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Biomedical subjects

M Vitkovitch

Publications and source records attributed to M Vitkovitch.

4 recordsLinked to original sources

Inhibitory effects during object name retrieval: the effect of interval between prime and target on picture naming responses.

Three picture naming experiments are reported which examine the relationship between the apparent inhibition of a response on one trial, and naming latency on the subsequent trial. The design of each experiment involves the presentation of prime and target pairs, either presented in succession (Lag 1 condition), or separated by two intervening unrelated trials (Lag 3 condition). A control condition is also included. In Experiment 1, a speeded picture naming task is used, and naming errors are analysed. Target pictures are misnamed at above chance rates with the name of the semantically related prime picture in the Lag 3 condition. In contrast, these prime-related errors do not occur in the Lag 1 condition, suggesting a brief inhibitory effect. If primes are briefly inhibited, then target naming latencies immediately following a related prime should be quicker than target latencies in the Lag 3 condition. Experiment 2 confirms this pattern of results, using exactly the same stimuli and design, but standard naming instructions. Experiment 3 examines whether the inferred inhibition is the result of a self-inhibitory mechanism, using a repetition priming paradigm. If Lag 1 prime representations are self-inhibited, then facilitatory effects from prime/target repetition should be stronger in the Lag 3 condition, than in the Lag 1 condition. The data from Expt 3 were not consistent with this prediction. Taken together, the results of the three experiments suggest that a brief inhibitory effect occurs after retrieval of an object name, and that the inhibition may be accomplished by mechanisms other than self-inhibition.

Adolescent↗

Effect of video frame rate on subjects' ability to shadow one of two competing verbal passages.

In a study addressing future use of video-telephone systems, the ability of 52 young adults with normal hearing to shadow verbal passages was assessed when they could both hear and observe the speaker. This performance was compared to performance in an audio-alone condition. The passages were presented against an irrelevant background message. Effects of varying the video frame rate (i.e., the rate at which frames were sampled) were examined, using rates of 8.3, 12.5, 16.7, and 25 Hz. The presence of the visual image of the relevant speaker always improved performance when compared with a baseline audio-alone condition. The motion of the speaker's face may generally support the focusing of attention on the target message. However, effects of video frame rate were also apparent, suggesting that specific visual cues became available as the temporal resolution improved. When frame rates of 8.3 Hz and the maximum available rate of 25 Hz were compared, shadowing performance was significantly better across the subject group at the higher frame rate. The comparison of frame rates of 12.5 and 25 Hz did not show reliably improved performance across the whole subject group at 25 Hz, although a small number of subjects seemed to benefit. This suggests there may be some differences in the visual cues used by subjects and consequent differences in the way individuals perform under different frame rates. Performance at 16.7 and 25 Hz did not differ, and this is consistent with previous research that tested people with hearing loss.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

Visual field differences in an object decision task.

Two experiments are reported which investigate hemispheric processing in an object decision task. Experiment 1 used 40 pictures of objects, and 40 pictures of nonobjects, and subjects decided manually whether each lateralized stimulus represented an object. Results indicated an interaction between visual field and response (yes versus no). There was a right visual field advantage for positive responses, but no difference between visual field for negative responses. Positive responses were faster than negative responses, and this effect was more marked for right visual field presentations. These results were replicated in a second experiment. The results are interpreted as reflecting a left hemisphere superiority at accessing stored structural descriptions of known objects. The possibility that left and right hemispheres use different methods of carrying out the task is also discussed.

Adult↗

Hemispheric differences in the processing of pictures of typical and atypical semantic category members.

In the following experiment, pictures of typical and atypical category members were categorised by subjects after presentation to either the left or right visual field. Three different categories were investigated. The results in part replicate a previous study by Zaidel (1987), who found an interaction between visual field and typicality. She suggested this result might reflect different conceptual organisations for each hemisphere. However, in the present study, the Visual Field x Typicality interaction was not evident in the two other categories investigated, and it is argued that any conclusion regarding conceptual organisation may be premature. Further work is needed to address the issue.

Adult↗