ribbond our section on cognition by talking about decision-making in some ways you can think of a decision-making as being similar to what an individual neuron does an individual neuron pays attention to inputs from lots of different places inputs come in throughout its dendrites maybe onto its cell body maybe even onto its axon terminal it's going to integrate all of that information some of those inputs are going to be weighted more heavily if they're coming from farther back on a dendrites they're it's going to decay more those inputs are going to have less weight and then if they come in right by the axon hillock and it's gonna integrate all that information and ultimately the cell is going to decide if it's going to fire our action potentials or not and you can kind of think of the nervous system is behaving in a similar way so think about the decisions that you would be making an example would be what are you going to do on Friday night are you going to go to the party or are you going to study for your neurobiology quiz that's coming up and so there are lots and lots of different inputs that are going to be playing a role in that decision that you make you know are the cool kids the all the biology students are they going to be there as the person that really bugs you gonna be there how much studying have you done for your test what's your current grade when was the last time you went out and had some fun it might be worth a mental break right there's all sorts of things that go into our decisions and ultimately we integrate them all our physiological state our memories our ongoing stimuli right if your friends bugging you constantly to go go go go write all of these things we take into account we weigh them individually and then ultimately we have to make a decision now I'm like a neuron which has an axon hillock that essentially just decides when it gets to threshold to fire action potentials there's no real decision area in the brain the whole thing seems to be playing a role in making decisions now we're going to spend some time talking about individual neurons and their role in it and we'll also spend some time looking at different brain areas but ultimately there's no real decision area the closest thing that you could think of as being an actual sort of decision neuron would be a motor neuron right ultimately you haven't really decided until you've acted and so that might be the closest thing but we don't really think of there being a decision area certainly your prefrontal cortex integrates things and makes plans and it maybe oversees a lot of things but as we will see it's not always necessarily in charge of what's going on now the first thing that we're going to do is take a look at some really really simple types of decisions and look at the activity of individual neurons in those decisions and so when we study individual neurons it is beneficial often to simplify the kinds of behaviors so that we can control for various aspects of behavior really focus in on the decision itself that's what we're gonna look at to begin with here is something called a sensory motor decision basically an animal is trained to choose one thing or another I choose between two alternatives here labeled H 1 and H 2 and it's going to integrate information that's going to lead it to choosing one of those this information is typically the sensory input that's coming in in a noisy environment you might not know whether you see one thing or another and so as the the information accumulates you can ultimately decide whether you see a or B and that's the kind of experiment that we'll talk about here there's a lot of different models that go along with this this is a Samantha metric random walk e of a neuron maybe that's that's kind of chattering away and it's activity will start to go up if it's if it's thinking of seeing this stimulus it'll go down if it's thinking of seeing this stimulus you could have two separate neurons or pools of neurons one group that goes up when it sees one stimulus the other group it will go up if it sees another and whichever one reaches again you can kind of see it's similar to a neuron here a threshold first those will be kind of the ones that end up winning it's not super important to distinguish between these different models at this case but let's take a look at what some of the neuro physiological data show us about these types of simple decisions and what we're going to do is we're going to look at a sensory motor decision-making paradigm in which an animal is going to be observing a bunch of dots and those dots are going to be flickering around mostly randomly but the experimenters are going to add a little bit of of what we call sort of correlated motion within them so some of the dots aren't going to flicker randomly they are going to go from here maybe then to here and then a few more are going to go from here to here some of them are going to move as we say coherently and the more of the dots that move in the same direction the the more strong the percept is of motion and so what you will imagine is that you have these flickering dots and in some cases the dots will look like they're moving in a particular direction and in other cases they will not look like they're moving at all in some cases they'll be looking like they move in the opposite direction I can't embed this in your this video that I'm making but this particular YouTube link will show you a good example of what I'm talking about here the best I can do is embed a gif so here's a random motion random dot motion stimulus if you look at it you can maybe see that these dots appear to be maybe swirling around they actually are don't have any embedded motion in them but you can imagine that if some of these dots were we're going together that you would imagine you'd be able to see motion again check out this video for a better sense of what's going on here so what scientists can do is train an animal to take a look at this motion and they can either make the dots completely random in which case there's no motion strength at all or they can embed some small amount of real motion within there and