Two same-different discrimination experiments were performed for click patterns having a total duration of about 4 sec and interclick intervals of n x 250 msec, with n a random integer. In Experiment 1, the influence of the physical click group structure on discrimination performance was investigated. In Experiment 2, the ...

PURPOSE: To investigate the controversial origin of the foveal granular pattern at the center of the entoptic Purkinje vessel shadows. Both phenomena may be vividly elicited by oscillating a focused spot of light across the scleral surface of the eye in a circumferential direction. METHODS: The site and pattern of ...

Recent advances have been made in the understanding of the cellular and molecular mechanisms involved in the formation and patterning of the neural plate of vertebrate embryos. Both planar and vertical signaling pathways appear to be involved in the neural induction and axial patterning of the neural plate. The neural ...

We study the possibility of a metrical readout of velocity from an ensemble of Reichardt correlators. We show that with a suitable choice of spatial and temporal prefiltering of the correlator input it is possible to devise reliable (nonaliasing) velocity-tuned Reichardt detectors. However, because of the well-known covariance of spatial ...

Tonal patterns were delivered to 17 subjects instructed to read a self-selected book and to ignore the auditory stimuli. The standard pattern contained eight 50-ms segments differing in frequency. Infrequent changes of single segments within the pattern elicited negative modulations of the event-related brain potentials (ERPs) as compared with the ...

Musically trained and untrained subjects (N = 30) were asked to synchronize their finger tapping with stimuli in auditory patterns. Each pattern comprised six successive tonal stimuli of the same duration, the first of which was accented by a different frequency. The duration of inter-stimulus onset intervals (ISIs) gradually increased ...

Pattern electroretinograms were studied in response to stripe patterns of different spatial frequencies and intensities in the pattern-onset and reversal mode by means of a scanning laser ophthalmoscope and a mechanical mirror system (maxwellian view). The stimulus conditions in both procedures were as close as possible: 31 degrees square field, ...

We tested the hypothesis that ultraviolet photoreception contributes to prey search in small juvenile rainbow trout (Oncorhynchus mykiss) and pumpkinseed sunfish (Lepomis gibbosus) while foraging on Daphnia pulex. Small individuals of these species are ultraviolet-photosensitive zooplanktivores. For both species, prey pursuit distances and angles were larger under full-spectrum illumination than ...

The effect of five dental investing techniques, three angles formed between adjoining internal pattern surfaces, and the use of a surface tension-reducing agent on air-bubble entrapment during investing were assessed. One investing technique, which mechanically mixed the investment under vacuum, invested the pattern without vacuum, then subjected the setting investment ...

The extent to which auditory, tactile, and visual perceptual representations are similar, particularly when dealing with speech and speech-like stimuli, was investigated. It was found that comparisons between auditory and tactile patterns were easier to perform than were similar comparisons between auditory and visual stimuli. This was true across a ...

The phenomenon of visual occlusion has frequently been studied by means of two-dimensional line drawings. These drawings may elicit various interpretations. Sometimes a mosaic of shapes is seen, sometimes a shape that partly occludes another shape. In the latter case, observers often have a clear idea about the form of ...

This paper reports experimental data and results of network simulations in a project on symmetry detection in small 6 x 6 binary patterns. Patterns were symmetrical about the vertical, horizontal, positive-oblique, or negative-oblique axis, and were viewed on a computer screen. Encouraged to react quickly and accurately, subjects indicated axis ...

Distinctive patterns of premature heart beats are frequently observed in clinical data, yet transitions from one pattern to another often appear to occur unpredictably. In this study we investigate the origins of this apparent lack of long-term order by processing the time intervals between successive R wave features of the ...

The perception of continuously repeating auditory patterns by European starlings was explored in seven experiments. In Experiment 1, 4 starlings learned to discriminate between two continuously repeating, eight-element, auditory patterns. Each eight-element pattern was constructed from different temporal organizations of two elements differing in timbre. In Experiments 2-7, the repeating ...

The transparency phenomenon, which arises when a radial and a rotational motion pattern are spatially superimposed, suggests that these motion patterns are processed independently. Indeed, for unrestricted stimulus durations, observers could identify the rotational pattern as clockwise or counterclockwise, and the radial pattern as expansion or contraction, even under uncertainty. ...

A tactile pattern on the skin generally comes to be recognised from its function within action. What is perceived tactually and may generate a textural or geometrical sensation is therefore a set of dynamic characteristics that can be extracted by mechanoreceptors and central neural processing from the physics of the ...

