Distinct Acute Zones for Visual Stimuli in Different Visual Tasks in Drosophila

The fruit fly Drosophila melanogaster has a sophisticated visual system and exhibits complex visual behaviors. Visual responses, vision processing and higher cognitive processes in Drosophila have been studied extensively. However, little is known about whether the retinal location of visual stimuli can affect fruit fly performance in various visual tasks. We tested the response of wild-type Berlin flies to visual stimuli at several vertical locations. Three paradigms were used in our study: visual operant conditioning, visual object fixation and optomotor response. We observed an acute zone for visual feature memorization in the upper visual field when visual patterns were presented with a black background. However, when a white background was used, the acute zone was in the lower visual field. Similar to visual feature memorization, the best locations for visual object fixation and optomotor response to a single moving stripe were in the lower visual field with a white background and the upper visual field with a black background. The preferred location for the optomotor response to moving gratings was around the equator of the visual field. Our results suggest that different visual processing pathways are involved in different visual tasks and that there is a certain degree of overlap between the pathways for visual feature memorization, visual object fixation and optomotor response.     

Cross-modal recognition of shape from hand to eyes in human newborns

The hypothesis that the ability to coordinate information between tactual and visual modalities is present at birth and dependent on perceptual inherent structures was tested in human newborns. Using an intersensory paired-preference procedure, we showed that newborns can visually recognize the shape of an object that they have previously manipulated with their right hand, out of sight. This is an experimental evidence that newborns can extract shape information in a tactual format and transform it in a visual format before they have had the opportunity to learn from the pairings of visual and tactual experience. This is contrary to a host of theories and models of perceptual learning, both traditional (empiricist philosophers) and modern (connectionist).     

Recognition memory in tree shrew (Tupaia belangeri) after repeated familiarization sessions

Recognition memories are formed during perceptual experience and allow subsequent recognition of previously encountered objects as well as their distinction from novel objects. As a consequence, novel objects are generally explored longer than familiar objects by many species. This novelty preference has been documented in rodents using the novel object recognition (NOR) test, as well is in primates including humans using preferential looking time paradigms. Here, we examine novelty preference using the NOR task in tree shrew, a small animal species that is considered to be an intermediary between rodents and primates. Our paradigm consisted of three phases: arena familiarization, object familiarization sessions with two identical objects in the arena and finally a test session following a 24-h retention period with a familiar and a novel object in the arena. We employed two different object familiarization durations: one and three sessions on consecutive days. After three object familiarization sessions, tree shrews exhibited robust preference for novel objects on the test day. This was accompanied by significant reduction in familiar object exploration time, occurring largely between the first and second day of object familiarization. By contrast, tree shrews did not show a significant preference for the novel object after a one-session object familiarization. Nonetheless, they spent significantly less time exploring the familiar object on the test day compared to the object familiarization day, indicating that they did maintain a memory trace for the familiar object. Our study revealed different time courses for familiar object habituation and emergence of novelty preference, suggesting that novelty preference is dependent on well-consolidated memory of the competing familiar object. Taken together, our results demonstrate robust novelty preference of tree shrews, in general similarity to previous findings in rodents and primates.     

Visual screening of pre-school children.

In an attempt to reduce the incidence of persistent amblyopia and related disorders, routine screening of the visual function of pre-school children has been introduced in Ayrshire, the tests being carried out by orthoptists. A pilot study confirmed the feasibility of the screening. Under the definitive scheme, whose first three months'' results are presented, the children are examined as near as possible to their homes and the average attendance rate has been 86%. Thirty-seven of 442 children were referred to an ophthalmic clinic with suspected abnormalities (only one of which was not confirmed) that had not been picked up by the GP or welfare clinic. It is concluded that visual screening of pre-school children is administratively feasible and welcomed by parents, and that it can detect abnormalities missed by traditional procedures-which according to these results may be more than half of the total.     

