Mirror Test Research Articles

Supplemental Material for Investigation of Mirror-Self Recognition in Ravens (Corvus corax)

Supplemental Material for Investigation of Mirror-Self Recognition in Ravens (Corvus corax)

Long focal length aspherical mirror testing with CGH and auxiliary lenses (invited)

Long focal length aspherical mirror testing with CGH and auxiliary lenses (invited)

Understanding the self in relation to others: Infants spontaneously map another's face to their own at 16-26 months.

The current study probed whether infants understand themselves in relation to others. Infants aged 16-26 months (n=102) saw their parent wearing a sticker on their forehead or cheek, depending on experimental condition, placed unwitnessed by the child. Infants then received a sticker themselves, and their spontaneous behavior was coded. Regardless of age, from 16 months, all infants who placed the sticker on their cheek or forehead, placed it on the location on their own face matching their parent's placement. This shows that infants as young as 16 months of age have an internal map of their face in relation to others that they can use to guide their behavior. Whether infants placed the sticker on the matching location was related to other measures associated with self-concept development (the use of their own name and mirror self-recognition), indicating that it may reflect a social aspect of children's developing self-concept, namely their understanding of themselves in relation and comparison to others. About half of the infants placed the sticker on themselves, while others put it elsewhere in the surrounding, indicating an additional motivational component to bring about on themselves the state, which they observed on their parent. Together, infants' placement of the sticker in our task suggests an ability to compare, and motivation to align, self and others.

Effects of oxybenzone on zebrafish behavior and cognition

The increased ultraviolet (UV) radiation on the Earth's surface increased the need for UV filters products. One of the most used is oxybenzone, which is indiscriminately released in the environment. Oxybenzone's ecotoxicological effects on physiology have been investigated because of the bioaccumulation and action as an endocrine disruptor. However, little is known about its effects on behavior or cognition. In this study, we approach the effects of short-term oxybenzone exposure on locomotion, anxiety-like, social behavior, and short-term memory in zebrafish (Danio rerio). Adult zebrafish were exposed to oxybenzone 10, 100 and 1000 μg L−1 for 15 days and then tested (novel tank, shoal preference, mirror test, and T-maze with novelty). Fish exposed to oxybenzone showed reduced locomotion, decreased anxiety-like behavior, less time near/interacting with the shoal, fewer interactions with the mirror image, and decreased exploration of the novel arm in the T-maze test. These results suggest that oxybenzone affects perception, increases risk-taking, impairs proper aggressive response, and jeopardizes the animals' ability to retain information. These results reinforce the risk posed by products discarded into the aquatic ecosystems, especially those with underestimated toxic potential.

Editor’s Note

Editor’s Note

Orthogonal ray interferometer: modification for testing convex and concave mirror surfaces

A non-contact optical method for testing of large concave and convex mirrors both spherical and aspheric is presented. It is based on the orthogonal ray interferometer modification. The point source is placed near the testing mirror and the chief ray propagates normally to its axis. The information about a tangential profile of testing mirror is contained in an interference pattern that is a result of superposition between two wavefronts, the first is reflected from the mirror, the second bypasses the mirror. Testing of the entire surface is carried out by rotating the mirror. Interferogram decoding method and algorithm for determination of an error of the testing surface are presented. The proposed method does not require bulky additional optical components what differs it from existing methods and makes promising primary for testing large astronomical mirrors. Furthermore, the method is universal and suited for surfaces with various geometrical parameters. The scheme with some modification of the present method is applied for surfaces without axis of rotational symmetry or freeform surfaces.

Self-Processing and Self-Face Reaction Time Latencies: A Review.

In this article, we detail the advantages of self-face identification latencies over more traditional tests of mirror self-recognition. Using reaction time latencies (measured in milliseconds) to identify different dimensions of the self, instead of relying on a simple dichotomous pass/fail mirror mark-test outcome, enables investigators to examine individual differences in self-processing time. This is a significant methodological step forward with important implications. The point of departure for our article is to detail research we and others have conducted on latencies for self-face identification, to show how self-processing occurs in the right side of the brain, how schizophrenia is a self-processing disorder, how self-face reaction time latencies implicate the existence of an underlying multiple modal self-processing system, and to explore ideas for future research.

Dust generation and accumulation in JET-ILW: morphology and stability of co-deposits on main plasma-facing components and wall probes

Dust particles and co-deposits were sampled for the first time from beryllium limiters and bulk tungsten divertor (both after ILW-3), and test mirrors from the main chamber after ILW-2 and ILW-3. The focus was on the morphology of molten particles and metal outgrowths. In parallel, the stability of beryllium layers under the impact of hot water was examined on limiters and Be coatings. The study performed by several microscopy methods including SEM, AFM, FIB, TEM and Be-sensitive EDX has revealed: (i) an asymmetric distribution of Be particles with the largest objects (125-550 μm) on side surfaces of the Be tile: (ii) the presence of highly porous particles, resembling blisters; (iii) very few thin flakes of co-deposits on the divertor, on the shadowed edge of lamella; (iv) the elemental composition and internal structure of the needle-shaped outgrowths on the mirrors: MoO; (v) no detectable impact of water on the beryllium morphology.