it's a hard decision but the animal will ultimately know which which direction that's going in or you can make it fairly obvious and have most of the dots or half a dots all going in the same direction and then the animal is pretty good at it and then the animals job is to make an eye movement to a target towards where the dots are going and so in the case of different motion strengths if there's no motion whatsoever the animals basically just sort of guessing but in the case of these other two the animals going to know ultimately which direction the dots are going and it's gonna get pretty good at detecting that motion now let's take a look at a couple of different neurons here from a couple of different brain areas thinking back to the parts of the brain that are going to be involved in detecting motion we have parts of the brain in the dorsal stream very famously in the monkey brain we have an area called Mt these cells are responsive to directional motion and what we see here is that this particular cell over the time at which the motion stimulus is being displayed it's going to have sort of a medium amount of motion here in the blue if there is no motion in the direction that it prefers so these cells have a direction that they like and it's going to have a slightly higher amount of activity if the motion strength is medium and it's gonna have really high activity if the motion strength is nice and high and you actually get the opposite it decreases as to activity if the motion is in the opposite direction to what the cell like so basically this cell is just saying that it sees motion in its preferred direction and it scales with the strength of the motion stimulus it's a pure sensory response it's just telling the brain hey I'm seeing this amount of motion right now and it continues just to say that because the student doesn't change it's just the same kind of flickering dots with some percent of coherent motion now if we look at some of the brain areas that MT project to MT actually sends axons into another part of the parietal cortex lateral intraparietal area which isn't both involved in visual processing but also in making directional eye movements and what we see here is something different instead of just sort of having a linear unchanging firing rate in response to the unchanging stimulus these neurons actually seem to accumulate evidence they ramp up and up and up and the more evidence that they have meaning the stronger the motion strength the faster they ramp up and so when there's really no motion ultimately the guy has to decide any way so that the ramping up of this evidence goes up slowly in the medium case in the red line here it goes up with a medium speed and when the evidence is really strong it ramps up really quickly it's almost like it's just doing a mathematical integration operation on this data here and when it gets to and so this is all aligned to when the motion starts so everything all the neural data here is sort of aligned here if we look farther on in time and we align everything to when the animal makes its response we see that in every case every case here that these cells are responding to one kind of motion strength or another when the motion strength gets to a particular threshold the animal makes his eye movement and then these cells stop firing so this is pretty much a direct example of that kind of threshold model where cells accumulate evidence over time and eventually reach some sort of threshold at which they make a decision and then these cells are pretty close to the output they're close to being motor neurons they're not directly controlling the eye muscles but they're pretty far along in that sensory pathway we see the same thing here if we instead of breaking down the trials by motion strike we break them down in terms of the animals reaction time when the animal is really quick you can see that the activity ramps up really really quickly and when the animal is making his decisions more slowly as if he's not quite sure of himself or it takes longer for that evidence to integrate you can see that the slope of that is a lot less so this is the kind of thing we see at the level of individual neurons and you can make a lot of hay studying decision-making in these really really simple simple forms what we're gonna do now is move away from individual neurons and start talking about what we see at the level T of the whole brain we're gonna look at human brain imaging studies and one thing to keep in mind about this is that these studies are are difficult to do and none of them are super definitive this is a relatively new field and the data don't tend to be quite as cut and dried as they might in a neuro physiological experiment so the individual studies that we'll be taking a look at are sort of classics or exemplars they may or may not be fully true they may or may not have been replicated over the last ten years or something but in general I think you can you can generally agree that the main ideas that we'll be talking about here are probably relatively true right the HAR the farther into human cognition we get the more difficult it is to sort of teach definitively about it so take everything with a grain of salt but understand that you know when we start talking about like emotional parts of the brain versus thinking parts of the brain that seems to be a reasonable if messy dichotomy that that tends to hold even though if you're an expert in the field you can you could say a lot of complicated things about it so none of these experiments are super definitive but they're all generally along the right right path and so what we all do is take a look at a number of different experiments sort of classics in the field and take a look at what's happening in the brain while we're making this and the first thing I'm gonna highlight is the role of emotion in decision-making because we often think of humans as being or the decision-making apparatus in our brains as being driven by our cognition or driven by our prefrontal cortex the planning part the part of our brain that is sort of rational and logical but you know observing human behavior