Role of chemical and visual cues in food recognition by leatherback posthatchlings (Dermochelys coriacea L)

We raised leatherback posthatchlings in the laboratory for up to 7 weeks to study the role of visual and chemical cues in food recognition and food-seeking behavior. Turtles were reared on a formulated (artificial gelatinous) diet and had no contact with test materials until experiments began. Subjects were presented with visual cues (a plastic jellyfish; white plastic shapes [circle, square, diamond] similar in surface area to the plastic model), chemical cues (homogenates of lion's mane jellyfish, Cyanea capillata; moon jellyfish, Aurelia aurita; and a ctenophore, Ocyropsis sp., introduced through a water filter outflow), and visual and chemical cues presented simultaneously. Visual stimuli evoked an increase in swimming activity, biting, diving, and orientation toward the object. Chemical cues elicited an increase in biting, and orientation into water currents (rheotaxis). When chemical and visual stimuli were combined, turtles ignored currents and oriented toward the visual stimuli. We conclude that both cues are used to search for, and locate, food but that visual cues may be of primary importance. We hypothesize that under natural conditions turtles locate food visually, then, as a consequence of feeding, associate chemical with visual cues. Chemical cues then may function alone as a feeding attractant.     

Perceiving Object Shape from Specular Highlight Deformation,Boundary Contour Deformation,and Active Haptic Manipulation

It is well known that motion facilitates the visual perception of solid object shape, particularly when surface texture or other identifiable features (e.g., corners) are present. Conventional models of structure-from-motion require the presence of texture or identifiable object features in order to recover 3-D structure. Is the facilitation in 3-D shape perception similar in magnitude when surface texture is absent? On any given trial in the current experiments, participants were presented with a single randomly-selected solid object (bell pepper or randomly-shaped “glaven”) for 12 seconds and were required to indicate which of 12 (for bell peppers) or 8 (for glavens) simultaneously visible objects possessed the same shape. The initial single object’s shape was defined either by boundary contours alone (i.e., presented as a silhouette), specular highlights alone, specular highlights combined with boundary contours, or texture. In addition, there was a haptic condition: in this condition, the participants haptically explored with both hands (but could not see) the initial single object for 12 seconds; they then performed the same shape-matching task used in the visual conditions. For both the visual and haptic conditions, motion (rotation in depth or active object manipulation) was present in half of the trials and was not present for the remaining trials. The effect of motion was quantitatively similar for all of the visual and haptic conditions–e.g., the participants’ performance in Experiment 1 was 93.5 percent higher in the motion or active haptic manipulation conditions (when compared to the static conditions). The current results demonstrate that deforming specular highlights or boundary contours facilitate 3-D shape perception as much as the motion of objects that possess texture. The current results also indicate that the improvement with motion that occurs for haptics is similar in magnitude to that which occurs for vision.     

Do infant Japanese macaques (<Emphasis Type="Italic">Macaca fuscata</Emphasis>) categorize objects without specific training?

In the present study, we examined whether infant Japanese macaques categorize objects without any training, using a similar technique also used with human infants (the paired-preference method). During the familiarization phase, subjects were presented twice with two pairs of different objects from one global-level category. During the test phase, they were presented twice with a pair consisting of a novel familiar-category object and a novel global-level category object. The subjects were tested with three global-level categories (animal, furniture, and vehicle). It was found that they showed significant novelty preferences as a whole, indicating that they processed similarities between familiarization objects and novel familiar-category objects. These results suggest that subjects responded distinctively to objects without training, indicating the possibility that infant macaques possess the capacity for categorization.     

