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Differences between hand eye coordination and reflexes

  1. Aug 15, 2017 #1
    What are the differences between hand eye coordination and reflexes?

    So when one catches a ball, they must have a specific level of hand eye coordination and reflex / reactions in order to be able to catch the ball. What aspect of catching a ball is related to hand eye coordination and what aspect of it is related to reflexes / reactions? How would having good hand eye coordination help with catching a ball and how would having good reflexes help with catching the ball? Or are they both one and the same thing without any differences?
  2. jcsd
  3. Aug 15, 2017 #2

    jim mcnamara

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    Staff: Mentor

    I am not sure.

    Let's give you some definitions.

    It is known that learned motions from lots repetitive practice - like practicing piano -- means that the cerebellum takes over from the cerebrum. In other words, you no longer think consciously about the movement. But that is not a reflex. Reflexes operate "outside" the brain, kind of like a short circuit. Example, when you touch a hot object with a finger, the muscles in your arm start pulling your arm back before your brain even gets the "hot" message from neurons in your finger.

    Someone else will have to tell you if and where reflexive motions (reflex arc is the term) can be created to take over from the above scenario with the cerebellum. If they do.

    I do not know.
  4. Aug 17, 2017 #3
    When the eye sees something that the brain intends to act on, and the brain sends the signal to the arm to catch the ball (hand-eye), it seems the time it takes to arm to follow those instructions and catch the ball would be "reflex". <<replace with the technical term there, but I think it's different from reflex arc that Jim is referring to? Because, in this explanation, the "reflex" is the arm's ability to move fast, as opposed to the time it takes for the message to get to the arm.

    So hand-eye = time for eye to see object, send message to brain, and brain to send message to arm muscles.

    And "reflex" (or proper term) = time it takes those muscles to actually catch the ball.

    If someone has uber fast hand-eye but slow "reflex" they may catch the ball at the same time as someone who has slower hand-eye but uber fast "reflexes".

    I'm using the word reflex in the common language term that people use when they say "Wow, he has really fast reflexes!" Again, no idea on the technical term for how fast it takes the arm to catch the ball once it receives the message, but in this case "reflexes" and hand-eye are two different things. And I'm unsure if reflex arc is the time it takes the arm to catch once it receives the signal, or if reflex arc is the total of both, but it definitely seems it is widely a two step process.
  5. Aug 17, 2017 #4


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    Neurologically, the term reflex is much more specific than the more common usage, which is fine for this discussion.
    Reflexes in sports etc. are much slower than many of the more well defined reflexes described in neurobiology (see below) and involve a lot of learned components.

    I knew a guy on a softball team I was on who played third base and had incredibly fast reflexes (for catching a ball that get to him rapidly after being hit). My hypothesis would be that he had an innate (somewhat hardwired) reflex to move his arm/hand up to block a rapidly approaching object (perhaps a protection reflex, probably through the optic tectum) which was linked to learned positioning his hand/glove for catching the ball (probably through the cerebellum). But who knows. We never stuck him with electrodes while he was doing this.
    I would assume most sports reflexes would be at least his complicated, probably more so.

    Neurologically speaking, reflexes are simple movements or responses triggered but simple stimuli, which usually occur rapidly.
    Rapid reflexes involve few neural elements and therefore cross few synapses (communication points between neurons) which is usually where most of the time delay occurs. They are often defined as not involving the brain, but there are many exceptions. They are (mostly) hardwired, not learned.

    The classic reflex people learn about is the patellar reflex:
    The patellar tendon is stretched (clinically triggered by a gentle tap on the tendon below the kneecap with a rubber hammer).
    This activates stretch sensitive sensory neurons which send impulses to the spinal cord (indicating the knee is being bent in an unexpected way).
    The sensory neuron endings end on and activate motor neurons that in turn signal the quadriceps thigh muscle to contract, which results in kicking out the lower leg.
    Normally, this would be involved in feedback for tuning muscle output to maintain proper leg position under differing loads.
    This only involves 2 neurons and 2 synapse (both chemical). Chemical synaptic delays are on the order of 2 ms. Action potentials, which transmit the signals over long distances along axons, go faster in larger and more myelinated axons for somewhat complex reasons (see myelin and saltatory conduction and cable theory).

