作者：Ben Lewis-Evans

几周前当我在听某一游戏播客时，主持人在描述一款特殊游戏时说到这“刺激了多巴胺”，即关于他们在体验游戏时感受到种种乐趣，并希望继续游戏（游戏邦注：多巴胺是一种神经递质，如大脑中的化学物质）。该评论是即兴的，但却反应了一个常见的观点——释放多巴胺是关于乐趣和奖励，因此这与游戏玩法息息相关。但是该观点是否正确？

如果回到30多年前，研究人员将会呈现出多巴胺是关于乐趣和奖励的的观点。更早之前有一个关于该理念的实验，即在老鼠大脑上安插电极去刺激大脑领域对多巴胺产物做出反应。这些老鼠可以通过按压杠杆去表现大脑受到刺激。为了反应这种自我管理的大脑刺激，老鼠将牺牲一些基本代价去按压杠杆。例如，比起吃，社交，睡觉等等它们更愿意按压杠杠。再加上之后的其它证据，这部分大脑领域被标记为“愉快中枢”，似乎也很有说服力。

所以那时候的结论便是，多巴胺是让我们喜欢奖励，并鼓励我们去追求奖励的最重要化学物质。同样地，主持人当下也传播了有关多巴胺作为一种奖励和乐趣的化学物质的理念。

不幸的是（不过在长期看来却是幸运的），大脑并没有这么简单。科学一直在发展着，所有的事物也都在发生改变。而该领域的主要研究者建议关于“多巴胺能做什么”的最佳答案是“混淆神经系统科学家。”

虽然该答案很有趣，但却不能帮助游戏领域中的人更好地理解自己的游戏是否能够影响玩家的大脑。同样地，对于我来说撰写本篇文章的目的便是为了解释当前的科学对于多巴胺所扮演的角色和奖励的影响。此外我也会尝试着根据这些神经递质对于游戏创造者的意义而提供一些相关评论。

需要注意的是，在接下来的内容中我将专注于谈论多巴胺（神经递质）本身的效果，而不会谈及有关大脑领域中有关成果或抑制等内容。同时我也会专注于讨论最重要也是最有趣的例子和实验，所以这并不是针对于某一对象的学术评论。

喜欢，学习或想要获得奖励

处理多巴胺问题及它能做什么的一种有效方法便是根据喜欢，学习或想要去分解人们对于奖励的反应。也就是说，当提到你对于奖励的反应（如在游戏中获得某些内容）时，你是单纯喜欢奖励（如它很有趣），掌握了适当的方法去获得奖励（如你能否真正地玩游戏），以及你是否愿意努力获得该奖励（它是否能够刺激你继续游戏）都是完全不同的内容。

喜欢游戏

如果你为了获得某一奖励而有所付出，你便会喜欢该奖励。这便是引导着早前的研究者做出多巴胺与乐趣（“喜欢”）相关的假设的主要原因。基本上来看，他们认为如果老鼠感受不到乐趣的话又怎么会长时间去推动杠杆呢？

关于自我刺激的老鼠的理念是一种可理解的假设。虽然最终证明人们通常都很喜欢奖励，但是为了能够有效改变行为，它们不需要获得人们的喜欢，况且多巴胺本身并不会直接包含于“喜欢”和乐趣中。

随着研究的发展，我们越来越清楚动物也具有自己的能力去创造多巴胺，所以即使它们的多巴胺释放被阻碍或限制（通过药物，手术或遗传），我们也仍然能够证实这些动物“喜欢”某些事物。就像一只因为基因转变而不能释放多巴胺的老鼠它也仍会对糖水或其它食物表现出偏爱。因为这些老鼠喜欢甜味的水，所以在能做出选择时便会略过没有甜味的水。此外，你可以通过遗传工程赋予变体老鼠额外的多巴胺，而这些动物不能呈现“喜欢”不同食物的任何额外标记（尽管在它们的脑子里也充斥着所有的多巴胺）。

