Pay Attention To The Mechanism Of Action In Sensorimotor Processing In Different States Of Consciousness

Sensorimotor system,an adaptive system facilitating efficient interaction with environmental stimuli,can transform the sensory information of a stimulus into motor information rapidly and elicit motor activation.However,our visual scene is not stable,so it is possible that the currently motor activation is unable to complete the expected task.In this case,we must inhibit this motor activation immediately.This activation-follow-by-inhibition mechanism is the guarantee of sensorimotor processing.The negative compatibility effect(NCE),as first reported by Eimer and Schlaghecken(1998),refers to the counterintuitive phenomenon in which the response performance is lower to the stimulus that has been briefly appeared before.It is generally acknowledged that the NCE is a subliminal effect and induced,at least partially,by the activation-follow-by-inhibition mechanism.Due to the influence of the view that unconscious processing independent of attention,little research examined the modulation of attention on the activation-follow-by-inhibition mechanism.The notion that the NCE is purely subliminal was challenged by Jaskowski et al.(2007),as they reported NCE in a supraliminal condition.Although some recent studies imply that attention might modulate the activation-follow-by-inhibition processing,the question how attention affects the sensorimotor processing in the absence and presence of consciousness is still unknown.Attention can be divided into two dimensions,spatial attention(the process of searching information in an expected spatial range)and temporal attention(the process of searching information in an expected time range).Previous studies have demonstrated that the neuronal mechanisms under spatial attention and temporal attention are independent,at least partially independent.So it is possible that the modulations of spatial and temporal attention on a cognitive processing are different,and they may interact with each other.Accordingly,this study examined how spatial attention and temporal attention modulate the activation-follow-by-inhibition processing.This study developed six experiments attaching to three series of research to investigate the impact of spatial and temporal attention and their interactions on the activation-follow-by-inhibition processing in the absence and presence of consciousness.In this way,the effect mechanism of attention on sensorimotor processing in different conscious levels can be revealed.The results will contribute to the understanding of the mechanisms underlying the NCE and will clarify the intricate relationship between consciousness and unconsciousness to some extent.The first research used event related potentials(ERPs)to investigate whether spatial attention modulates the NCE under different conscious levels employing a mixed paradigm involving the NCE task and a cueing paradigm,in which temporal attention deployed to primes is always constant.Experiment 1 controlled the subliminal prime(the mask was presented in the same position of the prime).The behavioral results showed that the NCE was significantly larger in the valid-cue condition than in the invalid-cue condition.The lateralized readiness potentials(LRP)results showed that the amplitudes of activation components were larger in the valid-cue condition than in the invalid-cue condition,moreover,the inhibitory components in the compatible trials were significantly negative under the valid-cue condition than under the invalid-cue condition.These findings demonstrated that the subliminal activation-follow-by-inhibition processing can be modulated by spatial attention.Experiment 2 manipulated spatial attention for the supraliminal prime(the mask,or rather the distractor,was presented in different positions of the prime).The results showed that the NCE was decreased and even reversed with the increasing spatial attention,which indicating that the supraliminal activation-follow-by-inhibition processing can be modulated by spatial attention.The second research examined whether temporal attention modulates the NCE by manipulating a temporal window of attention in the masked prime paradigm,in which spatial attention deployed to primes is always constant.Experiment 3 controlled the subliminal prime(presented for 17 ms)and found that the NCE was significantly larger when the prime obtains more temporal attention.This result indicated that the subliminal activation-follow-by-inhibition processing can be modulated by temporal attention.Variable prime durations were added to gradually make the prime supraliminal in Experiment 4.The result showed that the NCE was significant when the prime obtains temporal attention,but there is no significant compatibility effect when the prime cannot obtain temporal attention.These findings indicated that temporal attention plays a necessary role in triggering supraliminal activation-follow-by-inhibition processing.The third research aimed to verify the influencing mechanism of the combined spatial and temporal attention on subliminal and supraliminal activation-follow-by-inhibition processing by manipulating the spatial cueing and temporal window simultaneously.Experiments 5 and 6 manipulated the temporal window of attention on the basis of Experiments 1 and 2,respectively.The results showed that significant NCE can be triggered only if the primes obtain spatial and temporal attention simultaneously,it cannot be elicited if lacking of spatial or temporal attention or both of them.These intriguing findings indicated the synergistic effect of combined spatial and temporal attention on activation-follow-by-inhibition processing.According to the results of the three research,we make conclusions as follows:1.Attention can modulate sensorimotor processes regardless of the threshold of consciousness.This study demonstrates a coherent account of the NCE based on inhibitory mechanism of attentional modulation;we term this the attentional modulation account.This account assumes that inhibition leads to the NCE and that inhibitory processes depend on spatiotemporal attentional resources the prime obtained.Regarding the mechanism by which attention modulates inhibitory processing,we speculate that attention strengthens the motor activation and strong activations can be actively inhibited.2.Spatial and temporal attention affects synergistically on sensorimotor process,but not simply overlapping with each other.3.Attentional selection is not only exclusive to the domain of high-level top-down control,but also occurs in unconscious low-level bottom-up automatic processes.This finding challenges the classic cognitive theories and provides the experimental evidence for "attention without consciousness" and also indicates that attention is not sufficient for consciousness.