    My favorite (because I have worked on it) reflex is the C-start reflex (in fish and amphibeans) which is an escape response to vibrational or contact stimuli. It involves sensory neurons projecting to the hindbrain and stimulating the Mauthner neurons (among others in the area). The Mauthner neuron has the largest axon in the body and therefore has the fastest axon conduction velocity. The Mauthner neurons strongly stimulates motor neurons on the opposite side of the body to fire, causing muscles on the side of the body opposite to the stimulus to contract, moving the animal away from the stimulus. Some of the synapses in this reflex are electrical synapses which bypass the relatively slow process of chemical synaptic transmission by making an electrical "fusion" of the pre- and post-synaptic membranes. This adds to its rapidity.
    This is considered a life preserving response for avoiding predators and has therefore been selected for rapid response times.
  6. Aug 17, 2017 #5


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    That would involve brain processing of the image of the ball on the retina, or rather a series of images in a matter of speaking for a moving object.
    Conversion of the focused 2d image information from each retina to a 3d image with depth or distance, continuously updated as the ball moves, extrapolation to a trajectory and velocity of the ball, coordination of signals to muscles telling how fast to move your legs, body, arm, hand and where spatially, with micro and/or macro adjustments being made along the way. There is a lot going on.

    I pulled just 2 sites about the visual part
  7. Aug 21, 2017 #6
    So what would you say is the difference in hand eye coordination when reacting to something (catching a ball) and when not reacting to something (sewing or knitting)? What are the different events that occur in the brain / body (hand & eye) during those two different activities requiring hand eye coordination?

    Can one have fast reflexes / reactions whilst having poor hand eye coordination (being able to catch a fast moving ball whilst having poor hand eye coordination)? How is someone's quality of hand eye coordination measured / determined? Is it based on speed? Such as being able to catch the fastest moving balls or controlling objects at a fast pace? So how about knitting and sewing where speed isn't a factor?

    It's quite complex!
  8. Aug 22, 2017 #7
    I'm not sure sewing or knitting really is a good example of speed of reflexes. A reflex is a non-cognitive response to a stimulus. There's no thought involved with the knee-tap, or the foot-swipe. Catching a ball on the other hand, requires training; which means you have to engage the brain in actually thinking about the motions needed. You can increase the speed and accuracy with training, but you never completely remove the cognitive portion. For sewing and knitting, in those two activities, the person sewing or knitting is usually drifting into a flow-state when doing a repetitive series of motions, and then out of it when they have to make a non-routine change in their stitching or knitting. Flow-state is not a reflex though. It's an optimization of mind and motion that results from complete familiarity with the motions being performed, intense focus of concentration on the task with a loss of reflective self-consciousness. Being in the zone also involves activating the pleasure center and modifies your time-sense. Depending on the motions you're performing, any disruption of that flow state will often cause your coordination to go all to pieces.
  9. Aug 24, 2017 #8
    (... indicates portions of quote I've deleted out)

    That is so fascinating! I hadn't even considered part of the reflex to be based on instinct, that's pretty cool and makes a lot of sense.

    I had no idea there were so many ways for the muscles to receive information. It seems clear that this stuff has been studied, but I'm kind of surprised that reaction in fish isn't the same as pulling your hand from a flame. Fish certainly react fast when you touch them!

    As for sewing and knitting being compared to catching a ball as far as an example of speed of reflexes, I think Tabillaristo's original question was about hand-eye coordination in general, which clearly comes into affect when knitting (at least if you want, clean, consistent lines!) And although the two at first might not seem comparable in regards to reflexes, having knitted before (and hating it ha ha) in my experience there are reflexes needed there too, especially considering it could take a week to knit a baby blanket, or a few hours, depending on how fast your reflexes are. Don't discount the skill of the motivated knitter! Maybe the biggest difference is the one Bill refers to above, in that knitting probably doesn't include any defense reflex mechanism.
  10. Sep 6, 2017 #9
    Yes, you'd be correct! Perhaps knitting wasn't the best example. However, my point was comparing hand eye coordination in an activity that requires a response to an external stimuli (catching a ball) vs hand eye coordination in any activity not requiring a response to an external stimuli (sewing maybe? or trimming someone's hair). What determines how good someone's hand eye coordination is on both these separate activities? As in, what different factors (if there is any) would lead to good hand eye coordination when responding to an external stimuli vs when not responding to any external stimuli?

    Based on some of the answers written, I'm guessing that for someone to have good hand eye coordination when responding to an external stimuli (such as catching a ball), their eyes has to see the object fast, send the information to brain fast and then transfer that information to the hand. However, in a situation where there is no response to an external stimuli, then what would be the difference? What factors would then constitute to someone having good hand eye coordination since there isn't any speed involved to reaction of a stimuli this time around?
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