makes it very clear that that's not always the case and so what we're gonna do now is is sort of contrast these areas and take a look at both the role of more sort of cool rational dorsal lateral prefrontal cortex types areas with parts of the brain that have to do with emotion and the example that we're gonna start with is taking a look at a well known bias in human decision-making called the framing effect basically what this says is that depending on how you frame a question people will respond differently so very very simply if you give someone an option and you frame their choice as getting something they're much more comfortable with just taking that if you give them the option and there's a loss involved you frame something as being a loss they're much more likely to want to avoid that they're much more likely to actually try to gamble in order to avoid a loss so people are comfortable getting a gain and don't really feel the need to sort of gamble a chance to get a bigger gain or something but when you frame something as a loss they're much more likely to gamble even if the choice is exactly the same so here here's an example here's the way this experiment was run and people were doing this game in the scanner and they would literally get paid depending on on how the game played out for them - based on their decisions and so in one type of trial called the game frame they were told okay you're gonna receive fifty pounds that was now here's the choice you can either keep 20 of it or you can make a gamble and here's your gamble the slice of the pie is essentially your percent chance of getting this and you can either keep your 20 or you can gamble with a more than 50/50 chance of losing everything or you can have this amount of chance of keeping all 50 right and so the choice is am I going to keep my 20 the sure thing or am I going to gamble to win it all even though that's less likely so this is the game frame because of the 50 years is told you're gonna get to keep 20 the status quo is that you keep 20 the loss frame is exactly the same thing you are given 50 the sure thing is that you lose 30 you can have the same gamble but notice that it's been framed in a different way whether you lose 30 or gain 20 out of the original 50 is exactly the same thing those two circumstances the gain frame and the loss frame here are exactly the same question the exact same scenario just one is written in a different way and what we see is that people are way more likely to gamble when the option is framed as a loss and that's what we see here when we just look at the behavioral data so over here this is the percentage of trials in which the subjects decided to gamble and they were much more likely to gamble when it was framed as a loss than it wasn't a game and of all the 20 subjects they had they could calculate sort of what they called a rationality index it was a subjects propensity to gamble more often in the loss case than the game gain case and every subject was above zero in this meeting every subject was affected by this some subjects not so much some subjects a lot more but every single subject in in the pool here was affected by this this framing of it again there is no difference in these in these two cases the way they accept this stuff the only difference is how its framed your unrelated to the the study is are these gratuitous three dimensional bars on on this plot that are just right out don't do that okay now what do we see in the brain while people are making these decisions well very very interestingly if we look at the left and right amygdala an emotional part of the brain associated with fear we see that the amygdala was active when people were in line with the framing effect which meant that they were gambling when it was framed as a loss it also meant that they were taking the sure thing when it was framed as a gain both of those are sort of under the influence of the framing effect or in the direction of the framing effect but even if we're just looking at the times that they gambled the amygdala are more active when you are under the influence of the framing effect if you are not acting in accordance of the framing effect and again people don't do this a hundred percent of the time then this part of the brain was actually less active than normal well what about more rational parts of the brain the orbitofrontal cortex which we know is involved in emotional processing but also as part of the frontal cortex what we saw here is that the rationality index of the subject the graph that we saw earlier helped affect that each subject was by the framing effect was correlated with activity in the orbitofrontal cortex the more activity in the orbitofrontal cortex these subjects had the more rationally they tended to behave so here just as the general take-home message it seems like there are a couple of different networks in the brain that might be competing with each other that are both sort of trying to contribute to decisions one that is more sort of easily biased more emotional that would be represented by the amygdala and acting under the influence of the framing effect and the more rational part of the brain the frontal cortex not being influenced by the the framing effect because the framing effect should have no bearing fashion okay we can take a look at emotions in another interesting kind of decision-making well studied over the last 15 10 or 15 years is moral decisions how do people make moral decisions how do we decide what is right what is an okay thing to do and there are a couple of really really famous thought experiments relative to this these are sort of the cartoon versions you can you can ask people all sorts of similar questions and get similar answers but this is the sort of the classic pair of them the first of the two is called the trolley dilemma and it involves this poor guy here and then these even worse off people tied to the train tracks and so the the scenario the contrived scenario is that this trolley is going to come along and run over these five people the only way to stop the trolley from killing these five people is for you to pull the