Search results for "Percept"

Rollvection versus linearvection: Comparison of brain activations in PET

2004

We conducted a PET study to directly compare the differential effects of visual motion stimulation that induced either rollvection about the line of sight or forward linearvection along this axis in the same subjects. The main question was, whether the areas that respond to vection are identical or separate and distinct for rollvection and linearvection. Eleven healthy volunteers were exposed to large-field (100 degrees x 60 degrees ) visual motion stimulation consisting of (1) dots accelerating from a focus of expansion to the edge of the screen (forward linearvection) and (2) dots rotating counterclockwise in the frontal plane (clockwise rollvection). These two stimuli, which induced appa…

Immediate Effects of Vibration Transmitted to the Hand

1981

Summary Three different research projects have been accomplished on the problems: biomechanical behaviour of the hand-arm-system; subjective sensation; physiological changes. Some of the main results were:—the wrist and—with smaller amplifications—the elbow show resonances at low vibration frequencies (10–20 Hz);—with constant acceleration subjective perception decreases with increasing frequency;—application of static grip force—without vibration—causes significant reduction of the skin temperature, which under vibration stress remains at the same lowered level.

General principles in motion vision: Color blindness of object motion depends on pattern velocity in honeybee and goldfish

2011

AbstractVisual systems can undergo striking adaptations to specific visual environments during evolution, but they can also be very “conservative.” This seems to be the case in motion vision, which is surprisingly similar in species as distant as honeybee and goldfish. In both visual systems, motion vision measured with the optomotor response is color blind and mediated by one photoreceptor type only. Here, we ask whether this is also the case if the moving stimulus is restricted to a small part of the visual field, and test what influence velocity may have on chromatic motion perception. Honeybees were trained to discriminate between clockwise- and counterclockwise-rotating sector disks. S…

Collision with and avoidance of obstacles by blind cave fish Anoptichthys jordani (Characidae).

1985

Blind Mexican cave fish (Anoptichthys jordani) were released into unknown surroundings and their swimming tracks were recorded. During the first 24 h in a new tank, i.e., in unfamiliar environments, the average swimming velocity of the fish was higher than during the remaining time in the tank. Collision with obstacles was recorded by an electrical contact detection method. Single frame analysis of video-recordings revealed that collision can be correlated with tail movements when the fish is close to an obstacle, whereas avoidance correlates with gliding during approach to an obstacle. These behavior patterns are discussed in the context of the flow field hypothesis and inhibition of the l…

There is no clam with coats in the calm coast: delimiting the transposed-letter priming effect.

2009

In this article, we explore the transposed-letter priming effect (e.g., jugde–JUDGE vs. jupte–JUDGE), a phenomenon that taps into some key issues on how the brain encodes letter positions and has favoured the creation of new input coding schemes. However, almost all the empirical evidence from transposed-letter priming experiments comes from nonword primes (e.g., jugde–JUDGE). Indeed, previous evidence when using word–word pairs (e.g., causal–CASUAL) is not conclusive. Here, we conducted five masked priming lexical decision experiments that examined the relationship between pairs of real words that differed only in the transposition of two of their letters (e.g., CASUAL vs. CAUSAL). Result…

Do transposed-letter similarity effects occur at a prelexical phonological level?

2006

Nonwords created by transposing two letters (e.g., RELOVUTION) are very effective at activating the lexical representation of their base words (Perea & Lupker, 2004). In the present study, we examined whether the nature of transposed-letter (TL) similarity effects was purely orthographic or whether it could also have a phonological component. Specifically, we examined transposed-letter similarity effects for nonwords created by transposing two nonadjacent letters (e.g., relovución– REVOLUCIÓN) in a masked form priming experiment using the lexical decision task (Experiment 1). The controls were (a) a pseudohomophone of the transposed-letter prime ( relobución– REVOLUCIÓN; note that B an…

Decomposing encoding and decisional components in visual-word recognition: a diffusion model analysis.

2014

In a diffusion model, performance as measured by latency and accuracy in two-choice tasks is decomposed into different parameters that can be linked to underlying cognitive processes. Although the diffusion model has been utilized to account for lexical decision data, the effects of stimulus manipulations in previous experiments originated from just one parameter: the quality of the evidence. Here we examined whether the diffusion model can be used to effectively decompose the underlying processes during visual-word recognition. We explore this issue in an experiment that features a lexical manipulation (word frequency) that we expected to affect mostly the quality of the evidence (the dri…

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 …

Effect of Context on the Perception of Pitch Structures

2006

Classification of Plant Ecological Units in Heterogeneous Semi-Steppe Rangelands: Performance Assessment of Four Classification Algorithms.

2021

Plant Ecological Unit’s (PEUs) are the abstraction of vegetation communities that occur on a site which similarly respond to management actions and natural disturbances. Identification and monitoring of PEUs in a heterogeneous landscape is the most difficult task in medium resolution satellite images datasets. The main objective of this study is to compare pixel-based classification versus object-based classification for accurately classifying PEUs with four selected different algorithms across heterogeneous rangelands in Central Zagros, Iran. We used images of Landsat-8 OLI that were pan-sharpened to 15 m to classify four PEU classes based on a random dataset collected in the field (40%). …