Objective: Classification of voices into types depends on several factors: physiological - the size of the laryngeal and vocal tracts; acoustic-musically acceptable vocal range; position of formants; and properties of timbre. The aim of the study is to verify whether a group of experienced voice pedagogues and singers can determine the vocal type of the artist based on listening to a part of the aria better than a group of musicians can, and to determine what acoustic properties of the recordings are linked with the perceptual results of their evaluation.Methods: Freely available recordings of 11 females of different vocal categories of Rossini's aria "Una voce poco fa" from the opera Il Barbiere di Seviglia were selected for listening tests performed on examples of recitatives and coloraturas. Seven voice teachers (experienced group) and seven musicians non-teachers (laypeople group) evaluated the properties of the vocal category, timbre (dark-bright), resonance, vowel placement, suitability of vibrato, aesthetic impression, and voice flexibility.Results: The results showed a significantly higher inter-judge reliability in the experienced group. The highest reliability was achieved in timbre and vocal category evaluation, the least consistent was the evaluation of resonance. Factor analysis of the assessment variability showed dependent ratings of the vocal category, brightness and vowel placement for both groups in recitative. The experienced group similarly evaluated the brightness and the vocal category in coloratura. Assessment of the vocal category correlated with the reported categories of singers only in the experienced group. The categories mezzo-soprano and soprano were differentiated by spectral levels (based on FFT analysis of whole stimuli) in the 3.5-4.1 kHz spectral band in the recitative and in the 1.3-2.1 kHz and around 2.5 kHz bands in coloratura, and by the position of the local minimum after the fifth maximum for both kinds of stimuli.Conclusions: By means of correlation with ratings by experienced listeners, it is demonstrated that the voice category is mainly connected with the levels of specific spectral peaks, while brightness is correlated with the frequency positions of spectral maxima.

• MeSH
• Acoustics MeSH
• Voice Quality * MeSH
• Humans MeSH
• Judgment MeSH
• Observer Variation MeSH
• Sex Factors MeSH
• Auditory Perception * MeSH
• Singing * MeSH
• Sound Spectrography MeSH
• Check Tag
• Humans MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Comparative Study MeSH

Humans perceive snakes as threatening stimuli, resulting in fast emotional and behavioral responses. However, snake species differ in their true level of danger and are highly variable in appearance despite the uniform legless form. Different snakes may evoke fear or disgust in humans, or even both emotions simultaneously. We designed three-step-selection experiments to identify prototypical snake species evoking exclusively fear or disgust. First, two independent groups of respondents evaluated 45 images covering most of the natural variability of snakes and rated responses to either perceived fear (n = 175) or disgust (n = 167). Snakes rated as the most fear-evoking were from the family Viperidae (Crotalinae, Viperinae, and Azemiopinae), while the ones rated as the most disgusting were from the group of blind snakes called Typhlopoidea (Xenotyphlopinae, Typhlopinae, and Anomalepidinae). We then identified the specific traits contributing to the perception of fear (large body size, expressive scales with contrasting patterns, and bright coloration) and disgust (thin body, smooth texture, small eyes, and dull coloration). Second, to create stimuli evoking a discrete emotional response, we developed a picture set consisting of 40 snakes with exclusively fear-eliciting and 40 snakes with disgust-eliciting features. Another set of respondents (n = 172) sorted the set, once according to perceived fear and the second time according to perceived disgust. The results showed that the fear-evoking and disgust-evoking snakes fit mainly into their respective groups. Third, we randomly selected 20 species (10 fear-evoking and 10 disgust-evoking) out of the previous set and had them professionally illustrated. A new set of subjects (n = 104) sorted these snakes and confirmed that the illustrated snakes evoked the same discrete emotions as their photographic counterparts. These illustrations are included in the study and may be freely used as a standardized assessment tool when investigating the role of fear and disgust in human emotional response to snakes.