这是关于老鼠，那人类呢？研究人员并不能创造变体人类，他们也很难将直接在人体上试用药物或做大脑手术。但是我们可以观察帕金森患者，这便是受到多巴胺生产问题的影响。这些患者与老鼠一样，在对于奖励（如甜味）的喜欢方面也不会发生改变。

考虑到上述的发现以及其它相关内容，研究人员很难继续坚持多巴胺是一种乐趣或“喜欢”化学物质的理念。实际上，在1990年，一名主要的研究员同时也是多巴胺与乐趣息息相关这一理念的主张者Roy Wise便声明：

“我不再相信乐趣的分量与充斥于大脑中的多巴胺数量是均衡的。”

的确，比起多巴胺而言，像类阿片和大麻类等其它神经递质更加贴切“喜欢”奖励。尽管我们也需要注意在大脑中释放类阿片可能间接导致多巴胺系统做出反应，这也再次解释了之前关于多巴胺角色的困惑。但是就像之前提到的，从遗传角度来看老鼠不能在创造出多巴胺后仍喜欢某些事物！

所以你在游戏的时候是否感受到了愉悦？也许多巴胺并不是创造这种感受的原因。同样地，如果有人告诉你他们的游戏是围绕着扩大多巴胺传达进行设计，那么这便不能代表他们的游戏就一定是有趣的。

学习游戏

如果多巴胺并不是关于乐趣，那么它能做些什么？还有另外一种假设（在20世纪90年代开始盛行）是，多巴胺将帮助动物学习如何且在哪里获得奖励（这是在游戏中同时也在生活中需要记得的非常有帮助的内容）。当科学家开始注意到多巴胺活动会在奖励传达前开始提高，从而帮助动物预测到未来奖励这一情况时，这种假设便开始出现了。换言之，当动物之前看到某一刺激与奖励是相互维系在一起时，多巴胺便会被释放出来，从而预测到即将到来的奖励，而不是作为奖励本身的反应。似乎当奖励是不可预测时（就像游戏中随机掉落的奖励），多巴胺系统中的活动便会增加。如果多巴胺是关于学习，那么当动物期待或掌握了一个不可预知的奖励可能出现时，多巴胺活动便会增加。毕竟，如果奖励是不可预知的，你便会投入更多关注/尝试并了解相关奖励标记，从而找出在之后获得奖励的更有效的方式。

再次，虽然有关多巴胺扮演的学习角色的证据也非常合理，但是变体老鼠也再次动摇了这一理念。在有关该领域的某一研究中，华盛顿大学的科学家发现，不能再释放多巴胺的老鼠不仅仍会继续“喜欢”奖励，同时它们也还能学习到奖励来自哪里。也就是这些变体老鼠在接受了咖啡因的注射后仍能掌握奖励是在T形迷宫的左手边。注射到老鼠体内的咖啡因是与多巴胺释放无关的，但却是需要的，因为如果没有这些咖啡因，那么不能释放多巴胺的老鼠便什么都做不了。实际上，这些变体老鼠会因为缺少足够的食物和水而死亡，除非你能够向它们定期注射药物而储存它们的多巴胺功能。

除了上述的实验，当提到学习时，老鼠释放了比往常更多的多巴胺并不能证实它们拥有更多优势。但是就像之前提到的，缺少多巴胺的老鼠会饿死则意味着多巴胺具有一定的作用。但如果多巴胺既不是关于获得奖励的喜悦也不是学习如何获得奖励，它又能做些什么？

