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At least 289 records · Page 16Linked to original sources
PubMed2005

Motion adaptation: net duration matters, not continuousness.

Motion processing is strongly adaptable. Adaptation strength generally increases with motion duration. Little is known, though, about the effect of motion onsets and offsets, which might be relevant if adaptation is not based on motion duration per se, but on the recent cumulated activity of motion-processing mechanisms. Thus, we presented intermittent motion with three different onset rates for adaptation. The duty cycle was kept constant at 33% while the rate of motion onsets was either 1.4, 2.8, or 5.6 per second. Stationary stimuli and continuous motion were used as reference conditions. The amplitude of the N2 component of human motion visual evoked potentials was used to quantify adaptation. All three onset rates induced virtually identical amounts of adaptation (occipitally, P=0.71; occipito-temporally, P=0.27), suggesting that the continuousness of the stimulus does not play an important role in motion adaptation. This was confirmed by measuring the motion aftereffect psychophysically.

Adaptation, Physiological↗
PubMed1986

Temporal aspects of spatial adaptation. A study of the tilt aftereffect.

Growth and decay characteristics of the tilt aftereffect were studied for aftereffects induced by normal or continuous adaptation routines, and for aftereffects induced by successive or spaced adaptation to the same or different orientations on an adapt-partial decay-readapt schedule. In the continuous adaptation condition, growth and decay of the aftereffect were logarithmic functions of time. There was no evidence for saturation after 30 min adaptation. Aftereffect decay following spaced adaptation progresses as by continuous adaptation, but an adapting stimulus introduced during recovery from previous adaptation is more effective on the time scale than when introduced to a fully recovered system, summing approximately linearly with the residual aftereffect and off-setting the recovery process to zero. A second adapting stimulus whose orientation is of opposite sign (ccw vs cw) induces a two-phased decay process consisting of an early cancellation and a later enhancement of the original aftereffect. A two-stage model of adaptation is proposed.

Adaptation, Ocular↗
PubMed1987

Saturation of the tilt aftereffect.

The tilt aftereffect increases as a logarithmic function of adapting time, reaches saturation after approx 1 hr and decays on a symmetric, logarithmic time-course. This is similar to the time-course of contrast threshold elevation, suggesting that threshold and suprathreshold aftereffects are based on similar type of adaptation processes.

Adaptation, Ocular↗
PubMed1982

Interaction between perceived and imagined rotation.

In Experiment 1, subjects performed a mental-rotation task in which they were timed as they decided whether rotated letters were normal or backwards. Between presentations of the letters, they watched a rotating textured disk that induced an aftereffect of rotary movement on the letters. The function relating reaction times to orientation was influenced asymmetrically by the aftereffect, suggesting that perceived movement interacts with imagined movement. Experiment 2 showed that the aftereffect produced a negligible influence on perceived orientation, suggesting that the influence of the aftereffect on mental rotation was not caused by changes in the perceived orientations of the letters. Detailed analysis of the mental-rotation functions suggested that the aftereffect may sometimes have induced subjects to rotate letters through the larger rather than the smaller angle back to the upright where the aftereffect was in the appropriate direction.

Adolescent↗
PubMed1998

A note on state individual differences in accuracy of response imagery: aftereffects and reminiscence.

In two sessions, separated by 7 days, subjects imagined themselves performing a tracking task under a massed practice schedule. After conditions of interpolated rest and no-rest, which were counterbalanced across sessions, subjects actually performed the tracking task. During imagery practice, subjects verbally reported the temporal component of the task. The temporal accuracy of verbal reports varied widely across subjects, but not within subjects. Furthermore, a performance gain was demonstrated as a function of interpolated rest versus no-rest (reminiscence effect). Finally, the accuracy of verbal reports predicted imagery aftereffects, but not reminiscence effects.

Figural Aftereffect↗
PubMed2004

Visual aftereffects: cortical neurons change their tune.

Recent studies of areas V1 and MT in the visual cortex show that exposure to a stimulus can change the contrast sensitivity of cells and shift their peak sensitivity to a new orientation or movement direction. In MT, these shifts can correctly predict illusory changes - visual aftereffects - in movement direction, but in V1, they are more difficult to interpret.

Contrast Sensitivity↗
PubMed2000

Tilt aftereffects in a self-organizing model of the primary visual cortex.

RF-LISSOM, a self-organizing model of laterally connected orientation maps in the primary visual cortex, was used to study the psychological phenomenon known as the tilt aftereffect. The same self-organizing processes that are responsible for the long-term development of the map are shown to result in tilt aftereffects over short timescales in the adult. The model permits simultaneous observation of large numbers of neurons and connections, making it possible to relate high-level phenomena to low-level events, which is difficult to do experimentally. The results give detailed computational support for the long-standing conjecture that the direct tilt aftereffect arises from adaptive lateral interactions between feature detectors. They also make a new prediction that the indirect effect results from the normalization of synaptic efficacies during this process. The model thus provides a unified computational explanation of self-organization and both the direct and indirect tilt aftereffect in the primary visual cortex.

Adaptation, Ocular↗