Biomedical subjects

R H Van der Lubbe

Publications and source records attributed to R H Van der Lubbe.

3 recordsLinked to original sources

PubMed2001

Focused attention reduces the effect of lateral interference in multi-element arrays.

Lateral interference of nearby irrelevant flankers may be reduced when attention is already focused at a relevant position. This hypothesis was tested in three experiments with multi-element arrays consisting of one target and several neutral flankers with reaction time (RT) and proportion of errors (PE) as dependent variables. The arrays were preceded by peripheral cues that varied in size to induce different levels of focused attention. In a first experiment, the eccentricity effect was shown to be affected by attention, but no support was found for a reduction of lateral interference in the case of focused attention. However, these results may be due to an attentional bias for central elements. Two additional experiments were performed in which target-flanker distance was manipulated. RTs and PEs showed that the effect of target-flanker distance was smaller when the precise target position was indicated by a peripheral precue. Thus, focused attention seems to reduce the effect of lateral interference. These results can be explained most easily by a model in which attention already affects early perceptual processing.

Adult↗

PubMed2000

Location selection in the visual domain.

According to A.H.C. Van der Heijden (1992), attentional selection of visual stimuli can be considered as location selection. Depending on the type of task, location selection can be considered to be automatic (e.g., in case of abrupt onsets), directly controlled (e.g., in case of symbolic precues), or indirectly controlled (e.g., in case of visual search). In tasks with symbolic precues a contralateral enhancement of the P1 event-related potential (ERP) component has been found, whereas in visual search tasks a contralateral enhancement of the N2 component has been found. We hypothesized that both lateralized effects reflect the influence of location selection, which differs only in its moment of activation. Linear arrays (a target among five distractors, presented at two eccentricities) requiring left or right responses, were preceded by cues indicating either the precise target location or the side of the target, or by bilateral cues that indicated all array positions. Array-evoked ERPs, corrected for cue-evoked and interactive effects, showed not only lateralized but also target location-specific effects for both components, which supports the view that, depending on the type of task, either the P1 or the N2 component reflect the influence of location selection.

Adult↗

PubMed1999

The influence of peripheral precues on the tendency to react towards a lateral relevant stimulus with multiple-item arrays.

Responses are faster when the side of the stimulus and response correspond than when they do not correspond. This has been ascribed to the influence of a spatial code on response selection. Regarding the origin of this code, three hypotheses were proposed that all assume that spatial codes decay as a function of time: the attention shift hypothesis, the static reference hypothesis, and the dynamic reference hypothesis. Arrays (a target among five distractors) requiring left or right responses, were preceded by peripheral cues indicating either the target position, the side of the target, or all array positions. Reaction times (RT), proportions correct, the response-locked lateralized readiness potential (LRP), and RT distributions were examined. A correspondence effect was present on RTs when all positions or the relevant side were cued, independently of response speed. No correspondence effect was found when the cue indicated the target position. The LRP results indicate that the correspondence effect is at least partially due to an effect at the level of motor preparation. The results favor the attention shift hypothesis which assumes that spatial codes are generated whenever there is a shift of attention.

Adult↗