• Publication type
• Journal Article MeSH

Publikace se zabývá procesy tvořící barevný vjem. Věnuje pozornost fotometrii a světlu, teoriím barevného vidění, vzniku a šíření neuronových signálů do mozku. Dále se zabývá kolorimetrií, kolorimetrickými přístroji a metody měření. Učebnice pro odborníky, postgraduální studenty polygrafie i laiky.; Jaké procesy generují náš barevný vjem? Jak lze exaktně definovat a měřit barvu? Na tyto a mnoho dalších otázek odpovídá tato kniha. V první části nazvané Barevné vidění jsou uvedeny procesy tvořící barevný vjem. Mimo standardní kapitoly zabývající se fotometrií a světlem je pozornost věnována teoriím barevného vidění, vzniku a šíření neuronových signálů do mozku. Ve druhé části knihy s označením Kolorimetrie jsou uvedeny základní matematické vztahy, pomocí nichž lze definovat a vytvořit barvové prostory dle norem CIE. Publikaci završuje kapitola o kolorimetrických přístrojích a metodách měření. Tato kniha vznikla na základě mnoholetých zkušeností autora získaných při řešení úloh kolorimetrie a výuce těchto předmětů na vysoké škole. Je výjimečná tím, že její obsah je konceptuálně ukotven ve více vědních disciplínách. Vyznačuje se vysokou metodologickou úrovní a náročností zpracování. Osloví nejen odbornou veřejnost, ale i čtenáře zabývající se tvorbou a reprodukcí barevného obrazu.

• MeSH
• Colorimetry methods   MeSH
• Ocular Physiological Phenomena MeSH
• Light MeSH
• Color Vision MeSH
• Color Perception MeSH
• Publication type
• Monograph MeSH
• Popular Work MeSH
• Textbook MeSH

• Conspectus
• Optika
• Učební osnovy. Vyučovací předměty. Učebnice
• NML Fields
• fyzika, biofyzika
• oftalmologie

The role of rodent hippocampus has been intensively studied in different cognitive tasks. However, its role in discrimination of objects remains controversial due to conflicting findings. We tested whether the number and type of features available for the identification of objects might affect the strategy (hippocampal-independent vs. hippocampal-dependent) that rats adopt to solve object discrimination tasks. We trained rats to discriminate 2D visual objects presented on a computer screen. The objects were defined either by their shape only or by multiple-features (a combination of filling pattern and brightness in addition to the shape). Our data showed that objects displayed as simple geometric shapes are not discriminated by trained rats after their hippocampi had been bilaterally inactivated by the GABAA-agonist muscimol. On the other hand, objects containing a specific combination of non-geometric features in addition to the shape are discriminated even without the hippocampus. Our results suggest that the involvement of the hippocampus in visual object discrimination depends on the abundance of object's features.

• MeSH
• GABA-A Receptor Agonists pharmacology   MeSH
• Behavior, Animal drug effects   physiology   MeSH
• Discrimination Learning drug effects   physiology   MeSH
• Generalization, Psychological drug effects   physiology   MeSH
• Hippocampus drug effects   physiology   MeSH
• Rats MeSH
• Muscimol pharmacology   MeSH
• Conditioning, Operant drug effects   physiology   MeSH
• Rats, Long-Evans MeSH
• Pattern Recognition, Visual drug effects   physiology   MeSH
• Form Perception drug effects   physiology   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