想要（渴望，需要）游戏

基于现在的科学，似乎多巴胺与想要奖励更加贴切。这并不是一种主观感受或像“我想要在今晚完成《黑道圣徒IV》”这样的认知声明，而是一种获得奖励的动力或愿望。所以这并不是关于“喜欢”和乐趣的感受，而是推动着我们去做某事的需求或动力。主观上来看，这就像你今晚不得不在停止前于《文明》中再玩一轮或在《暗黑破坏神》中获得更多战利品。当讨论到老鼠实验的结果时，有些研究人员认为多巴胺创造了一种“吸引力”或强制力推动着对象去获取奖励。的确，有人会认为多巴胺扮演“学习”角色的证据只是“想要”获取一个未知奖励的标志，并因此刺激学习作为一种副作用而出现（如果我想要某些事物，我们便有可能尝试着去学习如何获得它）。

我们可以再一次使用变体老鼠去证实多巴胺的“想要”角色。基于不能释放多巴胺的老鼠，它们缺少朝奖励前进的动力。这便意味着这些老鼠虽然喜欢甜味的水，知道甜味水是来自饮水管的右边，但是它们却缺少动力走过去喝水。相反地，拥有比普通老鼠更多多巴胺的变体老鼠拥有更多动力去获取奖励—-不管是基于它们接近奖励的速度还是它们为了获取奖励所付出的努力。是否还记得那些脑子里带有电极，并且会为了获得更多刺激而牺牲一切的老鼠？我们也能够根据“想要”刺激进行解释（而不是“喜欢”刺激）。就像带有强迫性神经官能症（OCD）的人会反复洗手一样，尽管它们并不能从该行动中获得任何乐趣（实际上这是一种被迫性行为）。

让我们着眼于人类，当着眼于帕金森患者时，我们会发现有许多研究显示，当使用药物去加强多巴胺释放时，“想要奖励”的感受便会增加并因此而引出一些强制性问题。就像这些别人都有强迫性购物与其它“疯狂”的行为。

此外，如果我们着眼于有关某个人在大脑的“愉快中枢”中插上电极刺激时，我们便会注意到它们想要执行各种活动的原文和动机在不断提高。但是我们却未能看到有关这些人变得更加高兴的报告。通过种种数值我们可以发现这是对于多巴胺自我刺激的想要回应而不是喜欢回应。尽管它同时也指出，如果你一开始感到沮丧，但是突然受到激励去做某些事，那么这会起到某种副作用而影响你的情绪。

关于上述所有研究的结果便是，比起乐趣或学习，多巴胺更倾向于动机或强迫症。所以当我听到播客的主持人说因为游戏能够释放玩家的多巴胺，所以它们是一种强迫性行为时，我想他们应该是对的。但是多巴胺并不能直接赋予游戏乐趣。

这对于游戏来说意味着什么？

当时我们很爱将“神经”这一词用于各种内容上。在学术界，这便引起了神经怀疑论者的出现，即要求看到更多证据。毫无疑问，这种“神经学”深受欢迎。实际上，甚至有调查显示人们倾向于相信基于神经系统科学模式而呈现的数据，认为它们比基于普通模式的数据更具有科学性。

所以知道所有的这些神经系统科学对于那些创造游戏的人来说意味着什么？从使用角度来看，这对于每日游戏设计的作用并不大。我在此呈现的神经系统科学都是纯理论的，而不是使用科学，是基于我们所知道的某些特定奖励的传达奖励的方法具有特别的刺激性和乐趣的角度（在不同范围内可能或不可能与多巴胺有关）。例如：

*不可预测的奖励（随机掉落的战利品）总是比那些可预测的奖励更具有刺激性。

*奖励应该具有意义，例如食物对于那些已经吃饱的人来说便没有多大刺激性，或者如果你使用的是缺少突出视觉效果的设置，那么全新且独特的刺激内容便能够更轻松地吸引你的注意。

*人们更喜欢即时奖励和反馈，并且很难受到延迟奖励和反馈的刺激。在年轻时期，这种对于即时满足的偏好最为强烈，但也会随着年龄的增长而继续保留着。

*学习去获取并想要某种特定的奖励的想法会因为怎样的行为反应创造了该奖励的即时反馈而增强。关于怎样的行为创造了奖励的不确定性通常都会引起试错式探索，如果出现更进一步的奖励，这种情况便会继续下去。

