If the fast circuit bypasses the occipital lobe and other perception-related centers, how does the amygdala categorize and derive meaning from the information coming in from the retina?
6:47 This sounds.. weird. Do you know if this study has been replicated and what were the results? How is it possible for one to process the image unconsciously; not consciously, and show or/and feel fear. Also how can we trust the blindsight people who say don't see but they react to moving stimulus?
There have been replications of this type of unconscious priming, but results aren't clear-cut, and so there's still debate about Zajonc's "affective primacy hypothesis" and how much these types of stimuli might influence behavior. One of the challenges of this type of research is that if the influences are subtle it can be difficult to measure them, and hard to separate a real effect from random noise or variation. This unconscious fear priming is proposed to be slight, so that participants don't necessarily "feel" the fear, which, if they did, would suggest some conscious processing. But as I said, this makes it very difficult to try to assess, usually by seeing if it influences their decision-making in a subsequent task. "Trusting" blindsight reports is also challenging, and one problem is that this condition is rare. Different case studies may be with patients who don't have the same amount or types of damage, which makes it very difficult to generate a precise explanation and the degree of conscious or unconscious visual perception may vary across people. There are several proposed explanations, and it may be the case that multiple explanations could be correct depending on the particular patient's damage and level of vision loss.
So what your saying is that the blind person can process visual stimulation in both fast and slow ways , yet my question is if a non blind person closed his eye , would he rely only on one way wether it’s slow or fast or will he rely in both ? because if I closed my eyes and some one through something in my face I won’t be able to react upon it
A sighted person with closed eyes is blocking all of the pathways and thus wouldn't be able to react. Many types of blindness also affect all pathways and thus leave the person unable to react to visual stimuli. In blindsight, however, only some of the connections are damaged (the ones corresponding to conscious visual perception) and the person still has some functioning connections that relate to unconscious visual processing and therefore the person can show responses to some types of stimuli. Hope that is clearer!
The idea is that these systems are parallel and are both working at the same time and influencing each other. They can appear to be sequential (in the visual flinching example) because the low road is faster (it involves fewer neural connections) but both are still working simultaneously.
A blind person can not see , however , reacts ? Is there some other signal like sound or movement of hand that he can sense the swiftness or something? I don’t get it.
The idea is that the person is consciously blind, but still has some unconscious visual processing. A simplified way to think about it is to imagine two wires coming from the eyes. The first wire sends visual information to the occipital lobe for detailed conscious processing (slow pathway) and the second wire sends visual information to the limbic system for simple unconscious emotional processing (fast pathway). Now imagine that we cut only the first wire. The person would not consciously be able to see (and would report being blind) but they would still have the second wire intact, so they could still have simple emotional responses to visual stimuli even though they can't consciously "see" them (because the information is not being sent to the occipital lobe). Hope this is clearer!
