Wahrnehmungskonflikte: Binokulare Rivalität, Stereopsis, Aufmerksamkeit

In our everyday live we experience many conflict situations. In this work three different types of conflict are presented: Binocular rivalry, Stereopsis and Attention. Binocular rivalry ensues when both eyes are confronted with two sufficient different pictures. This is resolved by a temporal segregation of both pictures in awareness. The pupil reacts to a change in perceived brightness and does so earlier as an actual behavioral report. The pupil is an indicator for upcoming rivalry shifts. Under normal viewing condition the visual system is provided by many different depth cues, as disparity and perspective. A combination of cues, indicting for the same or different spatial orientation, revealed, that cues are used to estimated depth; without regard to a potential antagonism. The visual system is flooded by information. In order to separate relevant and irrelevant data, attention is employed. Neuronal networks are compared between humans and monkeys performing the same task under fMRI

How Much of the “Unconscious” is Just Pre – Threshold?

Visual awareness is a specific form of consciousness. Binocular rivalry, the alternation of visual consciousness resulting when the two eyes view differing stimuli, allows one to experimentally investigate visual awareness. Observers usually indicate the gradual changes of conscious perception in binocular rivalry by a binary measure: pressing a button. However, in our experiments we used gradual measures such as pupil and joystick movements and found reactions to start around 590 ms before observers press a button, apparently accessing even pre-conscious processes. Our gradual measures permit monitoring the somewhat gradual built-up of decision processes. Therefore these decision processes should not be considered as abrupt events. This is best illustrated by the fact that the process to take a decision may start but then stop before an action has been taken – which we will call an abandoned decision process here. Changes in analog measures occurring before button presses by which observers have to communicate that a decision process has taken place do not prove that these decisions are taken by a force other than the observer – hence eliminating “free will” – but just that they are prepared “pre-thresholdly,” before the observer considers the decision as taken

A new species and new records of lithodid crabs (Crustacea: Decapoda: Lithodidae) from the Crozet and Kerguelen Islands area (Subantarctica).

5 páginas, 2 figuras, 1 tabla.Four species of lithodid crabs from waters (240– 2,005 m) in the Crozet and Kerguelen Islands area were studied. One new species, Neolithodes duhameli, is described. Three other species, N. capensis Stebbing, Paralomis anamerae Macpherson and P. birsteini Macpherson are reported for the first time from these localities. The new species, N. duhameli (620–1,500 m), is the fourth representative of the genus in Subantarctic waters and belongs to the group of species possessing a carapace, chelipeds and walking legs covered with numerous spinules or spiniform granules in addition to spines. However, the new species is distinguishable from others in the genus by the long, strong spines on the carapace and pereiopods. The finding of two species of Paralomis clearly extends their geographic ranges in the Southern Ocean: P. anamerae was previously known only in waters of the Falkland Islands and the circumpolar distribution of P. birsteini is supported. The observation of N. capensis also extends its previously described range from South Africa, in the Cape region, to Subantarctic waters. As a result of this study, 14 species of the family Lithodidae are now known from Antarctic and Subantarctic waters; and most can be considered endemic to these waters.Peer reviewe

Perceptual Conflict: Binocular Rivalry, Stereopsis and Attention

In our everyday live we experience many conflict situations. In this work three different types of conflict are presented: Binocular rivalry, Stereopsis and Attention. Binocular rivalry ensues when both eyes are confronted with two sufficient different pictures. This is resolved by a temporal segregation of both pictures in awareness. The pupil reacts to a change in perceived brightness and does so earlier as an actual behavioral report. The pupil is an indicator for upcoming rivalry shifts. Under normal viewing condition the visual system is provided by many different depth cues, as disparity and perspective. A combination of cues, indicting for the same or different spatial orientation, revealed, that cues are used to estimated depth; without regard to a potential antagonism. The visual system is flooded by information. In order to separate relevant and irrelevant data, attention is employed. Neuronal networks are compared between humans and monkeys performing the same task under fMRI

On the Mechanics of Immediate Corrections and Aftereffects in Prism Adaptation

Prisms laterally shifting the perceived visual world cause arm movements to deviate from intended targets. The resulting error—the direct effect—both for pointing and throwing movements, usually corresponds to only around half of the prism’s optical power due to an “immediate correction effect”. We investigated the mechanisms of this immediate correction effect. In three experiments with 73 healthy subjects we find that the immediate correction effect is associated with a head and/or eye rotation. Since these rotations are subconscious they are not taken into account by the participants. These subconscious rotations compensate for a large portion of the prism’s optical effect and change the subjective straight ahead. These movements seem to be induced only in a rich visual environment and hence do not take place in the dark. They correspond to the difference between the direct effect and the optical power of the prisms and seem to cause the immediate correction effect. Hence, eye-hand adaptation only adapts to the prism’s optical power minus unconscious head rotation and hence is much smaller than the optical power of the prisms