It is possible to modify the mathematical patterns of projection geometry to reshape the skull in cranio-facial surgery. The technique of the 'gore-pattern' in accordance with the Hendel procedure changes the shape of individual sections of the skull by changing their radius of curvature. This technique was well known to ...

The maximum displacement for the detection of apparent motion (Dmax) is measured using stimuli made up of Gabor function micro-patterns randomly distributed across the stimulus field. Previous studies using high densities of micro-patterns have demonstrated Dmax to be dependent on the spatial frequency content of the stimulus and not the ...

For the past 80 years, the energy released in great strike-slip and thrust earthquakes has occurred in alternating cycles of 20 to 30 years. This pattern suggests that a global transfer mechanism from poloidal to toroidal components of tectonic plate motions is operating on time scales of several decades. The ...

Blaschko's lines are the acknowledged markers which represent the patterns of systematized naevi. Their interpretation has remained mysterious, because certain special features which they exhibit are impossible to reconcile with any known anatomical system in the human body. It is proposed that by changing one's views on the nature and ...

We describe the geographic variation patterns of six dermatoglyphic traits from 144 samples in Eurasia. The methods of analysis include computation of interpolated surfaces, one-dimensional and directional correlograms, correlations between all pairs of surfaces, and distances between correlograms. There are at least two, probably three, distinct and significant patterns of ...

This study tested whether leadership instability--a systemic pattern of frequent succession in the top management position of an organization--was associated with sociopolitical structures that define the relationship between the board and chief executive officer (CEO), controlling for temporal patterns of the organizational life-cycle stage. In organizations that are not profit ...

In a paradigm for which 2 distinct patterns are perceived for the same stimulus, perceptual hysteresis (persistence of a percept despite parameter change to values favoring the alternative pattern) and temporal stability (persistence despite intrinsic propensities toward spontaneous change) are interdependent. Greater persistence during parameter change reduces temporal stability, slowing ...

Acute angles and long lines are more complex than obtuse angles and short lines. This source of complexity is called metrical information, for which a measure was proposed by Leeuwenberg (1982). According to this measure, the metrical information of a static pattern is specified as the sum of the mechanical ...

Does the global precedence effect depend on the goodness of the global form and low spatial frequencies? In Experiments 1 and 2, under a variety of attentional and task conditions, a global advantage in response time (RT) occurred in "good," many-element compound patterns but not in "poor," few-element patterns (unless ...

Pattern discrimination in the presence of distractor patterns is improved when the stimulus display is preceded by a precue designating the location of the target pattern. Experiments were conducted to determine how big an improvement the precue produced. The specific question of whether the observer is able to process selectively ...

Visual system responses (visual evoked potentials) to flash (FVEP) and pattern reversal (PRVEP) stimuli were recorded in mice. Two strains were used: black C57BL/6J mice and agouti B6CBAF1/J mice (first generation offspring of C57BL/6J females and CBA/J males.) Subjects were sedated with ketamine and xylazine. Flash rate (FVEP) and stimulus ...

Two competing models of the effects of pattern element proximity, masking, and perceptual integration on the discriminability of spatiotemporal vibrotactile patterns are compared. Kirman's 'integration hypothesis' predicts that pattern perception is facilitated by a process of perceptual integration which requires that pattern elements be presented in close spatial and temporal ...

Two experiments were carried out to investigate the perception of complex auditory-spatial patterns. Subjects were asked to identify alphanumeric characters whose patterns could be outlined acoustically through the sequential activation of specific units in a speaker array. Signal bandwidths were varied systematically in both experiments. Signals in experiment 1 had ...

Musical tuning perception in infancy and adulthood was explored in three experiments. In Experiment 1, Western adults were tested in detection of randomly located mistunings in a melody based on musical interval patterns from native and nonnative musical scales. Subjects performed better in a Western major scale context than in ...

Bees were trained to discriminate ring-patterns which varied in number of rings and in size. Transfer-tests revealed size discrimination to be largely independent of pattern type and vice versa. A multidimensional scaling procedure, using Minkowski metrics as models, was applied in order to determine the bee's "perceptual metric". The city-block ...

Binocular cyclorotatory (torsional) eye movements in response to visual patterns, which oscillated sinusoidally in the frontal plane, were recorded with scleral induction coils in human subjects. Conjugate cycloversion and disjunctive cyclovergence were directly compared by in-phase and out-of-phase oscillation of the same pattern. Stimulus motion had a frequency of 0.2 ...

Spatial patterns are described and analysed for the 84 most common surnames in England and Wales, as well as 16 others selected for various reasons. At least three-quarters of the surname frequencies show spatial structure and are heterogeneous over the area of study. While they do not exhibit clines extending ...