The assessment of preschool children's motor skills after familiarization with motor tests

This research study was conducted to establish the influence of familiarization on the information component of movement in a motor task for the assessment of preschool children's motor skills. The sample included 50 children whose mean age was 5.9 years (71.5 months). The experimental group consisted of 27 children who were 5.9 years (71.5 months) old, and the control group consisted of 23 children who were 5.9 years (71.5 months) old. The examinees performed 2 motor tasks, standing long jump (SJ, explosive strength) and standing on 1 leg on a beam "flamingo test" (FT, balance). The experimental group underwent a period of familiarization with the motor task in 3 sessions with 5 trials every 3 days. The results indicate statistically significant differences in the final testing between both groups of examinees; the experimental group mean was 112.73 cm, and the control group mean was 100.62 in the SJ test (p = 0.00), and the experimental group mean was 27.10 seconds and the control group mean was 15.01 seconds in the FT (for balance) (p = 0.00). The results obtained in this research indicate that children significantly improved the results in the motor test of strength and balance, being influenced by familiarization. It was confirmed that it was necessary for preschool children to be familiar with the test and it is not justified to use testing and assessment protocols and standards for adults. Physical educators and coaches, when testing preschool children, should introduce children to tests to obtain the best result.     

Opposite Distortions in Interval Timing Perception for Visual and Auditory Stimuli with Temporal Modulations

When an object is presented visually and moves or flickers, the perception of its duration tends to be overestimated. Such an overestimation is called time dilation. Perceived time can also be distorted when a stimulus is presented aurally as an auditory flutter, but the mechanisms and their relationship to visual processing remains unclear. In the present study, we measured interval timing perception while modulating the temporal characteristics of visual and auditory stimuli, and investigated whether the interval times of visually and aurally presented objects shared a common mechanism. In these experiments, participants compared the durations of flickering or fluttering stimuli to standard stimuli, which were presented continuously. Perceived durations for auditory flutters were underestimated, while perceived durations of visual flickers were overestimated. When auditory flutters and visual flickers were presented simultaneously, these distortion effects were cancelled out. When auditory flutters were presented with a constantly presented visual stimulus, the interval timing perception of the visual stimulus was affected by the auditory flutters. These results indicate that interval timing perception is governed by independent mechanisms for visual and auditory processing, and that there are some interactions between the two processing systems.     

Sensory modality and time perception in children and adults

This experiment investigated the effect of signal modality on time perception in 5- and 8-year-old children as well as young adults using a duration bisection task in which auditory and visual signals were presented in the same test session and shared common anchor durations. Durations were judged shorter for visual than for auditory signals by all age groups. However, the magnitude of this modality difference was larger in the children than in the adults. Sensitivity to time was also observed to increase with age for both modalities. Taken together, these two observations suggest that the greater modality effect on duration judgments for the children, for whom attentional abilities are considered limited, is the result of visual signals requiring more attentional resources than are needed for the processing of auditory signals. Within the framework of the information-processing model of Scalar Timing Theory, these effects are consistent with a developmental difference in the operation of the "attentional switch" used to transfer pulses from the pacemaker into the accumulator. Specifically, although timing is more automatic for auditory than visual signals in both children and young adults, children have greater difficulty in keeping the switch in the closed state during the timing of visual signals.     

Food imprinting, new evidence from the cuttlefish Sepia officinalis

Imprinting provides precocial offspring with an efficient means to optimize their subsequent behaviours. We discovered food imprinting using a sophisticated invertebrate model: the cuttlefish. We showed that early juveniles preferred the prey to which they have been visually familiarized, when the amount of information was sufficient and only if such familiarization occurred during a short sensitive period. We also demonstrated that the effects of visual food imprinting overcame those of the first food ingested. Our study shows that visual imprinting is a critical process in animals, surpassing more direct reward experiences that occur outside the critical exposure period.     

Am I seeing my hand? Visual appearance and knowledge of controllability both contribute to the visual capture of a person's own body

When confronted with complex visual scenes in daily life, how do we know which visual information represents our own hand? We investigated the cues used to assign visual information to one''s own hand. Wrist tendon vibration elicits an illusory sensation of wrist movement. The intensity of this illusion attenuates when the actual motionless hand is visually presented. Testing what kind of visual stimuli attenuate this illusion will elucidate factors contributing to visual detection of one''s own hand. The illusion was reduced when a stationary object was shown, but only when participants knew it was controllable with their hands. In contrast, the visual image of their own hand attenuated the illusion even when participants knew that it was not controllable. We suggest that long-term knowledge about the appearance of the body and short-term knowledge about controllability of a visual object are combined to robustly extract our own body from a visual scene.     

