Search results for "Visual Perception"
showing 10 items of 387 documents
Profesora Dr.habil.phys. Ivara Lāča biobibliogrāfija
2018
Latvijas Universitātes rektora, habilitētā fizikas doktora, profesora Ivara Lāča biobibliogrāfiskajā rādītājā ietvertie publicēto darbu (1976-2017) bibliogrāfiskie apraksti sagrupēti nodaļās: Profesora Ivara Lāča monogrāfijas. Profesora Ivara Lāča publikācijas iespieddarbos. Profesora Ivara Lāča elektroniskās publikācijas. Profesora Ivara Lāča rediģētie un recenzētie darbi. Profesora Ivara Lāča vadītās, recenzētās, oponētās disertācijas. Intervijas, sarunas u.c. ar profesoru Ivaru Lāci. Raksti par profesoru Ivaru Lāci.
On the role of the upper part of words in lexical access: evidence with masked priming.
2012
More than 100 years ago, Huey (1908) indicated that the upper part of words was more relevant for perception than the lower part. Here we examined whether mutilated words, in their upper/lower portions (e.g., , , , ), can automatically access their word units in the mental lexicon. To that end, we conducted four masked repetition priming experiments with the lexical decision task. Results showed that mutilated primes produced a sizeable masked repetition priming effect. Furthermore, the magnitude of the masked repetition priming effect was greater when the upper part of the primes was preserved than when the lower portion was preserved –this was the case not only when the mutilated words we…
The effect of neighborhood frequency in reading: Evidence with transposed-letter neighbors
2007
Transposed-letter effects (e.g., jugde activates judge) pose serious models for models of visual-word recognition that use position-specific coding schemes. However, even though the evidence of transposed-letter effects with nonword stimuli is strong, the evidence for word stimuli is scarce and inconclusive. The present experiment examined the effect of neighborhood frequency during normal silent reading using transposed-letter neighbors (e.g., silver, sliver). Two sets of low-frequency words were created (equated in the number of substitution neighbors, word frequency, and number of letters), which were embedded in sentences. In one set, the target word had a higher frequency transposed-le…
Automatic brain response to facial emotion as a function of implicitly and explicitly measured extraversion.
2010
Extraversion/introversion is a basic dimension of personality that describes individual differences in social behavior and sensory sensitivity. Previous neuroimaging research exclusively relied on self reports for assessing personality traits. In recent years, implicit measures of personality have been developed that aim at assessing the implicit self-concept of personality and complement self report instruments which are thought to measure aspects of the explicit self-concept of personality. In the present study functional magnetic resonance imaging was used to examine automatic brain reactivity to facial expression as a function of both implicitly and explicitly measured extraversion in 3…
On the interpretation of optical illusions.
1973
If excited by stimuli adjacent in space and time, the optical system frequently perceives illusions in the form of apparent movements. These effects may be attributed to the dynamic properties of the retinal nerve nets. On the basis of a specific psychophysical experiment the mechanism underlying the generation of optical illusions is interpreted by the methods of systems theory and its use in systems analysis is discussed. It is shown that for the perception of apparent movements the transit times of the signals in the dendrites are particularly important.
Honeybee (Apis mellifera) vision can discriminate between and recognise images of human faces.
2005
SUMMARY Recognising individuals using facial cues is an important ability. There is evidence that the mammalian brain may have specialised neural circuitry for face recognition tasks, although some recent work questions these findings. Thus, to understand if recognising human faces does require species-specific neural processing, it is important to know if non-human animals might be able to solve this difficult spatial task. Honeybees (Apis mellifera) were tested to evaluate whether an animal with no evolutionary history for discriminating between humanoid faces may be able to learn this task. Using differential conditioning, individual bees were trained to visit target face stimuli and to …
Subliminal fear priming potentiates negative facial reactions to food pictures in women with anorexia nervosa.
2010
BackgroundTo investigate hedonic reactivity and the influence of unconscious emotional processes on the low sensitivity to positive reinforcement of food in anorexia nervosa (AN).MethodAN and healthy women were exposed to palatable food pictures just after a subliminal exposure to facial expressions (happy, disgust, fear and neutral faces), either while fasting or after a standardized meal (hungerversussatiety). Both implicit [facial electromyographic (EMG) activity from zygomatic and corrugator muscles, skin conductance, heart rate, and videotaped facial behavior] and explicit (self-reported pleasure and desire) measures of affective processes were recorded.ResultsIn contrast to healthy wo…
Grasp-specific motor resonance is influenced by the visibility of the observed actor
2016
AbstractMotor resonance is the modulation of M1 corticospinal excitability induced by observation of others' actions. Recent brain imaging studies have revealed that viewing videos of grasping actions led to a differential activation of the ventral premotor cortex depending on whether the entire person is viewed versus only their disembodied hand. Here we used transcranial magnetic stimulation (TMS) to examine motor evoked potentials (MEPs) in the first dorsal interosseous (FDI) and abductor digiti minimi (ADM) during observation of videos or static images in which a whole person or merely the hand was seen reaching and grasping a peanut (precision grip) or an apple (whole hand grasp). Part…
Seeing with the visual cortex
1984
A short analysis of the input-output organization of the primary visual cortical areas in the cat and monkey is followed by a description of the salient microelectrophysiological properties of retino-geniculo-cortical system neurons. It is concluded that a strict hierarchical model of cortical processing of visual information is no longer tenable.
Network of Concepts and Ideas
2010
We present the results of an experiment designed to investigate the way information is organized and stored in the human brain. In particular, we are using controlled stimuli to reverse engineer the networks of ideas and concepts in order to answer the following questions. (1) Are the networks of ideas and concepts in the human brain invoked by verbal and visual stimuli distinct from each other? The answer appears to be no for the network of ideas and inconclusive for the network of concepts. (2) What is the topology of these networks? Our experimental results show that both are small-world networks, with the network of ideas being random and the network of concepts scale-free.