Pattern reversals with a ramp-like temporal course evoke transient pattern electroretinograms (PERG) that are delayed and attenuated in comparison with responses evoked by a step-like course (abrupt pattern reversals). This delay depends on the reversal time and probably represents a measure for temporal characteristics of the activated retinal structures. A ...

Leaf primordia, first visible as small bumps, are produced in a cyclical pattern at the edges of the shoot apex, a smooth region at the top of the stem. Their formation is a biomechanical process. This review first considers hypothetical construction mechanisms and then summarizes research that provides information about ...

A study was performed to elucidate how different impulse frequencies and impulse patterns in cutaneous nociceptive fibres influence the subjective magnitude of pain. Groups of nociceptive A delta and C fibres were co-activated by electrical intraneural stimulation at constant intensity in cutaneous fascicles of the peroneal nerve in healthy human ...

We have designed and implemented a Motorola 68000 microprocessor-based pattern generator system (PGS) that uses a color video display terminal (VDT) to provide light stimuli to the intact vertebrate retina. This communication is intended for those who are considering acquisition of a commercial retinal stimulator or those who are custom ...

Pigeonite-plagioclase gabbros that occur as clasts in mesosiderites (brecciated stony-iron meteorites) show extreme fractionations of the rare-earth elements (REEs) with larger positive europium anomalies than any previously known for igneous rocks from the Earth, moon, or meteorite parent bodies and greater depletions of light REEs relative to heavy REEs than ...

In this paper some qualitative aspects of centre-surround interaction produced by transient surround stimulation are investigated, employing a new design of quantitative layer-by-layer perimetry. Using a rotating windmill pattern, a transient response, believed to be organized in the inner plexiform layer of the retina, is assessed in four normal individuals. ...

Subjects were asked to match the speeds of two moving random-dot patterns seen through circular apertures. The speed of one pattern that moved horizontally toward the right of a computer screen changed continuously. The speed of this pattern represented the target. It was to be matched with the speed of ...

The upper motion displacement threshold (Dmax) was determined with two-frame motion sequences of random binary luminance patterns, over a range of pattern element sizes and densities. Dmax was little affected by density at small element sizes (less than 5 arcmin), in agreement with previous reports. However, at larger element sizes ...

Development of head neck motion patterns is studied in drinking chickens to examine (1) general motion principles, (2) ontogenetic changes in these patterns, and (3) whether pattern changes are due to scaling effects during growth. Behavioral patterns are analyzed by high speed filming, radiography, and calculation of rotation patterns for ...

The strategy for visual information processing must vary with the specific situation. We assume that in recognition of pre-learnt letter-like patterns under time-pressure conditions, mechanisms of selective attention are involved. We propose that, with simple stimuli, foveation is to the luminance centroids of such patterns, and if normally the latter ...

An infinite number of possible combinations of tidal volume and breathing frequency, as well as pattern of airflow, can achieve the alveolar ventilation required for normal gas exchange. Individuals appear to select one particular pattern. This paper summarises our work relating to differences in the pattern of breathing between individuals ...

Recent work on the retinotectal projection clearly establishes the roles of neuronal activity and position-based cues in the patterning of nerve connections. In some species, the high degree of spatial order has been shown to emerge from a continued process of terminal growth and refinement. The future challenge is now ...

A key question in the area of spatial pattern formation in developmental biology is: how do groups of cells in a homogeneous tissue suddenly differentiate along entirely different developmental paths compared to neighbouring cells? Although experiments are now beginning to provide answers to this question, the mechanisms responsible for the ...

The kinematics of aquatic prey capture were studied in species representing six salamander families (Ambystomatidae, Amphiumidae, Cryptobranchidae, Dicamptodontidae, Proteidae, and Sirenidae) to test the hypothesis that the process of aquatic prey capture is similar in these families. Seven variables were digitized from high-speed video records of prey capture, and a ...

The superior hemifields of five normal left eyes were stimulated by novel equal and opposite contrast pattern onset stimuli which were generated on a cathode ray tube. Patterns consisted of 144 discs, each subtending 60 min arc at the viewing distance of 40 cm and were separated by a distance ...

Penrose hypothesized that fingerprint patterns such as loops, whorls, etc. are formed by ridges corresponding to the lines of curvature of the skin of the embryo at the time when the ridges were being formed. Under this hypothesis, Smith (1979) has shown analytically how some patterns emerge. In this paper ...

The past few years have seen the isolation and characterization of some of the genes involved in the control of limb pattern formation. Their possible role in this fundamental process is discussed in the light of recent data, and an attempt is made to superimpose this molecular approach to patterning ...