Processing ability is a very broad and flexible category according to many researchers. In fact, the quote mentioned above suggests that we often fail to notice things happening right in front of us (unexpected events that are often striking), either because we were completely absorbed in something else or because we had so much to do at the moment. at the same time that we could not pay attention to it. We all haven't at least once seen a friend waving at us while eating in the cafeteria or walking down a crowded street. The first question we need to ask ourselves is: how many things can we attend to at once? The truth is that we failed to perceive this friend because of a phenomenon called “inattentional blindness.” The problem is that the richness of our visual experience leads us to believe that our visual representation will include and preserve the same amount of detail (Levin et al 2000). In this article we will see the different theories of inattentional blindness and the classic theories demonstrating this paradigm. Classic theories demonstrating the inattentional blindness paradigm are (1) perceptual load, (2) inattentional amnesia, and (3) expectancy. (1) ) The effects of perceptual load on the appearance of inattentional blindness have been clearly demonstrated by experiment. In an experiment conducted by Finch and Lavie in 2007, participants were presented with an identical series of crossed central targets with two arms of clearly different colors (blue and green) and slightly different lengths. Participants were divided into two groups, one performing an easy task (low-load condition) and the other a more difficult task (high-load condition). The group doing the easier task only had to make a color distinction between the two...... middle of paper ......We also saw that memory can also play an important role , but this is not yet clearly demonstrated. Additionally, some studies reveal that congruence (vs. incongruence) of the critical stimulus can also play an important role in awareness, a phenomenon called the cocktail effect. Such a phenomenon clearly shows that the relevance of stimuli plays a key role in consciousness and perception. The cocktail effect is the phenomenon of being able to focus one's auditory attention on a particular stimulus while filtering out a series of other stimuli, in the same way that one can concentrate on a single conversation in a noisy room while by being able to hear. if someone shouts their name or other relevant stimuli (dangerous words for example). However, sometimes we fail to perceive something that is happening right in front of us. It's easy to miss something you're not looking for.