switch which will shut the car off onto this other track where we'll only kill one person and so you ask people is it morally okay to pull this switch and to kill this person in order to save these people most people say yes it is not everybody but most people generally say that it is okay to pull the switch to save this person now an alternative version of this is called the footbridge dilemma and it's even more contrived in this case the trolley is going to run over the five people you are standing on top of a bridge next to this very large person here and the only way to stop this tram and it's guaranteed to work you know it will absolutely work as but if you push him off onto the path of the train and he will be killed and but the train will stop and you will have saved these people and so you ask people isn't okay to push this man off and what you find is that most people say no now you may might do the math here and find that when your calculations are done running in both cases you have killed one person to save five and yet people respond or tend to respond very very differently to these most people say this is okay most people say that this isn't the idea here is that in one case you are not directly killing someone we call this the impersonal case in this case when you actually have to touch someone you were actually physically pushing them into the path of danger we call that the personal case and people treat those very very differently even though rationally there is no difference ultimately between them again this is a super contrived set of problems you can make better ones that aren't quite so pokey but in general when people are in personally involved they're more likely to approve than if they are personally involved in doing it so you can give people while they are in the brain scanner a bunch of these different dilemmas and you can split them into moral personal versus moral impersonal the kind of where the outcomes are exactly the same but is it you that's physically doing the the bad thing and what you see is that in areas associated with emotion you get a mega activity of those brain areas when people are considering the moral personal cases right those personal cases activate our emotions which we think probably gives rise to our hesitancy to engage in them right they just seem emotionally that even again rationally they ultimately lead to the same outcomes in terms of areas associated with working memory we see that they are more active in the moral impersonal ones in fact very similar activity to a sort of non moral judgments like should I get milk or should I get cereal or you know something like that that's not and doesn't have a moral aspect to it so yet again another example of two systems within the brain that whose activity might lead to different outcomes under different circumstances an emotional part of the brain and a more sort of thoughtful or rational part of the brain let's expand our discussion of moral decisions by bringing in another idea and this is the ability of people to put themselves into the mind of someone else to understand what they're going through and what they are thinking of we call this the theory of mind to be able to put yourself into someone's shoes and anticipate what they would they might be thinking and why they might be behaving the way they are and we can use this to take into account how people make moral judgments so here's an interesting experiment again done in an MRI scanner people were given a number of different scenarios like this and then are asked about it essentially on a scale of is what happened that the person what they did is it permissible right is that okay to do or is it forbidden is it let's take a look at this particular example so grace and her friend are taking a tour of a chemical plant as one does when grace goes over to the coffee machine to pour some coffee her friend asks for some sugar in hers the white powder by the coffee is just regular sugar because the substance is in a container marked toxic grace thinks it is toxic and she puts the substance in her friends coffee she is trying to kill her friend her friend drinks the coffee but because it was just sugar it is fine again it's kind of a contrived thing but the subjects are asked is what grace did okay so think about it her friend was fine was grace okay in dumping what she thought was a poison into her friends coffee most people would say that that is forbidden and not permissible and that is because we take into account theory of mine we take into account what other people are thinking we think Grace's friend by reading this wanted to kill her friend and thought this would be a good way to do it and we think that her motivations were forbidden so what you can do is you can ask people all sorts of versions of these types of scenarios and you can mix them up on two different axes so you can mix them up on what the person thinks so you can tell this story where grace thinks it spouts it's the powdery sugar right she just wants to get give her friend sugar in her coffee right or you can tell the story where grace thinks it's toxic so you could switch things up on that axis and then you can also look at the outcome right if it is just sugar and it is toxic well her friends gonna die is Grace at fault here she thought it was sugar right here's the condition that we saw before she thinks it is toxic but her friend is actually fine and so we could ask people different combinations of scenarios like this and see what happens generally what we find is that people really really do take into account more than the outcome the belief right if grace thinks she's poisoning her friend even though her friend is fine we really don't think grace was was was doing something that was okay and that's shown in the results here so this is a behavioral experiment and basically what you see is that when people had a neutral belief and a neutral outcome well everyone says that's hunky-dory that's fine if people had a neutral belief and a bad outcome like she thought it was sugar but her friend died people are still generally okay saying that that is permissible