Change blindness is the striking failure to see large changes that normally would be noticed easily. In contrast, change detection is the successful awareness of the change. The term of change detection pertains primarily to the visual processes involved in ?rst noticing a change. It denotes not only detection proper(i.e., the observer reporting on the existence of the change), but also identi?cation (reporting what the change is) and localization (reporting where it is). Recent studies have shown that while change blindness occurs, observers cannot consciously report changes, but they can unconsciously process and respond to changing stimulus. This phenomenon is called implicit detection. When an implicit detection occurs, the observer's response time, eye movement pattern, event-related potentials and activation brain area are significantly different from those the scene haven’t changes. Implicit detection affects the speed of response, which is typically manifested in Simon effect and Sperling-type tasks. Some experimental evidence from gaze-tracking and forced-choice tasks has pointed towards the possibility that some implicit bottom-up processes may guide visual perception even during change blindness. Participants could correctly guess the change location above chance level even though they claimed that could not notice the change. Comparing eye metrics of detection, non-detection and possible implicit detection, results indicated that eye metrics of fixation count, fixation duration, mean saccade length, and backtrack rate can predict detections and non-detections. Additionally, gaze plots of possible implicit detections revealed signature distinguish eye movement search patterns. Differential brain activity for changes during change blindness compared to no change condition can be observing. Brain registers visual changes very rapidly, less than 100ms after the change onset, even when the subjects are not aware of these changes. Comparing the ERPs which participants were subjectively unaware of the change and localized it correctly versus incorrectly. At the early latencies of 30-80 after change onset can observe different responses, the P3 component was strictly to the parietal electrodes for implicit detection. Change blindness does not preclude the encoding of the prechange and postchange objects’ identities and the comparison of their semantic content. There is a semantic mismatch ERP effect, that is, a more negative-going ERP resembling the N400 effect, albeit at longer latencies. Theta activity in the right superior temporal gyrus(rSTG) was noted in undetected visual change responses relative to the absence of change. Transcranial magnetic stimulation(TMS) induced disruption over this area has been shown to directly increase change blindness rates. Some research show anterior prefrontal involvement in implicit detection processes. Neuroimaging and neurostimulation evidence that the dorsolateral and anterior prefrontal cortex can operate on non-conscious information in a manner that goes beyond automatic forms of sensorimotor priming and which may support implicit detection. A short-latency tecto-thalamic pathway that projects directly to the amygdala and bypasses the visual cortex has been implicated in the implicit processing of fearful faces and aversively conditioned visual stimuli.