UNLABELLED: Single cases may lead to unexpected hypotheses in psychology. We retrospectively analyzed single case studies that suggested organizational principles along the early visual pathway, which have remained unanswered until now. FIRST CASE: In spite of the inhomogeneity of sensitivity, paradoxically the visual field on the subjective level appears to be homogeneous; constancy of brightness of supra-threshold stimuli throughout the visual field is claimed to be responsible for homogeneity; specific summation properties of retinal ganglion cells are hypothesized to guarantee this effect. SECOND CASE: With a brain-injured patient having suffered a partial visual field loss it can be shown that color induction is a retinal phenomenon; lateral inhibitory processes at the level of amacrine cells are hypothesized as neural network. Third case: In a patient having suffered a bilateral occipital lobe infarction, some functional recovery has been demonstrated; divergence and convergence of projection in the ascending neural pathway are suggested as a structural basis for recovery. Slowed down binocular rivalry discloses a sequential mechanism in the construction of a visual percept. Fourth case: The pre-wired projection of the retina to the visual cortex in spite of a severe squint of one eye is confirmed, but paradoxically some local neuroplasticity is also suggested. Fifth case: Using habituation of local sensitivity in the visual field and its resetting by interhemispheric interactions as an experimental paradigm, it is suggested that spatial attention is controlled at the midbrain level. Sixth case: Observations on residual vision or "blindsight" support the hypothesis that the visual cortex is the one and only structure responsible for visual perception on a conscious level. The unifying principle of these retrospective analyses is that subjective visual phenomena can lead to unexpected but testable hypotheses of neural processing on the structural and functional level in the early visual pathway.

• MeSH
• Humans MeSH
• Geniculate Bodies physiology   MeSH
• Brain Infarction physiopathology   MeSH
• Brain Injuries physiopathology   MeSH
• Attention physiology   MeSH
• Retina physiology   MeSH
• Retrospective Studies MeSH
• Blindness physiopathology   MeSH
• Photic Stimulation MeSH
• Color Perception MeSH
• Visual Fields * MeSH
• Visual Pathways physiology   MeSH
• Visual Cortex physiology   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Case Reports MeSH

Certain light environments may hinder egg discrimination by hosts of foreign eggs, which could in some circumstances lead to the acceptance of non-mimetic eggs by hosts. We measured light parameters at red bishop (Euplectes orix) nests and used a model of avian visual processing to quantify the detectability of eggs in the light environment in which they are perceived. We found that the overall amount of light was very variable between red bishop nests and always sufficient for colour discrimination. A model of avian visual processing revealed that nest luminosity had no influence on host responses towards eggs which were painted dark brown. Dark eggs do not appear to be cryptic in red bishop nests and can be distinguished with ease, whereas natural red bishop eggs are usually accepted, despite the domed structure of the nest. We found little variation in both chromatic and achromatic contrasts between host and artificial eggs, indicating that there was very little variation in the light quality inside nests. We suggest that nest luminosity is likely to play a role in egg recognition in situations when light reaches threshold values for colour discrimination, i.e. in scotopic as opposed to photopic vision. Rejection rates for dark eggs were higher than for bright (conspecific) foreign eggs. More investigation of domed nest-building species is required, as this type of nest appears to have a highly variable light environment, dependent on both nest structure and habitat.

• MeSH
• Color MeSH
• Species Specificity MeSH
• Ecosystem MeSH
• Nesting Behavior physiology   MeSH
• Host-Parasite Interactions physiology   MeSH
• Ovum * MeSH
• Parasites MeSH
• Passeriformes physiology   MeSH
• Recognition, Psychology MeSH
• Light * MeSH
• Egg Shell chemistry   MeSH
• Visual Perception physiology   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH

OBJECTIVES/HYPOTHESIS: Listeners often describe the voices of solo child singers as being "pure" or "clear"; these terms would suggest that the voice is not only pleasant but also clearly audible. The audibility or clarity could be attributed to the presence of high-frequency partials in the sound: a "brightness" or "ring." This article aims to investigate spectrally the acoustic nature of this ring phenomenon in children's solo voices, and in particular, relating it to their "nonring" production. Additionally, this is set in the context of establishing to what extent, if any, the spectral characteristics of ring are shared with those of the singer's formant cluster associated with professional adult opera singers in the 2.5-3.5kHz region. METHODS: A group of child solo singers, acknowledged as outstanding by a singing teacher who specializes in teaching professional child singers, were recorded in a major UK concert hall performing Come unto him, all ye that labour, from the aria He shall feed his flock from The Messiah by GF Handel. Their singing was accompanied by a recording of a piano played through in-ear headphones. Sound pressure recordings were made from well within the critical distance in the hall. The singers were observed to produce notes with and without ring, and these recordings were analyzed in the frequency domain to investigate their spectra. RESULTS: The results indicate that there is evidence to suggest that ring in child solo singers is carried in two areas of the output spectrum: first in the singer's formant cluster region, centered around 4kHz, which is more than 1000Hz higher than what is observed in adults; and second in the region around 7.5-11kHz where a significant strengthening of harmonic presence is observed. A perceptual test has been carried out demonstrating that 94% of 62 listeners label a synthesized version of the calculated overall average ring spectrum for all subjects as having ring when compared with a synthesized version of the calculated overall average nonring spectrum. CONCLUSIONS: The notion of ring in the child solo voice manifests itself not only with spectral features in common with the projection peak found in adult singers but also in a higher frequency region. It is suggested that the formant cluster at around 4kHz is the children's equivalent of the singers' formant cluster; the frequency is higher than in the adult, most likely due to the smaller dimensions of the epilaryngeal tube. The frequency cluster observed as a strong peak at about 7.5-11kHz, when added to the children's singers' formant cluster, may be the key to cueing the notion of ring in the child solo voice.

• MeSH
• Acoustics MeSH
• Child MeSH
• Voice Quality * MeSH
• Humans MeSH
• Adolescent MeSH
• Auditory Perception * MeSH
• Pressure MeSH
• Age Factors MeSH
• Singing * MeSH
• Sound Spectrography MeSH
• Check Tag
• Child MeSH
• Humans MeSH
• Adolescent MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

• Keywords
• enioanatomie,
• MeSH
• Anatomy, Cross-Sectional MeSH
• Anatomy MeSH
• Mind-Body Relations, Metaphysical MeSH
• Parapsychology MeSH
• Energy Transfer MeSH
• Visible Human Projects MeSH
• Publication type
• Monograph MeSH

• Conspectus
• Anatomie člověka a srovnávací anatomie
• NML Fields
• anatomie

In earlier experiments we have demonstrated that macaque monkeys (Macaca mulatta) are able to use abstract visual stimuli presented on a computer screen to make spatial choices in the real environment. In those experiments a touch board ("response space") was directly connected to the computer screen ("virtual space"). The goal of the present experiment was to find out whether macaque monkeys are able: (1) To make spatial choices in a response space which is completely separated from the screen where the stimuli (designed as representation of the response space) are presented. (2) To make spatial choices based on visual stimuli representing the configuration of the response space which are rotated with respect to this response space. The monkeys were trained to choose one of the nine "touch holes" on a transparent touch panel situated beside a computer monitor on which the visual stimuli were presented. The visual stimuli were designed as an abstract representation of the response space: the rewarded position was shown as a bright circle situated at a certain position in the rectangle representing the contours of the touch panel. At first, the monkeys were trained with non-rotated spatial stimuli. After this initial training, the visual stimuli were gradually rotated by 20 degrees in each step. In the last phase, the stimulus was suddenly rotated in the opposite direction by 60 degrees in one step. The results of the experiment suggest that the monkeys are able to use successfully abstract stimuli from one spatial frame for spatial choices in another frame. Effective use of the stimuli after their rotation suggested that the monkeys perceived the stimuli as a representation of the configuration of the touch holes in the real space, not only as different geometrical patterns without configuration information.

• MeSH
• Discrimination Learning physiology   MeSH
• Touch physiology   MeSH
• Macaca mulatta MeSH
• Conditioning, Operant physiology   MeSH
• Orientation physiology   MeSH
• Reaction Time physiology   MeSH
• Rotation MeSH
• Pattern Recognition, Visual physiology   MeSH
• Photic Stimulation methods   MeSH
• Space Perception physiology   MeSH
• Form Perception physiology   MeSH
• Choice Behavior physiology   MeSH
• Visual Perception physiology   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Animals MeSH

• Keywords
• Slovníky encyklopedické,
• MeSH
• Encyclopedias as Topic MeSH