Recent advances in perception and action

Different effects of spatial separation in action and perception

Spatial distance of response keys has been shown to have an effect on nonspatial tasks in that performance improved if the spatial distance increased. Comparably, spatial distance of stimulus features has been shown to have a performance-improving effect in a (partly) spatial task. Here, we combined these two findings in the same task to test for the commonality of the effect of stimulus distance and the effect of response distance. Thus, we varied spatial distance in exactly the same fashion either between stimuli or between responses in a standard Eriksen flanker task. The results show that spatial distance only affected the processing of stimulus features, while it had no effect on the processing of response features. Regarding the idea of common coding of action and perception (Prinz, 1990), stimulus and response processing should be influenced by spatial distance in the same way so that our data might suggest a boundary for the idea of common coding.

Merkmalsintegration und Abruf als wichtige Prozesse der Handlungssteuerung – eine Paradigmen-übergreifende Perspektive

Zusammenfassung. Die Kognitionspsychologische Grundlagenforschung zur Handlungskontrolle hat inzwischen eine große Zahl sehr spezifischer Aspekte von Handlungen in diversen Experimentalparadigmen isoliert und beleuchtet, sodass der gegenwärtige Forschungsstand durch eine kaum übersehbare Flut unverbundener Phänomene und paradigmen-spezifischer Modellvorstellungen gekennzeichnet ist. In dem hier vorgeschlagenen Rahmenmodell ( Binding and Retrieval in Action Control, BRAC) werden die für Handlungen wichtigsten Prozesse paradigmen-übergreifend beschrieben, systematisch eingeordnet und in ein Rahmenmodell transferiert, bei dem Merkmalsintegration und Merkmalsabruf als wichtige Mechanismen der Handlungssteuerung dienen. Wir zeigen exemplarisch auf, wie das Rahmenmodell etablierte, aber bislang unabhängig voneinander untersuchte Phänomene der Handlungs-Forschung mithilfe derselben Mechanismen erklärt. Dieses Modell birgt neben seiner Ordnungs- und Integrationsfunktion die Möglichkeit, Phänomen auch aus anderen Forschungskontexten in der Sprache des Modells zu reformulieren. Das Modell soll Wissen aus der Kognitionsforschung bzw. Allgemeinen Psychologie innovativ kondensieren und anderen Disziplinen zur Verfügung stellen.

Shared sensory estimates for human motion perception and pursuit eye movements

Are sensory estimates formed centrally in the brain and then shared between perceptual and motor pathways or is centrally represented sensory activity decoded independently to drive awareness and action? Questions about the brain's information flow pose a challenge because systems-level estimates of environmental signals are only accessible indirectly as behavior. Assessing whether sensory estimates are shared between perceptual and motor circuits requires comparing perceptual reports with motor behavior arising from the same sensory activity. Extrastriate visual cortex both mediates the perception of visual motion and provides the visual inputs for behaviors such as smooth pursuit eye movements. Pursuit has been a valuable testing ground for theories of sensory information processing because the neural circuits and physiological response properties of motion-responsive cortical areas are well studied, sensory estimates of visual motion signals are formed quickly, and the initiation of pursuit is closely coupled to sensory estimates of target motion. Here, we analyzed variability in visually driven smooth pursuit and perceptual reports of target direction and speed in human subjects while we manipulated the signal-to-noise level of motion estimates. Comparable levels of variability throughout viewing time and across conditions provide evidence for shared noise sources in the perception and action pathways arising from a common sensory estimate. We found that conditions that create poor, low-gain pursuit create a discrepancy between the precision of perception and that of pursuit. Differences in pursuit gain arising from differences in optic flow strength in the stimulus reconcile much of the controversy on this topic.

Methods to explore the influence of top-down visual processes on motor behavior

Kinesthetic awareness is important to successfully navigate the environment. When we interact with our daily surroundings, some aspects of movement are deliberately planned, while others spontaneously occur below conscious awareness. The deliberate component of this dichotomy has been studied extensively in several contexts, while the spontaneous component remains largely under-explored. Moreover, how perceptual processes modulate these movement classes is still unclear. In particular, a currently debated issue is whether the visuomotor system is governed by the spatial percept produced by a visual illusion or whether it is not affected by the illusion and is governed instead by the veridical percept. Bistable percepts such as 3D depth inversion illusions (DIIs) provide an excellent context to study such interactions and balance, particularly when used in combination with reach-to-grasp movements. In this study, a methodology is developed that uses a DII to clarify the role of top-down processes on motor action, particularly exploring how reaches toward a target on a DII are affected in both deliberate and spontaneous movement domains.