Hand Position And Hand Posture Biases Visual Processing Toward Flankers

A number of recent studies have demonstrated that objects near the hands is processed differently,and often preferentially,compared with areas distant from the hands.This phenomenon is called nearby-hand effects.However,it is not known whether the near-hand bias is automatic,or because of a strategic prioritization of search at near-hand space.Moreover,hand posture and the actions these postures afford may also influence changes in visual processing near the hands,it is still unclear.In the current studies,I used the flanker task paradigm that did not require visual search for the target.A total of 97 college students were randomly selected as subjects.Through three experiments,I examined the influence of hand positions,hand posture,and alternative tool compared with the hand that affect performance of flanker task,and discussed possible causes and mechanisms for this effect.Experiment 1 aimed to investigate whether hand's proximity of the critical distractor can affect the participants' flanker task performance,using 2(hand position: close to the critical distractor,far from the critical distractor)× 2(trial type: congruency distractor,incongruency distractor)within-subject experiment.Experiment 2,based on experiment 1,uses a 2(gestures: fingers close together near the critical distractor,finger point the critical distractor)×2(trial type: congruency distractor,incongruency distractor)within-subject experiment,to explore whether hand posture and the actions these postures afford can influence the nearby-hand effects or not.Experiment 3 is a comparative study with an alternative tool,using 2(critical distractor indication: hand indication,tool indication)× 2(trial type: congruency distractor,incongruency distractor)within-subject experiment.The experiment discusses whether a familiar tool's proximity in flanker task has a similar substitution effect with hand's proximity,and further investigates the reasons for the visual processing change in the near hand position.Conclusions:(1)Hand position near the critical distractor can enhance the flanker effect.This result supports the automatic attention allocation assumption of the near hand position.(2)The indication of the critical distractor by the hand can significantly slow down the participants' reactions in the flanker task.This result shows that the change on visual processing of the near hand position not only depends on the position of the hand and visual information,but also on the hand posture,and the potential actions and function represented by this gesture.The findings of the current study are consistent with the theory that precision gestures bias processing toward contributions from the parvocellular pathway.(3)No enhancement of the flanker effect was observed with the tool indicating the critical distractor compared to the finger indication.This result suggests that the effect of tool's proximity on visual processing may be more of a strategy than the automatic allocation of attention,compare to the nearby-hand effect.