Use of tomicid in prophylaxis of respiratory streptococcal infection in the organized groups of children of pre-school age

The results of the approbation of the use of Tomicid for the prophylaxis of scarlet fever and other manifestations of streptococcal infection in an organized group of children of pre-school age are presented. The pronounced prophylactic effect of Tomicid, manifested by a reliable decrease of group A streptococcal carrier state, as well as in a decrease in morbidity in respiratory streptococcal infection among children in the test group in comparison with those in the control one. The simplicity of the use of the preparation (as throat gargle for 5 days) makes it possible to regard this preparation as a promising remedy for the urgent prophylaxis of scarlet fever.     

Tapetoretinal Degeneration in Childhood Presenting as a Disturbance of Behaviour

Four children presented at the age of 6 years with progressive disturbances of behaviour due to increasing visual handicap. In three of them routine ophthalmological examination was carried out in the early stages, but no objective evidence of eye disease was found. The severity and nature of the visual defect and its causal relationship to the behaviour disorder went unrecognized for periods ranging from 18 to 30 months. Eventually the development of retinal changes enabled a diagnosis of tapetoretinal degeneration to be made which was confirmed by the finding of extinction of the electroretinographic response. Transfer of the children to schools for the visually handicapped resulted in improvement in their behaviour disorder.Electroretinography is of great importance in the early diagnosis of juvenile tapetoretinal degeneration.     

Associatieve visuele agnosie. De minder zichtbare gevolgen van een herseninfarct

After a cerebral infarction, some patients acutely demonstrate contralateral hemiplegia, or aphasia. Those are the obvious symptoms of a cerebral infarction. However, less visible but burdensome consequences may go unnoticed without closer investigation. The importance of a thorough clinical examination is exemplified by a single case study of a 72-year-old, right-handed male. Two years before he had suffered from an ischemic stroke in the territory of the left posterior cerebral artery, with right homonymous hemianopia and global alexia (i.e., impairment in letter recognition and profound impairment of reading) without agraphia. Naming was impaired on visual presentation (20%-39% correct), but improved significantly after tactile presentation (87% correct) or verbal definition (89%). Pre-semantic visual processing was normal (correct matching of different views of the same object), as was his access to structural knowledge from vision (he reliably distinguished real objects from non-objects). On a colour decision task he reliably indicated which of two items was coloured correctly. Though he was unable to mime how visually presented objects were used, he more reliably matched pictures of objects with pictures of a mime artist gesturing the use of the object. He obtained normal scores on word definition (WAIS-III), synonym judgment and word-picture matching tasks with perceptual and semantic distractors. He however failed when he had to match physically dissimilar specimens of the same object or when he had to decide which two of five objects were related associatively (Pyramids and Palm Trees Test). The patient thus showed a striking contrast in his intact ability to access knowledge of object shape or colour from vision and impaired functional and associative knowledge. As a result, he could not access a complete semantic representation, required for activating phonological representations to name visually presented objects. The pattern of impairments and preserved abilities is considered to be a specific difficulty to access a full semantic representation from an intact structural representation of visually presented objects, i.e., a form of visual object agnosia.     

A Method to Quantify Visual Information Processing in Children Using Eye Tracking

Visual problems that occur early in life can have major impact on a child''s development. Without verbal communication and only based on observational methods, it is difficult to make a quantitative assessment of a child''s visual problems. This limits accurate diagnostics in children under the age of 4 years and in children with intellectual disabilities. Here we describe a quantitative method that overcomes these problems. The method uses a remote eye tracker and a four choice preferential looking paradigm to measure eye movement responses to different visual stimuli. The child sits without head support in front of a monitor with integrated infrared cameras. In one of four monitor quadrants a visual stimulus is presented. Each stimulus has a specific visual modality with respect to the background, e.g., form, motion, contrast or color. From the reflexive eye movement responses to these specific visual modalities, output parameters such as reaction times, fixation accuracy and fixation duration are calculated to quantify a child''s viewing behavior. With this approach, the quality of visual information processing can be assessed without the use of communication. By comparing results with reference values obtained in typically developing children from 0-12 years, the method provides a characterization of visual information processing in visually impaired children. The quantitative information provided by this method can be advantageous for the field of clinical visual assessment and rehabilitation in multiple ways. The parameter values provide a good basis to: (i) characterize early visual capacities and consequently to enable early interventions; (ii) compare risk groups and follow visual development over time; and (iii), construct an individual visual profile for each child.     

