessment of thyroid morphology (diffuse, multinodular, solitary hot or cold lesion) based on scintigram alone seldom resulted in acceptable reproducibility: four doctors diagnosed a solitary cold lesion in 100 of 480 scintigrams, however, they only agreed in 30 of the cases. A solitary cold lesion may in a few per cent of the cases imply malignancy and will therefore lead to further investigations. The reproducibility was not improved when the doctors had additional access to patient history and clinical examination as well as the scintigram. Ultrasound is increasingly often regarded as the "true" diagnosis in the morphological description of the thyroid gland. In a study of two specialists in thyroid ultrasound these descriptions were, however, found not to be reproducible. Thus ultrasound should be applied with caution as the golden standard with regard to thyroid type. It has been demonstrated that thyroid imaging is subject to considerable observer variation. This has great implications when thyroid imaging is used as the golden standard, for example when patients are selected for scientific studies. Furthermore, this may influence the comparison of different studies because of inconsistency of the material included. Therefore the observer variation should appear from description of material and methods in scientific studies. Palpation of thyroid size is neither accurate nor reproducible if an exact volume is aimed at. A rough division into small, medium, and large goitres is reproducible and rather accurate and may therefore be applied. In a prospective randomised study it was demonstrated that this division could replace ultrasound estimation of thyroid size in the calculation of 131I dose in the treatment of hyperthyroidism. Evaluation of thyroid functional status cannot be based on patient history and clinical examination alone, it should include thyroid blood tests. Exact estimation of thyroid size should be performed by means of ultrasound. When morphology of the thyroid is assessed the observer variation should be kept in mind. The existence of observer variation implies uncertainty concerning patient material and inclusion criteria in scientific studies. It may complicate comparison of scientific results. In thyroid diagnostic decision-making doctors should keep in mind that even though there is agreement concerning thyroid blood tests there is not agreement concerning thyroid imaging and the clinical evaluation of patients suspected of thyroid disorders. The patients may experience these disagreements even if the same doctor follows them. Doctors are obliged to use the existing modalities and should be aware of not only problems with technology but also variations originating from the observers, the doctors themselves--the human factor.

Humans↗

PubMed1996

Determination of prostatic volume with transrectal ultrasound: A study of intra-observer and interobserver variation.

PURPOSE: We assessed the intra-observer and interobserver variation in measurements of prostatic volume using transrectal ultrasound. MATERIALS AND METHODS: Two volume estimations were performed by 1 observer in 40 patients and by 2 observers in 75. RESULTS: Mean prostatic volumes measured ranged from 18.9 to 87.0 ml. (median 39.8) for 1 observer and from 15.5 to 95.4 ml. (median 42.4) for 2 observers. The mean difference plus or minus standard deviation and limits of agreement between the paired volume estimations were 0.1 +/- 3.3 ml. and -6.5 +/- 6.7 ml., respectively, for 1 observer, and -0.3 +/- 5.3 ml and -10.9 to 10.3 ml., respectively, for 2 observers. The mean difference was 9.8% for 2 observers. The mean difference was 9.8% for 2 observers compared to 4.6% for 1. CONCLUSIONS: The results show that there is considerable variation in repeated measurements of prostatic volume and the variation is greatest for 2 observers compared to 1 observer.

Adult↗

PubMed2006

Neural processing of observed oro-facial movements reflects multiple action encoding strategies in the human brain.

In this experiment, the oscillatory responses of the MEG were characterized during the observation of four viewing conditions: (a) observation of mouth movements, (b) observation of a non-biological motion stimulus (a mechanical aperture opening and shutting), (c) observation of object-directed mouth movements and (d) observation of speech-like mouth movements. Data were analyzed using synthetic aperture magnetometry (SAM) in three frequency bands, beta (15-35 Hz), gamma (35-70 Hz) and alpha/mu (8-15 Hz). Results showed that observations of biological motion resulted in beta desynchronization over lateral sensorimotor areas, while observations of non-biological motion resulted in a more medial desynchronization, an effect that may be related to the processing of a structured event sequence. Observation of linguistic movements resulted in less alpha/beta desynchronization in posterior brain regions in comparison to biological motion stimuli, suggesting that linguistically-relevant stimuli are processed with different neuronal systems than those recruited by normal action observation. We suggest that non-linguistic actions recruit dorsal systems while linguistic actions engage ventral processing systems. Object-directed movements showed the largest sensorimotor activations, suggesting that, as is the case for observations of hand movements, motoric processing is particularly sensitive to the viewing of goal-directed actions. Taken together, the results indicate that the brain utilizes multiple action encoding strategies, tailored to the function of the observed movement.

