Temporal dynamics of attentional selection of space, features and featureconjunctions in human vision
Final Report Abstract
We investigated human visual attention when selection of relevant stimuli is concurrently based on multiple properties such as spafial location, color, orientation or direction of motion. Previous research investigating concurrent selection of spatial locations and features has led to seemingly contradicting findings: one line of research has consistently found a global effect, i.e. attended features are preferentially processed across the visual field. However, another line of research has found evidence for hierarchic selection, according to which attended features are only preferentially processed at attended locations. To resolve this controversy, we conducted multiple experiments in which we recorded steady-state visual evoked potentials (SSVEPs) elicited by concurrently presented flickering stimuli in order to track the allocation of attention in such multi-stimulus displays. These experiments revealed that attended features are enhanced globally in early visual areas even when this explicitly conflicts with the task at hand. This global effect seems to be of equal magnitude across the visual field and also spreads across object boundaries. Furthermore, concurrent attentional selection of two non-spatial features (i.e. feature-conjunctions) is accomplished by parallel and independent selection of the single features, indicating that feature-selection is not only global across space, but also across other non-spatial feature-dimensions. These findings provide compelling evidence that features are selected globally. We were however able to clearly delineate the conditions under which hierarchical rather than global selection of features can be observed by tracking the time-course of enhancement of attended features at attended and unattended locations, thereby attaining the main goal of the present project. Additionally, we investigated the combined effect of bottom-up contrast biases and feature attention on stimulus processing in visual cortex and employed the SSVEP-technique to quantify attentional allocation in dynamic visual scenes when participants track multiple moving objects. In summary, we studied how multiple attentional mechanisms, such as selection of locations, features and objects and competitive stimulus interactions work together to prioritize processing of relevant information and thereby allow for coherent behavior. Our results resolved a central contradiction arising from previously separate theoretical frameworks of attentional selection of features and locations. The theoretical findings and technical refinements of the SSVEP-technique resulting from the present project portend many future applications leading to an enhanced understanding of human performance in complex dynamic visual scenes.
Publications
- (2011). Tracking the allocation of attention in visual scenes with steady-state evoked potentials. In Posner Ml (Ed), Cognitive Neuroscience of Attention, Second Edition. New York: Guilford, pp 197-216
Andersen SK, Müller MM, Hillyard SA
- (2012). Attention facilitates objects and features in parallel in early visual areas. Poster presented at Psychologie & Gehirn 2012 in Jena
Andersen SK, Hillyard SA
- (2012). Bottom-up biases in feature-selective attention. Journal of Neuroscience, 32(47), 16953-16958
Andersen SK, Müller MM, Martinovic J
- (2013). Measuring target detection performance in paradigms with high event rates. Clinical Neurophysiology. 124(5), 928-940
Bendixen A, Andersen SK
(See online at https://doi.org/10.1016/j.clinph.2012.11.012) - (2013). Sustained multifocal attentional enhancement of stimulus processing in early visual areas predicts tracking performance. Journal of Neuroscience. 33(12), 5346-5351
Störmer VS, Winther GN, Li S-C, Andersen SK
(See online at https://doi.org/10.1523/JNEUROSCI.4015-12.2013)
