Biomedical subjects

Adrian von Mühlenen

Publications and source records attributed to Adrian von Mühlenen.

4 recordsLinked to original sources

PubMed2005

Inhibition of return in patients with obsessive-compulsive disorder.

The present study is aimed at replicating and extending previous results by Nelson et al. [Psychiatry Res. 49 (1993) 183], who found decreased inhibition of return (IOR) in patients with obsessive-compulsive disorder (OCD). Thirty OCD patients, 14 psychiatric, and 14 healthy controls participated in a visual cueing experiment. The task required detection of a target stimulus at one of two possible locations. Prior to the target, an uninformative cue appeared at one of these two locations. The Stimulus Onset Asynchrony (SOA) between the cue and the target was systematically varied. We were especially interested in whether severity of OCD symptoms would be negatively correlated with inhibition for previously occupied locations. In accordance with prior research on healthy participants all groups displayed a comparable response pattern: facilitation at the short SOA condition and increasing IOR for the longer SOA conditions. Medication, comorbid depression, and OCD severity did not consistently moderate these effects.

Adult↗

PubMed2004

Integration of competing saccade programs.

Reflexive responses are often in direct competition with voluntary control. We test two opposing explanations for how this competition is resolved with respect to eye movements. One states that the quickest activation wins. The other states that the strongest activation wins. We show that an eye movement is executed according to the strongest activation, with the competition being staged at a common subcortical site.

Humans↗

PubMed2004

Decoupling stimulus duration from brightness in metacontrast masking: data and models.

A brief target that is visible when displayed alone can be rendered invisible by a trailing stimulus (metacontrast masking). It has been difficult to determine the temporal dynamics of masking to date because increments in stimulus duration have been invariably confounded with apparent brightness (Bloch's law). In the research reported here, stimulus luminance was adjusted to maintain constant brightness across all durations. Increasing target duration yielded classical U-shaped masking functions, whereas increasing mask duration yielded monotonic decreasing functions. These results are compared with predictions from 6 theoretical models, with the lateral inhibition model providing the best overall fit. It is tentatively suggested that different underlying mechanisms may mediate the U-shaped and monotonic functions obtained with increasing durations of target and mask, respectively.

Cerebral Cortex↗

PubMed2003

Sit-and-wait strategies in dynamic visual search.

The role of memory in visual search has lately become a controversial issue. Horowitz and Wolfe (1998) observed that performance in a visual search task was little affected by whether the stimuli were static or randomly relocated every 111 ms. Because a memory-based mechanism, such as inhibition of return, would be of no use in the dynamic condition, Horowitz and Wolfe concluded that memory is likewise not involved in the static condition. However, Horowitz and Wolfe could not effectively rule out the possibility that observers adopted a different strategy in the dynamic condition than in the static condition. That is, in the dynamic condition observers may have attended to a subregion of the display and waited for the target to appear there (sit-and-wait strategy). This hypothesis is supported by experimental data showing that performance in their dynamic condition does not differ from performance in another dynamic condition in which observers are forced to adopt a sit-and-wait strategy by being presented with a limited region of the display only.

Adult↗