The ability to direct the gaze to optimal areas in the environmental context, at the appropriate time, is central to success in all sports. The aim of this study was to changes determine the elements of QE, during the run a reactivity launcher targeting skill, under different environmental demands. That was done to identify perceptual - cognitive effects performance-based infrastructure processes. Thus, 8 Athletes (22-28 Years old) with at least 5 years’ experience in dart throwing, in a counterbalanced manner performed under four target conditions of constraints environmental. Regulatory conditions (stationary/in motion) and inter-trial variability (present/absent) created four target conditions for reaction. During the run a launcher targeting skill and was continuously recorded characteristics related to gaze behavior in each scenario. In each condition, 10 trails 20 seconds conducted. Gaze behavior using an eye-tracking device Dikablis Professional Wireless model recorded and analyzed using DLab software information processing system and variance (ANOVA) with repeated measures. Results showed that there was significant between averages QE in four different environmental contexts (P≤0.001). The fastest QE onset was observed stationary – no inter-trial variability and QE offset and QE period belonged to in motion – no inter-trial variability and in motion– inter-trial variability. In general investigating factors involved in skillful performance in different implementation conditions in response to various constraints can be facilitator and effective in identifying important factors learning motor skills.

Focus of Attention and Quiet Eye (QE) of the affecting variables on aiming task performance in recent decades have always been interesting for psychologist and sport science researchers. The purpose of this study was to investigate the effectiveness of attention instructions on gaze behavior and accuracy of dart throwing of novice in low and high task load. In a semi-experimental design with repeated measurements, participant performed dart throwing under three attentional condition (internal, external and control) in two different task load (low and high). Result showed the external focus in high load task improved accuracy of dart throwing than internal focus; in the event that, for low load task there was no significant difference between the attentional conditions. Also, for QE none of attention, load task and their interaction effects was not significant. Results of research for performance supported the constrained action hypothesis; and in contrast to the conscious processing hypothesis. Also the result of gaze behavior suggests several interesting areas for future research.