Management of patients with facial burns

People with severe facial burns face a long process of readjustment to social life. Altered body image challenges their identity and daily interactions. Themirror test, in which nurses help patients to look at their wounds, is a key step in the care given by carers, but also in the transition from the hospital world to the social world.

Chemically mediated self-recognition in sibling juvenile common gartersnakes (Thamnophis sirtalis) reared on same or different diets: evidence for a chemical mirror?

Abstract Although self-recognition or self-awareness has been studied with the visually-based mirror test, passed by several species, primarily apes, the possibility of a chemically-based analogue is controversial. Prior studies suggested that chemical self-recognition may occur in some squamate reptiles. To evaluate this possibility, we studied 24 individually housed gartersnakes, Thamnophis sirtalis, raised from birth on either earthworm or fish diets and tested 12 male and 12 female snakes with cage liners that were either clean, their own, or from same-sex siblings fed their own or the opposite diet. Tongue flicking and activity were recorded in 30-minute video-recorded trials in a balanced design. After initial habituation to the stimuli, male, but not female, snakes discriminated between their own stimuli and those from littermates fed the same diet. Combined with other data and studies, the possibility that a chemical ‘mirror’ form of self-recognition exists in squamate reptiles is supported.

Through a glass darkly? Divergent reactions of eight Lake Tanganyika cichlid species towards their mirror image in their natural environment

AbstractBehavioural reactions towards a mirror image are frequently used to measure individual aggression in a standardized way, especially in fishes. However, this approach was criticized recently on several grounds. One point of concern is that mirror tests are often conducted under highly artificial laboratory settings, while there exists a lack of knowledge of how individuals will react towards their reflection in the wild. We measured the responses of eight sympatric lamprologine cichlid species towards their mirror images in their natural environment in Lake Tanganyika. All species reacted by showing aggression towards their mirror image. The occurrence of overt and restrained aggression varied between species, reflecting species‐specific aggressive behaviours. The finding that larger species showed a higher amount of overt attacks further supports this interpretation. A commonality across all species was that aggression escalated over time, resembling behavioural patterns during prolonged aggressive encounters between life opponents with similar resource holding potential. These results shed light on the behaviour of closely related fish species towards their mirror image under natural conditions and contribute knowledge to the ongoing discussion on the suitability of mirror tests when measuring aggression.

Ontogeny and personality affect inhibitory control in guppies, Poecilia reticulata

In mammals and birds, interindividual variability in inhibitory control is often explained by developmental changes and personality. Teleost fish exhibit one of the highest levels of intraspecific variability in inhibitory control described in vertebrates, but the underlying causes have not been fully described. We investigated the effects of development and personality on inhibitory control of a teleost fish, the guppy. In experiment 1, we compared the performance of 10-, 20-, 40- and 90-day-old guppies in the cylinder task, which requires subjects to inhibit the tendency to swim towards a food reward. We found that guppies of all ages tested were capable of executing the motor inhibition required by the task. However, there was a U-shaped effect of age on performance: 10- and 90-day-old guppies had lower inhibitory control compared to 20- and 40-day-old guppies. In experiment 2, we correlated guppies’ inhibitory control performance with three tests aimed to assess different personality trials: boldness (scototaxis test), exploration (open-field test) and sociability (mirror test). We found a significant covariation only for the open-field test, which might indicate that more explorative guppies exhibited greater inhibitory control. Overall, this study suggests that ontogeny and personality may have a role in determining interindividual differences in a teleost fish similar to that described in mammals and birds. • We studied the effects of ontogeny and personality on inhibitory control in a teleost. • Fish of all ages tested showed inhibitory control in the cylinder task. • 10- and 90-day-old fish had lower inhibitory control than 20- and 40-day-old fish. • More explorative individuals exhibited greater inhibitory control. • Boldness and sociability did not correlate with inhibitory control.