*如果人们察觉到自己正在朝着奖励前进，即使该过程是幻觉，他们也有可能受到刺激而获得奖励。

*同样的，人们更愿意报告他们努力去挽留自己所拥有的内容，而不是获取自己未曾拥有的。

*人们总是更倾向于大数目。因此在某种程度上它们更喜欢通过战胜每个怪物获取100个XP或需要1000个XP进行升级的系统。

*预测一种奖励能基于行为反应而替代其它奖励（如在游戏中获得点数与拥有乐趣和点数是相互联系，并因此成为了一种刺激性奖励）。

*人们不喜欢那些让人觉得是受控制的奖励。

*如果某些内容比其它奖励更加难以获得，那么精通，自我实现以及不费力的高性能等感受便是一种奖励。

同样地，我所谈及的神经系统科学研究并不是针对于如何创造奖励自己或乐趣，而是注重理解它对生理的影响。如果这是基于一种使用角度，它通常是关于使用药物或直接的大脑刺激去获得结果。

基于游戏从实践的角度来看，然后着眼于游戏设计方向的行为将比从神经系统科学中寻求答案更有价值。的确，即使你能够记录下与游戏相互动的每个玩家的准确多巴胺活动，这也不能创造出具有实质性差别的设计结果。不过也存在例外，即基于理论的神经病学方法可以在无意识的情况下检测出玩家是否想要玩游戏，在这个例子中你也可以无需担心神经病学原理而知道未来行为的结果。这一切都说明，如果你真的想要知道自己的游戏将对人类大脑产生怎样的影响，或者你正致力于一款严肃游戏并想要知道游戏是否能够完善大脑功能的话，那么神经系统科学便是非常有帮助的方法。

因为当下人们更倾向于接受“神经”组件具有科学性的理念，所以基于这种模式去谈论游戏将会是一种更加可行的市场营销策略。但是我们也必须谨慎行事。现在人们似乎认为多巴胺与乐趣相关。同样地他们可能并不在意游戏宣传的目的在于提高多巴胺回应。但是如果某天公众认知发生了改变，人们将会更加清楚多巴胺是关于想要和动机，而不是乐趣，那么这些信息将变得更加难以揣测。因此，信息会从“这款游戏是致力于呈现乐趣，所以你才会想要去尝试它”变成“这款游戏的设计目的是为了让你去进行体验，有可能你根本就不喜欢这么做”。此外，还有一些证据能够证明那些备受压力（生理或心理）或缺少刺激的人更容易受到多巴胺激励效果的影响（这具有进化意义，就好象你现在处在一个糟糕的境遇，你便会受到激励而走出困境并冒险去完善状况—-但是在现代生活中，这种倾向有时候却是有害的）。结果便是，如果你是为了推动玩家多释放多巴胺并将其与盈利维系在一起而设计游戏，你有可能会发现这种方法将有效作用于那些不能有效捍卫自己同时也不大会为游戏花钱的人身上。除了道德感外，这种方法并不能为你带来什么，这种围绕着“多巴胺设计”的游戏（游戏邦注：即依赖于不确定奖励系统且带有直接行为反馈系统的游戏）可能会引来政府的管制（就像日本便已经限制了手机游戏中的某些“赌博”组件）。