Adult↗

PubMed2003

A new paradigm to analyze observational learning in rats.

A new paradigm of learning was developed through observational training in which rats repeatedly observed companion rats performing different spatial tasks. Observer animals were separately housed in small cages suspended over a water maze tank. They repeatedly observed companion actor rats performing spatial tasks differing according to the experimental requirements. After the observational training, observer animals were or not surgically hemicerebellectomized. This surgical ablation was performed to block any further acquisition of new behavioral strategies during actual performance of swimming task. When cerebellar symptomatology stabilized, observer animals were actually tested in the Morris Water Maze (MWM) task they had previously only observed. The observer rats displayed exploration abilities that closely matched the previously observed behaviors. The results obtained indicate that it is possible to learn complex behavioral strategies by observation using this new protocol. Furthermore, acquisition of the single facets that form the behavioral repertoire can be separately studied.

Animals↗

PubMed2005

Differential activation of pre-SMA and SMA proper during action observation: effects of instructions.

Many neurophysiological studies give evidence for a matching system between action observation and imitation. We used functional MRI to investigate the effects of different instructions for observing identical stimuli of whole-body gymnastics movements. The imitative-like observation mode asked normal human participants to observe the sequence containing repetitive parts and to subsequently imagine the observed movements in the first-person perspective. The evaluative observation mode asked the participants to carefully observe and judge movement accuracy and consistency in the repetitive sequence. We hypothesized that the supplementary motor area would be specifically involved in performing the observational tasks. Results indicate that the SMA proper is generally activated during observation of whole-body gymnastic movements and shows pronounced activation in imitative-like observation mode. Pre-SMA activity can be differentially modulated by instructions related to the observation task.

Adult↗

PubMed1988

Observation of head trauma patients at home: a prospective study of compliance in the rural south.

A prospective study was conducted to test the reliability of at-home observation of head trauma victims in the rural South among a population of low educational level. During a four-month period, 99 patients entered and 90 patients finished the study. In all cases, an individual was identified as willing to accept the responsibility of observing the patient. The observer received written and verbal instructions to stay with the patient for 24 hours and to wake the patient every four hours during that time. Patients then were contacted seven to nine days after their injury and questioned as to their present symptoms and observer compliance. For patients under 15 years of age (n = 34), the observer was questioned. Thirteen percent of the observers did not remain with the patient for 24 hours, 16% passed the responsibility of observation to another individual, and 71% awoke the patient as instructed. Observers who were not the patient's mother were significantly more likely to abandon the patient during the first 24-hour period. Observer compliance for patient awakening significantly decreased with the increase in patient age. When spouses and live-in friends were combined as a group of observers and compared with parents, the parents awoke the patient significantly more often. The authors conclude that in this population, at-home observation of head trauma patients, particularly those more than 25 years old, may not be reliable. Special attention should be directed toward the care of these patients.

Adolescent↗

PubMed2001

Modulation of spinal excitability during observation of hand actions in humans.

There is growing evidence that observation of actions performed by other individuals activates observer's cortical motor areas. This matching of observed actions on the observer's motor repertoire could be at the basis of action recognition. Here we investigated if action observation, in addition to cortical motor areas, involves also low level motor structures mimicking the observed actions as if they were performed by the observer. Spinal cord excitability was tested by eliciting the H-reflex in a finger flexor muscle (flexor digitorum superficialis) in humans looking at goal-directed hand actions presented on a TV screen. We found that, in the absence of any detectable muscle activity, there was in the observers a significant modulation of the monosynaptic reflex size, specifically related to the different phases of the observed movement. The recorded H-reflex rapidly increased in size during hand opening, it was depressed during hand closing and quickly recovered during object lifting. This modulation pattern is, however, opposite to that occurring when the recorded muscles are actually executing the observed action [Lemon et al. (1995) J. Neurosci., 15, 6145-56]. Considering that, when investigated at cortical level the modulation pattern of corticospinal excitability replicates the observed movements [Fadiga et al. (1995) J. Neurophysiol., 73, 2608-2611], this spinal 'inverted mirror' behaviour might be finalised to prevent the overt replica of the seen action.

Adult↗