Biomedical subjects

Jochen Laubrock

Publications and source records attributed to Jochen Laubrock.

3 recordsLinked to original sources

PubMed2006

SWIFT explorations of age differences in eye movements during reading.

Research on eye movements in reading has made significant advances during the past few years, due to both experimental and computational research. Age effects have not been extensively studied, but the overall pattern suggests more quantitative than qualitative differences in fixation durations and fixation probabilities. Here we focus on age-differential effects of word frequency on reading time and on probabilities of skipping a word or regressing to previous ones. We present an overview of SWIFT [Engbert, R., Nuthmann, A., Richter, E.M., Kliegl, R., 2005. SWIFT: a dynamical model of saccade generation during reading. Psychological Review 112, 777-813], a fully implemented computational model of saccade generation and lexical processing during reading, based on spatially distributed processing over several words. Preliminary simulations of age differences recovered most, but not all experimental effects. Age differences in parameter estimates point towards an important role of visual acuity for oculomotor as well as lexical processing.

Aging↗

PubMed2005

Shortening and prolongation of saccade latencies following microsaccades.

When the eyes fixate at a point in a visual scene, small saccades rapidly shift the image on the retina. The effect of these microsaccades on the latency of subsequent large-scale saccades may be twofold. First, microsaccades are associated with an enhancement of visual perception. Their occurrence during saccade target perception could, thus, decrease saccade latencies. Second, microsaccades are likely to indicate activity in fixation-related oculomotor neurons. These represent competitors to saccade-related cells in the interplay of gaze holding and shifting. Consequently, an increase in saccade latencies would be expected after microsaccades. Here, we present evidence for both aspects of microsaccadic impact on saccade latency. In a delayed response task, participants made saccades to visible or memorized targets. First, microsaccade occurrence up to 50 ms before target disappearance correlated with 18 ms (or 8%) faster saccades to memorized targets. Second, if microsaccades occurred shortly (i.e., <150 ms) before a saccade was required, mean saccadic reaction time in visual and memory trials was increased by about 40 ms (or 16%). Hence, microsaccades can have opposite consequences for saccade latencies, pointing at a differential role of these fixational eye movements in the preparation of saccade motor programs.

Adult↗

PubMed2005

Microsaccade dynamics during covert attention.

We compared effects of covert spatial-attention shifts induced with exogenous or endogenous cues on microsaccade rate and direction. Separate and dissociated effects were obtained in rate and direction measures. Display changes caused microsaccade rate inhibition, followed by sustained rate enhancement. Effects on microsaccade direction were differentially tied to cue class (exogenous vs. endogenous) and type (neutral vs. directional). For endogenous cues, direction effects were weak and occurred late. Exogenous cues caused a fast direction bias towards the cue (i.e., early automatic triggering of saccade programs), followed by a shift in the opposite direction (i.e, controlled inhibition of cue-directed saccades, leading to a 'leakage' of microsaccades in the opposite direction).

Attention↗