一个复杂的问题

在完成这篇文章前，我们需要注意大脑其实是一个复杂的主题。当舆论界提到神经系统科学时，它们通常指代的是大脑的“愉快中枢”或特定神经递质在做一些特定的事。但这并不是实际情况，而是尝试着阐述一个真实故事的副作用那个。在现实中，生理学通常都会遵循着多对一或多对多的模式。也就是说这通常都不是X引起Y的情况，而是X，Z，B或C引起Y，或X，Z，B或C中的任何一个引起Y，J，A，K或U的任何一个，这都是依情况而定。此外，因为神经递质并不是独立存在着，所以你通常都能看到有关一种神经递质中的改变会影响其它神经递质的例子。多巴胺便是一个有效例子，即它是其它神经递质—-去甲腺上腺素的先驱，所以在多巴胺包含于想要奖励的情感中时，其它神经地址也会创造出这种效果。也许多巴胺只能在特定情境下创造出想要情感，但是在其它时间它也具有不同的影响。

另外一个复杂的问题便是，大脑领域的激活（或一直）将创造一种神经递质，如多巴胺，而它的影响将完全区别于其它特定神经递质（这也是我为何在一开始说只会讨论神经递质的行动而不会讨论大脑领域本身的主要原因），此外，接合点经常会被各种不同的化学物质（它们可能是因为能够更有效地吸引某种神经递质）所激活，这意味着在缺少多巴胺的情况下其它化学物质将会与这些点捆绑在一起。还有一个复杂问题则是，多巴胺只会在做出重复性动作时被释放（游戏邦注：如玩《摇滚乐队》或敲打控制器上的按键），而这与奖励可能有关系也可能毫无关系。

总结

在本篇文章中，我也提到其它神经递质的名字（如阿片类和大麻类），但是我主要还是专注于多巴胺所扮演的角色及其对于“想要”奖励情感的影响。

还有许多神经递质能够对人们对于游戏的反应产生影响。就像血清素。同样的，许多游戏也不只是关于奖励。它们也包含了社交元素（催产素和加压素便专注于这一点），竞争，技能表现，负面情感和正面情感，惩罚等等元素。的确，游戏与人类的大脑具有密切的关系。而如果你对大脑这一复杂对象感兴趣，你就需要更深入地了解并学习。但你也必须清楚，当前的人类更倾向于了解与神经相关的主题，而不愿变成神经怀疑论者。

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Dopamine and games – Liking, learning, or wanting to play?

by Ben Lewis-Evans

A few weeks ago when listening to a gaming podcast, I heard the hosts describe a particular game as “giving them their shots of dopamine”  in terms of the pleasure they had experienced with the game, and their desire to keep on playing (dopamine being a neurotransmitter i.e. a chemical used in the brain). The comment was made off-hand but reflects a common view – that having dopamine released is related to pleasure and reward, and therefore is relevant to gameplay. But is this view correct?

Well, if we go back around 30+ years, the view that dopamine is the chemical related to pleasure and reward was being presented by researchers. One classic experiment that led to this view of dopamine being related to pleasure comes from even further back and involved rats that had electrodes in their brain stimulating brain areas that (it turns out later) can be responsible the production of dopamine [1]. These rats could press a lever to get this part of the brain activated. In response to this self-administered brain stimulation the rats would push this lever at the expense of basically anything else. For example, they would rather press the lever than eat, be social, sleep, and so on. This, and other later evidence, led to this area of the brain being labelled as the ‘pleasure centre’ and seemed pretty convincing.

So, the conclusion at the time is that dopamine was the most important chemical that made us enjoy rewards and at the same time could motivate us to seek them out [2]. As such, the idea that dopamine is a reward and pleasure chemical, spread and is now mentioned off hand by podcasters (a very scientific metric of cultural spread, I know).

Unfortunately (well, actually in the long run, fortunately) the brain is not that simple. Science has moved on and things have changed. Indeed, a leading researcher in the area has, jokingly, suggested that that the best answer to the question “what does dopamine do?” is “confuse neuroscientists” [3].

That answer, while amusing (I laughed at least), doesn’t really help those working in games to understand what their games may or may not be doing to the brains of those playing them. As such, the aim of this blog is for me to as clearly as possible explain what Science currently says about the role of dopamine and rewards. More than that though, I will also try and provide some comment in terms of what all this neurotransmitter stuff actually means for people who make games.