permissible and you get a little bit of less permissibility just because the outcome is bad maybe she should have been more careful in a chemical plant who knows exactly why but what people really don't like right are the negative beliefs when people have the negative beliefs they are much more likely to say you know that is forbidden regardless of whether the outcome was neutral or not okay so that's the behavior what this particular experiment did was very very cool very very clever they're essentially what they're gonna do here is bias people's moral judgments by stimulating or in this case deactivating a particular part of the brain the part of the brain that we're gonna look at here is circled in red it's the temporal occipital all right temporoparietal Junction it is actually near both the junction of the temporal lobe the parietal lobe and the occipital lobe but we know from many many years of experiments that this part of the brain is really really important for theory of mind this part of the brain is really important when we're thinking about what someone else is thinking about now what the experimenters did is they used this technique transcranial magnetic stimulation positioned above the temporal parietal junction with the particular stimulus parameters that are known to inhibit that part of the brain so they could essentially turn this part of the brain off and by turning that part of the brain off the part of the brain involved in thinking about what someone else his motivations are they were able to bias people's moral judgments this to me is fascinating we think of our moral judgments as being sort of written in stone unaffected by something that is Who I am just with a very very subtle change in in in using a magnetic stimulator you got to sit very still so you can't really do this to someone who's walking down the street but if they are willing to sit still for you you can you can subtly bias their moral judgments people were significantly less likely to say something was forbidden in the case of a negative belief in other words if the outcome was okay the belief didn't matter quite as much so if grace thought it was poison but if the person was okay people are subtly more okay with that even though the person did believe that they were trying to harm them they have been subtly altered to be just a little bit more okay again it's not a super dramatic effect it's not way up here where it's like yeah no problem but you can subtly alter people's moral judgments again something that seems really foundational to our own personalities and our how we see the world can be altered experimentally which is something I find really really fascinating now you can essentially turn off part of someone's brain right using transcranial magnetic stimulation do you need something as sophisticated as TMS to turn off parts of people's brains the answer is going to be no you can turn it off just by talking to them so let's talk about a cool experiment where we see this the experiment that we're gonna be looking at here was done in Scandinavia which is a really really secular country where they have a real large proportion of non-religious people so what they did is they recruited half their subjects as being Christian subjects and half of their subjects as being non-religious subjects and they had everybody listened to 18 different prayers and they were told that the prayers were either given or recited by a non-christian person or they were recited by a Christian person or a third of them were recited by a Christian who is known for their faith healing abilities so this is someone who's who's was probably like a super super super Christian it turns out of course that because this is a psychology experiment that the prayers were actually all just read by regular Christians and they were just completely randomized so there really was no faith healers or non-christians they were just essentially control they're all basically similar okay so they had these different groups of people half Christians half non-religious listening to these these religion items these religious prayers and they were thinking that the subjects were told that the prayers were being delivered by three sort of different levels of religion right so low low religion the non-christian medium religion and then the high religion person would be the faith healer and they had to do two things they had to listen and then they had to rate how charismatic each speaker was and so ultimately this this experiment is not about religion it's about listening to people you agree with and rating people in terms of charisma and seeing what goes on in your in your brain so this particular example comes from a country where they could divide people in this particular way but the the results aren't particularly to religion or anything and of course they recorded their brain activity while they were listening to these different prayers so what do we see well first of all in the half of the subjects that were non-religious there was no difference in brain activity across the three different levels of religion reciters they didn't care whether the person who they thought who was reciting the prayer it was was told that they were non-christian Christian or faith healer that didn't have any effect on them because that's not something that their brains are right attune to or that they care about what was interesting instead was the Christian subjects the Christian subjects when we look at this particular part of the brain here in the prefrontal cortex or this area up here in the temporal parietal area again part of the brain involved in thinking about other people and what they're thinking we see in both of these cases there was a decrease in activity going from when they were listening to who they thought were non-christians to when they were hearing people who they thought were extra super healing Christians these parts of the brain these sort of cognitive parts of the brain involved in planning and assessing were essentially turned off turned down reduced in activity when they thought they were hearing somebody who was super super religious