Characteristics of invariant recognition of visual objects in preschool children with typical and atypical development

The invariant recognition ability of five- to six-year-old children with typical and atypical patterns of development in terms of the shape of visual images varying in color, size, and location has been studied. It has been shown that the typically developing children of this age are able to identify the invariant form of a visual object regardless of any changes in its color, size, or location. The children with neurodevelopmental disorders have difficulties with identifying the shape of a visual object when its location among a large number of figures is changed. The children with early infantile autism exhibit different degrees of visual perceptual deficit. The children with the milder forms of autistic disorders have difficulties only with recognizing the shape of an image when its location is changed; the children with more severe forms of disorders showed a serious impairment of invariant recognition regardless of image color, size, and location.     

Audiovisual integration of letters in the human brain

Letters of the alphabet have auditory (phonemic) and visual (graphemic) qualities. To investigate the neural representations of such audiovisual objects, we recorded neuromagnetic cortical responses to auditorily, visually, and audiovisually presented single letters. The auditory and visual brain activations first converged around 225 ms after stimulus onset and then interacted predominantly in the right temporo-occipito-parietal junction (280345 ms) and the left (380-540 ms) and right (450-535 ms) superior temporal sulci. These multisensory brain areas, playing a role in audiovisual integration of phonemes and graphemes, participate in the neural network supporting the supramodal concept of a "letter." The dynamics of these functions bring new insight into the interplay between sensory and association cortices during object recognition.     

Seeing Touches Early in Life

The sense of touch provides fundamental information about the surrounding world, and feedback about our own actions. Although touch is very important during the earliest stages of life, to date no study has investigated infants’ abilities to process visual stimuli implying touch. This study explores the developmental origins of the ability to visually recognize touching gestures involving others. Looking times and orienting responses were measured in a visual preference task, in which participants were simultaneously presented with two videos depicting a touching and a no-touching gesture involving human body parts (face, hand) and/or an object (spoon). In Experiment 1, 2-day-old newborns and 3-month-old infants viewed two videos: in one video a moving hand touched a static face, in the other the moving hand stopped before touching it. Results showed that only 3-month-olds, but not newborns, differentiated the touching from the no-touching gesture, displaying a preference for the former over the latter. To test whether newborns could manifest a preferential visual response when the touched body part is different from the face, in Experiment 2 newborns were presented with touching/no-touching gestures in which a hand or an inanimate object—i.e., a spoon- moved towards a static hand. Newborns were able to discriminate a hand-to-hand touching gesture, but they did not manifest any preference for the object-to-hand touch. The present findings speak in favour of an early ability to visually recognize touching gestures involving the interaction between human body parts.     

Cognitive control in recognition of an emotionally negative face in five- to ten-year-old children

We used the experimental model of cognitive visual set, designed by D.N. Uznadze, to study the influence of previous experience on emotional face expression recognition in pre-school (6.1 ± 0.3 years) and elementary school (10.5 ± 0.1 years) children. Our results suggest that the ability to form a cognitive set to an angry face expression develops in ontogenesis in strong concordance with functional maturation of prefrontal cortex that takes place at the age of approximately 10 years. At this age children display almost the same level of set plasticity and a similar kind of erroneous perceptions during set actualization as grown-ups. Children of younger age (6.1 ± 0.3 years) display more perceverative erroneous perceptions, or assimilative illusions (probably of a priming origin), than the above mentioned groups. We consider this to be a result of a more strong influence of previous experience in their case.