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PubMed2005

The influence of attention and age on the occurrence of mirror movements.

This study utilised a finger force task to investigate the influence of attention and age on the occurrence of motor overflow in the form of mirror movements in neurologically intact adults. Forty right-handed participants were recruited from three age groups: 20-30 years, 40-50 years, and 60-70 years. Participants were required to maintain a target force using both their index and middle fingers, representing 50% of their maximum strength capacity for that hand. Attention was directed to a hand by activating a bone conduction vibrator attached to the small finger of that hand. Based on Cabeza's (2002) model of hemispheric asymmetry reduction in older adults, it was hypothesised that mirror movements would increase with age. Furthermore, it was expected that when the attentional demands of the task were increased, motor overflow occurrence would be exacerbated for the older adult group. The results obtained provide support for the model, and qualified support for the hypothesis that increasing the attentional demands of a task results in greater motor overflow. It is proposed that the association between mirror movements and age observed in this study may result from an age-related increase in bihemispheric activation that occurs in older adults, who, unlike younger adults, benefit from bihemispheric processing for task performance.

Adult↗
PubMed2005

Novel silver nanostructures from silver mirror reaction on reactive substrates.

Novel silver clusters have been prepared by simply carrying out the silver mirror reaction on certain reactive substrates. Leaflike fractal silver microstructures and perpendicularly aligned silver nanosheets were produced on a commercially available copper foil and sandpaper-rubbed copper foil, respectively. The surface features of copper foils and the chemical state of Cu atoms play important roles in regulating the morphological structures of the resulting silver clusters. Silver nanoclusters with various morphologies ranging from the leaflike to flowerlike hierarchical structures can be produced from the silver mirror reaction on commercially available copper foils after being treated with a dilute aqueous HCl solution under different conditions. The aqueous solution of silver nanosheets shows an optical absorption spectrum with a broad light-scattering peak at about 350 nm, compared to a corresponding surface plasmon absorption band around 430 nm for silver nanoparticles from the conventional silver mirror reaction on glass.

Journal Article↗
PubMed2006

Lifting the mirror symmetry of metal surfaces: decoupling the electronic and physical manifestations of surface chirality.

Naturally occurring metal surfaces possess planes of mirror symmetry on the nanometer-length scale. This mirror symmetry can be lifted and chirality "physically" conveyed onto a surface by adsorbing a chiral molecule. Until now, it has not been known whether the conveying of chirality is limited to just the physical structure or whether it goes deeper and permeates the electronic structure of the underlying surface. By using optically active second harmonic generation (OA-SHG), it is demonstrated that the adsorption of some, but not all, chiral molecules can reversibly, and without significant structural rearrangement, measurably lift the mirror symmetry of the surface electronic structure of a metal. It is proposed that the ability of a chiral molecule to place a significant "chiral perturbation" on the electronic structure of a surface is correlated to its adsorption geometry. The microscopic origins of the observed optical activity are also discussed in terms of classical models of chirality. The results of the study challenge current models of how chiral adsorbates induce enantioselectivity in the chemical/physical behavior of heterogeneous systems, which are based on geometric/stereochemical arguments, by suggesting that chiral electronic perturbations could play a role.

Metals↗
PubMed1993

Mirror-image matching and mental rotation problem solving by baboons (Papio papio): unilateral input enhances performance.

Three experiments, using a matching-to-sample procedure, were conducted to examine hemispheric specialization in mirror-image discrimination and mental rotation in baboons (Papio papio). In Experiment 1, no significant difference was found in discrimination of mirror-image and asymmetric pattern stimuli. In Experiment 2, orientation discrimination was assessed within the left (LVF) and right (RVF) visual half-fields. An RVF advantage was found in accuracy for asymmetric patterns, whereas an LVF advantage was found for discrimination of mirror-image stimuli. No significant relation was found between angular disparity of the stimuli and response time. Experiment 3 examined the effect of bilateral visual input on accuracy and response time. Significantly lower accuracy and longer response times were found for bilateral compared with unilateral visual input.

Animals↗
PubMed1990

The mirror effect in recognition memory: data and theory.

The mirror effect is a regularity in recognition memory that requires reexamination of current views of memory. Five experiments that further support and extended the generality of the mirror effect are reported. The first two experiments vary word frequency. The third and fourth vary both word frequency and concreteness. The fifth experiment varies word frequency, concreteness, and the subject's operations on the words. The experiments furnish data on the stability of the effect, its relation to response times, its extension to multiple mirror effects, and its extension beyond stimulus variables to operation variables. A theory of the effect and predictions that derive from the theory are presented.

Humans↗
PubMed1994

Mirror effect in frequency discrimination.