and they also rated them as being more charismatic so this is how charismatic they found them and there was a reduction in both of these brain areas activity not just with the group but with how charismatic they rated the person as being and the idea here is is that you don't really need transcranial magnetic stimulation to turn people's brains off you turn people's brains off by being charismatic you turn people's brains off by telling them what they already want to hear or being part of the group that they're in and like I said this isn't just particular to religion this happens to be the experiment that was done we are all affected by this I am affected by it you are affected by it it is probably one of the the most useful things that take away from this class is knowing that you you you you and me are affected by this and just knowing that helps us be a little bit more on guard but when people are telling you something that you already want to believe the thinking parts of your brain they are going to be less active and that's not good the thinking parts your brain I would recommend be active maybe especially when people are telling you something that you already believe or already want to know so this I think is a really good example for for showing how you know brain activity can be suppressed without any sort of fancy equipment just by telling people what they want to know and again these were not actually faith healers we're just told they were of faith healers so the more charismatic someone is maybe the the more you should put your your thinking cap on and the more skeptical the last thing going to talk about is consciousness and its role in decision-making we're not going to spend a lot of time talking about consciousness in neurobiology it's a real difficult subject to study but we can look at it in the context of making decisions and the first thing we want to look at is what we already know about our conscious awareness and a lot of what we know about it comes from something we call split brain research split brain research comes about from a surgery that was done more commonly decades ago but still occurs every now and then in patients with epilepsy epilepsy typically starts with a small group of overactive cells actually it's typically in the temporal lobe those overactive cells start firing and start activating their neighbors and then the the wave of excitability sweeps across the brain and eventually it can sort of override the whole brain and sort of cause the entire brain to be active causing seizures of one kind or another now typically these days they're treated with drugs inhibitory drugs that can sort of essentially calm cells down when that no longer works you can go in with focal lesions and you can go in and sort of burn away with electricity a small the small group of cells called a focus where where the activity starts problems can occur if that surgery doesn't work or if the the epileptic focus happens to be like in Broca's area or Verna Keys area apart that's that's really critical for language it is better not to destroy that part of the brain and so sometimes an alternative is to cut the corpus callosum and what we call a split brain surgery and so in this case the Saida tory waves are limited just to one hemisphere and so this is kind of a last-ditch effort to cure skits are to cure epilepsy now studying people who have had this procedure done is very very enlightening what's really interesting is that people in the first day or so after their their surgery are really disoriented they're uncoordinated but it doesn't take them long essentially to be fine and to normal observation seem to have no difficulties whatsoever it's not until you really sort of get them in the lab that you can really really start to see how different parts of the brain are involved in different types of processing and different hemispheres of the brain are differentially involved in our our conscious perceptions so it's probably a good time here to talk about something that you've probably heard of many many times in your life a difference between the left side of the brain and the rights of the brain I haven't necessarily been spending a ton of time on it in the class because it's it's fairly complicated the kinds of things that you hear in school are mostly super oversimplified to agree that's even more simplified than the kind of stuff that we're talking about here but there are a couple of things that are fairly consistent in terms of lateralization of things the left hemisphere at least within right-handed people is almost always the dominant hemisphere for language so when we talk about Broca's area for a Niki's area in the vast majority of people 95% of people those areas are in the left hemisphere for people who are left-handed we actually see that people who are left-handed have less differences across the brain they have less lateralization of function and for left-handed people the language is about 5050 between the left and the right hemisphere so things are a little bit more miss mixed map mismatched or mixed up in people who are left-handed left-handers make up about about 10% of the population now what's really interesting is that because language generally resides on the left-hand side of the brain we can do some really really interesting experiments here's an experiment where somebody is holding an object behind a screen that they can't see and then they are asked about it if they hold it in their right hand now remember the right somatosensory cortex gets information from the left side of the body and the left somatosensory cortex gets information from the right side of the body if the person is holding the object in their right hand they can tell you what it is if they hold it in their left hand they cannot name it right the idea here is that the information goes to the right side of the brain there is no way to tell the left side the language side of the brain about what the left hand is feeling and so the right or sorry the left side of the brain cannot name the object the same is true with vision if you show an object's name in the left hemisphere