Open field mirror test as a tool for the assessment of visual functions in rats with streptozotocin-induced diabetes

To evaluate the use of mirror test in an open field arena as a visual function assessment tool in a rodent model of diabetes. Male Sprague-Dawley rats were divided into diabetic rats, that received intraperitoneal streptozotocin (55 mg/kg body weight) for induction of diabetes, and control rats that similarly received citrate buffer. Rats with a blood glucose level of more than 20 mmol/L were considered diabetic. Blood glucose was monitored weekly throughout the experimental period. General behavioural assessment of the rats was done at week 12 post-induction using open field arena, followed by visual-behavioural assessment with mirror and reversed mirror added in the arena. Subsequently, rats were euthanised and subjected to haematoxylin and eosin staining (H&E) staining to assess changes in retinal morphology. In the open field test, diabetic rats showed a lesser number of zone crossings (3.73-fold, p<0.001), total distance travelled (2.02-fold, p<0.001), number of rearing episodes (2.22-fold, p<0.001) and number of grooming episodes (4.33-fold, p<0.01) but a greater number of freezing episodes (2.47-fold, p<0.001) and number of the faecal pellet (4.17-fold, p<0.01) compared to control rats. Control rats spent more time with higher zone entries toward mirrored than non-mirrored and reversed mirror zones (p<0.05 and p<0.01 respectively), whereas diabetic rats showed no preference for zones. Normal rats also showed higher freezing episodes within the mirrored zone compared to diabetic rats (2.00-fold, p<0.05). The retinal morphometry showed significant thinning of various retinal layers in the diabetic group compared to control rats. Visual behavioural activities of diabetic rats in an open field arena with the presence of a mirror could detect the presence of visual loss. Changes in visual functions positively correlated with changes in retinal morphology. Therefore, an open field mirror test could be used as an alternative for assessing visual function in the rodent model of diabetes.

Small Mirrors Do the Trick: A Simple, but Effective Method to Study Mirror Self-Recognition in Chimpanzees

Mirror self-recognition (MSR) is considered an indicator of self-awareness. Standardized mirror tests reveal compelling evidence for MSR in a few non-human species, including all great apes. However, substantial inter-individual variation of MSR within species resulted in an ongoing methodological controversy, questioning the appropriateness of standard MSR tests for cross-species comparisons. Lack of motivation, in particular, is discussed as one possible cause for false negative results. Here, we compare the spontaneous behavioral response of 47 zoo-housed chimpanzees (Pan troglodytes) to (i) standard body-sized, stationary mirrors and (ii) small, portable hand mirrors. We predicted that the monopolizability and maneuverability of small mirrors increase the chances of identifying MSR across a larger proportion of individuals. Chimpanzees both revealed a substantially higher frequency of general mirror-related behaviors and engaged in significantly more and longer behaviors specifically indicating MSR when provided with small mirrors compared to a large mirror. Handheld mirrors provide a more sensitive measure for MSR within and likely between primate species than the traditional large mirrors, and thereby are a potentially valuable tool for studying self-awareness across species.

Phenomics Approach to Investigate Behavioral Toxicity of Environmental or Occupational Toxicants in Adult Zebrafish (Danio rerio).

Over the last few years, environmental pollution, especially water pollution, has become a serious issue worldwide. Thus, methods that can help us understand the impact and effects of these pollutants, especially on aquatic animals, are needed. Behavioral assessment has emerged as a crucial tool in toxicology and pharmacology because many studies have shown, in multiple animal models, that various pharmacological compounds can alter behavior, with many of the findings being translatable to humans. Moreover, behavior study can also be used as a suitable indicator in the ecotoxicological risk assessment of pollutants. Several model organisms, especially rodent models, have been extensively employed for behavior studies. However, assessments using this model are generally time consuming, expensive, and require extensive facilities for housing experimental animals. Moreover, behavioral studies typically use different measurements and assessment tools, making comparisons difficult. In addition, even though behavioral phenomics has the potential to comprehensively illustrate the toxicities of chemicals, there is only a limited number of studies focusing on animal behavior using such a global approach. Here, we describe a phenomics approach that can be used to investigate the impact of pollutants using zebrafish. The approach consists of several behavioral tests, including response to a novel environment, mirror-reflection image, predator fish, and conspecifics, after exposure to a test chemical. Phenotype fingerprinting, a method for summarizing individual phenotypes based on the results of the behavioral tests, is then conducted to reduce data complexity and display the pattern of each compound on behavioral phenotypes in zebrafish. This approach may be useful to researchers studying the potential adverse effects of different pollutants. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Novel tank test Basic Protocol 2: Shoaling test Basic Protocol 3: Aggression test (mirror biting test) Basic Protocol 4: Social interaction test Basic Protocol 5: Fear response test Basic Protocol 6: PCA and heatmap clustering.