In recognition, types of stimuli that are relatively easy to classify as old when old are also relatively easy to classify as new when new. The experiments reported here extend this mirror effect to discriminations among above-zero situational frequencies. Frequency discrimination exhibits a mirror effect when words are compared with nonwords or when low-linguistic-frequency words are compared with high-linguistic-frequency words. Accurate knowledge concerning the relative memorability of test items is neither necessary nor sufficient for the presence of a mirror effect.

Humans↗
PubMed1998

Response distribution as an explanation of the mirror effect.

Response distribution has recently been proposed as an explanation of the mirror effect in recognition memory. According to the proposal, participants presented with distinctive sets of items (e.g., low- and high-frequency words) vary their responses to give an equal number of positive responses (e.g., the sum of hits and false alarms) to each set. Four experiments tested this proposal. Two experiments showed that the mirror effect is present in the absence of distinctive sets of items. Two experiments showed that the mirror effects is present in the absence of response equalization. Wherever the response distribution hypothesis can be tested, it fails.

Adult↗
PubMed2000

Recollection and familiarity through the looking glass: when old does not mirror new.

The authors use the qualitative differences logic to demonstrate that 2 separate memory influences underlie performance in recognition memory tasks, familiarity and recollection. The experiments focus on the mirror effect, the finding that more memorable stimulus classes produce higher hit rates but lower false-alarm rates than less memorable stimulus classes. The authors demonstrate across a number of experiments that manipulations assumed to decrease recollection eliminate or even reverse the hit-rate portion of the mirror effect while leaving the false-alarm portion intact. This occurs whether the critical distinction between conditions is created during the test phase or manipulated during the study phase. Thus, when recollection is present, it dominates familiarity so that the hit-rate portion of the mirror effect primarily reflects recollection; when recollection is largely absent, the opposite pattern associated with the familiarity process emerges.

Adult↗
PubMed2003

To see or not to see: effects of exercising in mirrored environments on sedentary women's feeling states and self-efficacy.

Effects of a mirrored exercise environment and body image concerns on changes in exercise-induced feeling states and self-efficacy were examined among 58 sedentary women (mean age = 20.7 years). Participants performed a 20-min bout of exercise in front of either a mirrored or a nonmirrored wall. Feeling states and self-efficacy were measured pre- and postexercise. Multilevel linear modeling indicated that regardless of their level of body image concern, women in the mirrored condition felt worse after exercising than women in the unmirrored condition. There were no effects of the environment or body image on self-efficacy. Results are consistent with predictions of objective self-awareness theory and have implications for promoting exercise among sedentary women.

Adult↗
PubMed2005

Distinctiveness and the recognition mirror effect: evidence for an item-based criterion placement heuristic.

Superior detection and rejection of 1 versus another class of items during recognition is called the mirror effect. Some mirror effects may involve strategic criterion adjustments based on item distinctiveness and its relation to memorability. Three experiments demonstrated mirror effects for known versus unknown scenes and 1 suggested a similar pattern for faces. In opposition to preexperimental familiarity, lures from known and frequently encountered locations were confidently rejected more often than unknown lures. Forgetting and speeding recognition reversed this lure response pattern, suggesting abandonment of strategic adjustment in favor of a single fixed criterion. With sufficient response time and recent encoding, observers demand more evidence for conceptually distinctive items, perhaps because such items typically foster vivid recollection during retrieval.

Cues↗
PubMed1975

Interocular transfer of lateral mirror-image discriminations by cats: evidence of species differences.

Interocular transfer of mirror-image discriminations has been shown to be paradoxical in split-chiasm monkeys tested in a lighted Wisconsin General Test Apparatus (WGTA) with 3-dimensional forms, but veridical in split-chiasm cats tested in a darkened 2-choice discrimination box with transilluminated patterns. In the present study, 8 split-chiasm cats showed veridical interocular transfer of a mirror-image and a non-mirror-image discrimination in a WGTA or a 2-choice discrimination box. On the basis of the testing parameters used, it is argued that the discrepancy in the literature arises from a species difference (having a behavioral rather than a gross neurological basis), and not from differences in behavioral testing apparatus or mode of stimulus presentation.

Animals↗
PubMed1998

Fringe is essential for mirror symmetry and morphogenesis in the Drosophila eye.

An early event in Drosophila eye development is the division of the eye disc into dorsoventral domains. The dorsoventral pattern is displayed in the adult compound eye as a distinct mirror symmetry across the dorsoventral midline or equator. The dorsoventral axis is also implicated in organizing early development of the eye, as retinal differentiation is initiated at the posterior dorsoventral midline. Here we show that Fringe is expressed specifically in the ventral half of the undifferentiated eye disc, thus creating a dorsoventral boundary. Ectopic Fringe borders that are generated by clones of fringe cells can reverse the planar polarity of photoreceptor clusters, indicating that the Fringe boundary is crucial for the induction of mirror symmetry. Lack of a Fringe boundary disrupts equatorial expression of Notch signalling proteins and causes a complete failure of eye development. Our results indicate that the formation of the Fringe boundary and subsequent Notch signalling at the equator are essential for organizing mirror symmetry and eye morphogenesis.