the left hemifield is represented in the right occipital cortex if you show it here on the left the person will not tell you that they saw anything right they will say I did not see that that part of their brain didn't see it even though the right side of their brain saw now what's interesting is that if the left so the right side of the brain sees the word ball and the left right so the right side of the brain sees the word ball and the right side of the brain has control of the left hand the left hand can pick out the ball from a group of shapes the right side of the brain saw the word ball the left hand controlled by the right side of the brain was able to pick the ball out but you asked the person did they see the word ball or have any idea why they picked up a ball they would say I don't know the two sides of the brain under these experimental conditions where the subject is staring straight ahead right have been separated now the right hand the right side of the brain the right hemisphere is usually better at spatial tasks so here's a good example of this you ask somebody to replicate a pattern that they see here on a piece of paper using these blocks where they've got different colors on the blocks the right hand activated by the left side of the brain has trouble doing it the same person has no problems doing this spatial task with their left hand in this case the eyes are free to move wherever it's literally just the the hands being driven by those particular areas of the brain sometimes you will see in conditions like this where the subject is struggling with their left hand the right hand will sometimes try to to help out you sometimes hear from people who have undergone the split brain procedure that that every now and then in their day-to-day life their hands will kind of be doing different things or one will be reaching for one item of clothing on the shelf and the other one will be reaching for something else as if they almost had minds of their own typically these things don't end up being debilitating but they these people do notice those types of things throughout their day-to-day life now you can do some very very interesting experiments with split brain subjects this one is really really cool in this particular experiment you show somebody who's who's fixating here so you show their left and right visual Hemme fields to different scenes on the left here which is going to go to the right side of the brain here you show this winter scene and again you can there are lots of different versions of this and on the right you have this chicken foot and that's going to go to the left side of the brain now the subject is told to point to the object that they saw and so what this person is going to do because you you gave them the instructions verbally and they sort of have conscious recollection at least the part of their brain that can talk about it think about I'll let you think about this which of these two stimuli are they going to sort of have conscious recollection of if you told them to point to something associated with what they consciously saw which of the two things are they going to point to they are going to point to the chicken initially because the left-hand side of the brain which has access to language and is going to sort of have conscious recollection of this I was gonna say yep I saw a chicken foot and so I point to the chicken and that's what will happen now you asked them with their other hand go ahead and point to something else in this range of items that you think might have something to do with the scene that you saw now again they're gonna tell you they saw a chicken foot and nothing else but what they do is that particular hand driven by the right hemisphere which saw the winter scene points to the snow show now what's really interesting is that of course they will do this they'll have no recollection of the scene they won't know why they picked this but you ask them why they picked it and in this particular example is the one that's always in the textbooks because it's it's amusing is that the subject says well yeah I picked out the shovel because that's what you use to shovel out all of the droppings in the chicken coop that must be why I pick the shovel even though you can see of course the shovel very obviously goes with the winter scene the language part of the brain had no conscious access to that information so it had to make something up it literally was making something up rationalizing why the the right hand had made the decision that it had and again the right hand is essentially making a decision unconsciously is making the correct decision right it's picking the right object here but when you ask the person their output has to do with chickens because that's what the left side of the brain saw so fascinating stuff there are lots and lots of things that of course going on in your brain that are outside of your conscious awareness much of what your decision-making is is almost certainly underneath the level of your brain that is sort of consciously aware and this kind of experiment really sort of drives that home another really cool experiment this one is purely done behaviorally shows that something is as sort of fundamental as our own internal motivation is in at least in some ways can be altered subconsciously so here's a very simple experiment the subject is essentially told to squeeze a squeezy bulb hand dynamometer as a force transducer they squeeze it and it'll a little thermometer will tell it tell them how hard they're squeezing and they just have to squeeze as hard as they can but there are a couple of different conditions they are shown either a penny or a full euro which is over $1 worth and that the coin that they see either a euro coin or a penny coin is going to dictate how much money they get as a function of how hard they squeeze so if they see the full euro and they squeeze a hundred percent they'll get the full euro if they squeeze as hard as they can a hundred percent they'll get a hundred percent of a cent if they saw the same and so the different motivations are monetary you're obviously going to try harder