Please note, in the following blog I will be limiting myself to talking about what is known about the effect of dopamine (the neurotransmitter) itself and not discussing what is known about the brain areas that are related to its production or suppression. I have also limited myself to only discussing the most relevant and interesting (in my opinion) examples and experiments as this is not the place for a full academic review of the subject (If that is what you want, check out the academic reviews listed in the reference section at the end of this blog [4-8]).

Liking, learning, or wanting rewards in gameplay

One useful way to approach the question of dopamine, and what it does, is to break down people’s reaction to rewards in terms of liking, learning, or wanting. Which is to say, that when it comes to how you react to a reward (such as achieving something in a game) then whether you like the reward (i.e. is it fun), have learned the appropriate way to get the reward (i.e. can you actually play the game), and if you want to work to get the reward (i.e. is it motivating to play), can be completely different, and independent, things.

Liking to play

It seems to make sense that if you do something for a reward then you must like that reward. This is indeed part of the reasoning that led early researchers looking at dopamine to assume that dopamine was to do with pleasure (‘liking’) [2]. Basically, they thought, why else would the rats have pushed that lever for so long if they weren’t enjoying themselves?

The idea that the self-stimulating rats were enjoying themselves may have been an understandable assumption. However, it turns out that while rewards are often liked they do not have to be liked in order to be effective in changing behaviour and, furthermore, that dopamine itself does not appear to be directly involved in ‘liking’ and pleasure.

Specifically, as research has moved on, it has become clear that animals (usually mice and rats) that have had their ability to produce dopamine stopped or restricted (either via drugs, surgery, or genetic alteration) can still be seen to demonstrate that they ‘enjoy’ and ‘like’ things. One demonstration of this would be that mice that have been genetically altered to not produce dopamine (a type of mutant “knock out” mouse, or an X-Mouse if you prefer) still show a preference for sugary water and other foods [9]. In that, these mice like and seem to show signs of enjoying the taste of sugary water and when given the choice will pick to drink it over plain, non-sugary, water. Furthermore, you can also genetically engineer mutant mice to have excess dopamine and these animals do not show any additional/enhanced signs of ‘liking’ different foods despite all the dopamine floating around in their brains [10].

So, that is mice but what about humans? Well, researchers aren’t really allowed to make mutant humans and it is not easy to get permission to give drugs or do brain surgery on people. But, we can look at patients with Parkinson’s disease, which is characterised by problems with dopamine production. These patients, much like the rats and mice, also do not appear to show any decreases in the liking of rewards, such as sweet tastes [11].

Given the above findings, and many others (e.g. see the reviews of [4-8]), it became hard for researchers to continue with the idea that dopamine is a pleasure or ‘liking’ chemical. In fact, by 1990, Roy Wise, a leading researcher and initial proponent of the idea that dopamine is related to pleasure stated:

“I no longer believe that the amount of pleasure felt is proportional to the amount of dopamine ?oating around in the brain” ([12] – p. 35).

Indeed, rather than dopamine it seems that other neurotransmitters, such as opioids (Endorphins! Remember when they were trendy to talk about?) and cannabinoids are actually more often involved in ‘liking’ a reward [4, 10, 13-15]). Although, it should be noted at this point that opioid release in the brain can, indirectly, also lead to reactions in the dopamine system, which again could explain the early confusion over the role of dopamine. However, as mentioned above, mice that are genetically unable to produce dopamine still do like things!

So, that pleasurable feeling you get when playing a game? Dopamine is probably not the cause. In the same fashion, if someone tells you their game is designed to maximise dopamine delivery then this does not necessarily mean their game will be fun or enjoyable to play.