Animals↗
PubMed2005

Understanding emotions in others: mirror neuron dysfunction in children with autism spectrum disorders.

To examine mirror neuron abnormalities in autism, high-functioning children with autism and matched controls underwent fMRI while imitating and observing emotional expressions. Although both groups performed the tasks equally well, children with autism showed no mirror neuron activity in the inferior frontal gyrus (pars opercularis). Notably, activity in this area was inversely related to symptom severity in the social domain, suggesting that a dysfunctional 'mirror neuron system' may underlie the social deficits observed in autism.

Autistic Disorder↗
PubMed2000

Studies of a magnetically focused electrostatic mirror. II. Aberration corrections

A magnetically focused electrostatic mirror is shown to be able to correct the spherical and chromatic aberrations of a probe forming system simultaneously. The probe forming system comprises a uniform magnetic lens and a uniform electrostatic mirror. Previous theoretical investigations showed that the spherical and chromatic aberration coefficients of these two components are the same values but with opposite sign, whose combination will therefore be free from aberrations. The experimental arrangement used a solenoid to produce a uniform magnetic field, and a series of plate electrodes to produce a uniform electrostatic field. These fields are shown to satisfy the experimental requirements. By deliberately changing the extraction voltage to defocus the electron beam, the author is able to observe correction of chromatic aberration by one order of magnitude. By deliberately changing the lens field and the mirror field, the author is able to observe the reduction of the asymmetry caused by the spherical aberration, which the author believes also indicates correction by one order of magnitude.

Journal Article↗
PubMed1998

Perforating eye injuries from external rear vision mirrors.

PURPOSE: To highlight external rear vision mirrors as a cause of ocular injuries in motor vehicle accidents. METHODS: Three cases of perforating eye injuries due to shattered external rear vision mirrors in motor vehicle accidents are described. The relevant Australian design rules are reviewed. RESULTS/CONCLUSION: External rear vision mirrors can be responsible for serious ocular injuries in motor vehicle accidents. Further investigation of the incidence of such injuries is required to determine whether vehicle manufacturing methods and the design rules covering their production warrant revision.

Accidents, Traffic↗
PubMed1978

Hereditary mirror movements--a case report.

A five-year-old girl with abnormal mirror movements is described. The phenomenon is observed in the distal parts of the extremities and is most marked in the hands. An extensive neuropediatric examination including computerized tomography of the brain has not revealed any further abnormalities, nor has it been possible to identify the pathogenetic mechanism. The clinical picture corresponds to that previously reported in cases of hereditary mirror movements--a condition with unknown pathogenesis affecting individuals that in other respects are neurologically normal. The disorder is considered to be dominantly inherited but in this case available data suggest a recessive mode of inheritance. There is no doubt that the girl of this report is getting increasingly embarrassed by her condition. Obviously mirror movements of this degree constitute a slight to moderate handicap.

Child, Preschool↗
PubMed2001

A case of Standford type B aortic dissection involving a right-sided aortic arch with mirror-image branching and right-sided descending aorta.

Isolated right aortic arch with mirror-image branching is a rare congenital anomaly. To date, no case has been reported for aortic dissection involving a right aortic arch with mirror-image branching. We report here on a case involving a 58-year-old man in whom expanding type B aortic dissection was demonstrated in the right aortic arch with mirror-image branching and a right descending aorta. The patient was successfully treated by interposition of a prosthetic graft via a right posterolateral thoracotomy approach. We also reviewed the literature.

Aortic Dissection↗
PubMed1988

Tactile recognition of mirror images by children: intermanual transfer and rotation of the palm.

In order to evaluate the importance of the axis of stimulus presentation, inter- and intramanual recognition of mirror pairs was studied with the stimulus materials aligned along the front/back axis (whereas in previous work the mirror pairs were aligned along the left/right axis). Children were allowed to feel shapes with the whole hand, with only four fingers (excluding the thumb), or with only the index finger. After learning with one hand, recognition was tested in experiment 1 with the other hand; after learning with one orientation of the hand (palm down or up), recognition was tested in experiment 2 with the other orientation (palm up or down) of the same hand; after learning with one coronal alignment of the hand (to the left or right), recognition was tested in experiment 3 with the other alignment (to the right or left), but without rotation, of the same hand. Significantly fewer intermanual recognition errors were made on mirror pairs with the materials oriented along the front/back axis than in previous work when oriented along the left/right axis. This supports the suggestion that such errors arise when the stimuli are oriented along the left/right axis during formation of the memory trace. The same trend was unexpectedly obtained for intramanual recognition errors (after rotation of the hand). These errors (after hand rotation) are largely due to coding with respect to the hand; they are reduced when the hand is not aligned with the body axis, since then coding can also occur in relation to the environment.

Attention↗