Distortion mapping correction in the AIMS primary mirror testing by a computer-generated hologram

The National Solar Observatory is currently developing the Accurate Infrared Magnetic Field Measurements of the Sun (AIMS). The primary mirror of the AIMS solar telescope is an off-axis parabolic with a diameter of 1 m and with a large off-axis amount of 1 m. Due to the surface figure of the primary mirror under the used state is directly related to image quality of the whole system, a computer-generated hologram (CGH) is carried out to test the primary mirror, and the test results are used to polish the mirror to a higher surface accuracy. However, the fact that the distortion exists in the testing results leads to the failure of a further guide to deterministic optical processing. In this paper, a distortion correction method is proposed, which uses an orthogonal set of vector polynomials to mapping the coordinates of the mirror and the pixels of fringes, and then an interpolation method is adopted to obtain the corrected results. The testing accuracy by using CGH is also verified by an auto-collimate test experiment. According to the distorted corrected results, the root-mean-square of the surface figure is about 1/50λ (λ = 632.8 nm) after polishing.

Automatic Mirror Folding Design Arduino-Based

The rear-view mirror is one of the main devices found in cars. A mirror is a mirror used to see the traffic of a vehicle behind when it is about to veer, stop or change lanes. The purpose of this study was to design a pre-crash performance test of the rearview mirror. That is a system that will automatically perform mirror folding automatically based on the distance of the object in front of it. The system will reduce the risk of broken or scratched due to driver negligence. The research method at a time when the barrier is 30cm (±20cm) away from the front or back of the rearview mirror will read that distance which will then transmit to the Arduino. Arduino will process the data and send data for the speed reduction process by warning that there is an object in front or behind the rearview mirror and when the distance is <30cm from the barrier object, then the Arduino will order to fold the rearview mirror automatically, by activating the servo motor to fold the rear and rearview mirrors. The result of this study was to find out the performance of the GP2Y0A21 distance sensor reading and the performance of the rearview mirror pre-crash system. In this study, the bound variable was the distance measurement of the sensor's reading. The free variable used is the sensor reading metering distance displayed on the LCD (Liquid Crystal Display).

Putting the cart before the horse: claims for mirror self-recognition in horses are unfounded.

The recent article by Baragli, Scopa, Maglieri, and Palagi (Anim Cogn https://doi.org/10.1007/s10071-021-01502-7 , 2021) that claims to demonstrate mirror self-recognition (MSR) in horses is not based on compelling evidence. We identify problems with their experimental procedures, data, and assertion about "demonstrating MSR at group level." Examples of these problems include incomplete experimental design, absence of important control conditions, inappropriate terminology, suboptimal mark application procedures and coding of videos, ambiguity of videos presented as supporting evidence, and inconsistencies in data presentation and interpretation. It is not the case that their study "marks a turning point in the analytical technique of MSR exploration."

Neu1 deficiency induces abnormal emotional behavior in zebrafish

NEU1 sialidase hydrolyzes sialic acids from glycoconjugates in lysosomes. Deficiency of NEU1 causes sialidosis with symptoms including facial dysmorphism, bone dysplasia, and neurodegeneration. However, the effects of NEU1 deficiency on emotional activity have not been explored. Here, we conducted the behavioral analysis using Neu1-knockout zebrafish (Neu1-KO). Neu1-KO zebrafish showed normal swimming similar to wild-type zebrafish (WT), whereas shoaling was decreased and accompanied by greater inter-fish distance than WT zebrafish. The aggression test showed a reduced aggressive behavior in Neu1-KO zebrafish than in WT zebrafish. In the mirror and 3-chambers test, Neu1-KO zebrafish showed more interest toward the opponent in the mirror and multiple unfamiliar zebrafish, respectively, than WT zebrafish. Furthermore, Neu1-KO zebrafish also showed increased interaction with different fish species, whereas WT zebrafish avoided them. In the black–white preference test, Neu1-KO zebrafish showed an abnormal preference for the white region, whereas WT zebrafish preferred the black region. Neu1-KO zebrafish were characterized by a downregulation of the anxiety-related genes of the hypothalamic–pituitary–adrenal axis and upregulation of lamp1a, an activator of lysosomal exocytosis, with their brains accumulating several sphingoglycolipids. This study revealed that Neu1 deficiency caused abnormal emotional behavior in zebrafish, possibly due to neuronal dysfunction induced by lysosomal exocytosis.

Robot passes the mirror test by inner speech

The mirror test is a well-known task in Robotics. The existing strategies are based on kinesthetic-visual matching techniques and manipulate perceptual and motion data. The proposed work attempts to demonstrate that it is possible to implement a robust robotic self-recognition method by the inner speech, i.e. the self-dialogue that enables reasoning on symbolic information. The robot self-talks and conceptually reasons on the symbolic forms of signals, and infers if the robot it sees in the mirror is itself or not. The idea is supported by the existing literature in psychology, where the importance of inner speech in self-reflection and self-concept emergence for solving the mirror test was empirically demonstrated.