when you're your earnings are going to be a hundred times as much yeah they're 100 cents in a euro and you're not going to try as hard of course when the payoff isn't anywhere near as good so that was one manipulation make it either show one cent or a euro the other stimulus was was was was a mixed was scrambled so they couldn't interpret it the interesting manipulation was here they either showed the coin stimuli for 17 milliseconds which is too fast for someone to be able to tell which coin was scrambled in which coin was the real coin that was a sense essentially below your conscious awareness or they showed it for 117 milliseconds which is long enough for someone to say yep I noticed that that one was the euro yep I noticed that one was the the penny and then after this coin stimulus came on they were asked to squeeze the bulb for as hard as they wanted and the harder they squeezed it the more money they got but they got a hundred times more money if it was the euro versus the penny and so people were more motivated to to squeeze hard when it was the euro so let's take a look at how hard they squeeze the ball what we see is that when the stimuli were fully visible and made it to conscious awareness people basically squeezed up twice as hard when it was a full euro than when it was as a penny so that's not super surprising we can imagine if that's the case what's really interesting is that in the subliminal non-conscious stimulus there was no difference in the case when the visual stimulus indicating the coin was on the same side as the hand that was squeezing which means that was going to the opposite hemifield right which actually means that it's going to the opposite many feel in that case there was no difference the subject really had no either conscious or unconscious awareness what was really interesting the main cool thing from this paper is that when it was shown on the opposite high side meaning the same hemisphere was getting the visual input and controlling the motor output right intra hemisphere occur within that hemisphere the vision was on the opposite side but the the stimulus and the motor output were within the same hemisphere subjects squeezed harder when it was the euro right they were altered by a stimulus that they couldn't actually consciously perceive so your motivations can be driven subconsciously now this isn't necessarily meaning that you know like subliminal advertising works or something I'm not sure what what the data are on on that I'm guessing it's it's not as effective it's just like very obvious advertising because obvious advertising works really well but you can change people's motivations and again not massively not as much as something that's perceptible but you can alter people's behaviors even when they don't know about it right there their intrinsic motivation to do this work has been changed under the surface now neurophysiological II what do we see when when people are making decisions and and what evidence do we have that things are going on before people are sort of consciously aware of their decisions this is a very famous experiment done many many decades ago looking at EEG activity and what you see is you have people making decisions and they are able to report when they make the decision so their awareness of the report occurs here and then they act right here you actually see neural activity EEG activity start to ramp up many many hundreds of milliseconds before the subjects are even aware of when they intend to make a decision right so they are aware of their decision about 200 milliseconds before they act on it but the EEG activity actually rises a lot before that this particular signal out here has been called the readiness potential actually sort of a subconscious ramping up of your brain activity that leads to what we think is a conscious decision and finally here's a another experiment that was done doing the same kind of thing but looking at MRI signals and so people just see a bunch of letters and at any time while they're just sort of looking at these letters which are literally irrelevant to the task they can decide to push a button left or right button that they have at their fingertips and then they are asked after the button has been pressed hey which letter was on the screen when you decided which of your fingers you're gonna push and when you're going to push it so people are freely deciding to act kind of whenever they want and they report oh you know here's the letter that was on the screen when I decided to do this now what you can do is you can go into the brain and you can use brain activity to essentially predict which response the person is going to make you can yeah use brain activity to to determine whether the subject press the left or the right button and what you see is if you look in the motor cortex right you see the brain activity in the motor cortex is differential between left and right fingers basically the choice after the decision has been made right so that's this red line here and we see that these two brain areas the supplementary motor and primary motor cortex their activity occurs sort of after the conscious decision has been made pretty much in line with when the actual motor output is is made when the muscles are contracted contrast that with activity in the frontal cortex and here in the cingulate gyrus activity in these brain areas can predict which of the two fingers is going to be used and when up to eight seconds before the person actually makes the decision there is activity in the brain that is correlated with an upcoming decision many seconds before that decision is actually made and so the take-home message here is again that the activity even of our sort of rational frontal parts of our brain that are making conscious and maybe even rational decisions is still very wet very likely to be made sort of under the surface at a subconscious level just another reason to to sort of often but not always stop and think about decisions not to the extent that you you agonize over them but paying attention and and using using your brain appropriately is generally thought to be a good thing