Learning to play

If dopamine isn’t related to pleasure, then what does it do? Well, another hypothesis, which became popular in the 1990’s, is that dopamine helps animals learn how and where to get rewards (a very useful thing to remember in games but also in life in general). This hypothesis arose when scientists started noticing that dopamine activity appeared to increase before a reward was delivered and therefore could be helping animals predict the arrival of a future reward [6-8]. That is to say that dopamine was produced when an animal saw a stimulus (such as a light coming on) that had been previously linked to getting the reward and, therefore, the dopamine release was predictive of the reward coming and not a reaction to the reward itself (as it would be if it was just about ‘liking’ that reward or getting pleasure from it). There also seems to be an increase in the activity in the dopamine system when a reward is unpredictable (like a random loot drop in a game). That dopamine activity increased most when an animal was expecting or learning about an unpredictable reward appears to make sense if dopamine is about learning. After all, if a reward appears to be unpredictable then you should pay more attention/try and learn about what signals the reward so you can work out how to better obtain that reward in the future [16].

Again, this evidence for dopamine’s role in learning looked pretty good [7-8]. However, once again mutant mice have shaken up this idea. In a quite clever study in this area, scientists at the University of Washington showed that not only do mice that cannot produce dopamine still ‘like’ rewards but that they were also capable of learning where a reward was [17]. Specifically, these mutant knock-out mice could still learn that a reward (food) was in the left hand side of a T shaped maze, although they did so only after being given caffeine. The addition of caffeine to the mice is unrelated to dopamine production but was needed because without this mice that cannot produce dopamine don’t do much of anything. As you can see for yourself in this video with a normal and a dopamine deficient mouse the mutant mouse tends to just sit there. In fact, these mutant mice do so little that they will die from not eating and drinking enough unless given regular shots of a drug that effectively restores their dopamine function for a day or so [3].

In addition to the above experiment, it also appears that mice that have more dopamine than normal do not demonstrate any advantages when it comes to learning [3]. However, as mentioned, the fact that dopamine deficient mutant mice will essentially starve to death means that dopamine must do something. But if dopamine isn’t for pleasure from rewards, and isn’t for learning about rewards (although argument here still exists), then what does dopamine do?

Wanting (desiring, needing) to play

It turns out, as far as where science is currently at (and remember science does, and should, change as new evidence is found), that it seems that dopamine is most clearly related to wanting a reward [4-6, 15, 17]. This is not wanting as it would perhaps commonly be used in terms of a subjective feeling or cognitive statement like “Oh, I want to finish Saints Row IV tonight” but rather as a drive, a desire, or a motivation to get a reward. So, this is not about a feeling of ‘liking’ and pleasure, instead what we are talking about is a feeling of a need or drive to do something. Subjectively this may be like when you just have to take one more turn in Civilization (or start playing and then 5 hours later realise you are still going) or when you have just get a few more loot drops in Diablo before you stop for the night. Indeed in the literature, when discussing the results of experiments on mice, some researchers suggest that dopamine creates a ‘magnetic’ attraction or compulsion towards obtaining a reward [3, 6]. Indeed, it could be argued that the evidence for dopamine being involved in ‘learning’ is in fact just a sign of ‘wanting’ being directed towards an uncertain reward, which then motivates learning to occur as a side effect (i.e. if I want something, I am likely to try and learn how to get it).

Again, here, we can look at mutant mice to confirm the role of dopamine in ‘wanting’. In mice that cannot produce dopamine, their motivation to move towards and work for rewards (which, remember, they do like and have learnt how to get) is deficient [3, 17]. This means that these mice do like sugary water, and they have learnt that the sugary water comes from the drinking tube on the right; however, they just aren’t motivated to walk over there and drink it [3]. Conversely, mutant mice that have more dopamine than is normal have been shown to be more motivated to gain rewards, both in terms of how fast they approach rewards and how much effort they will expend to get the reward [3, 10]. Also remember those rats with electrodes in their brains working away at the expense of everything else just to get more stimulation? Well that can also be explained in terms of ‘wanting’ the simulation rather than ‘liking’ it [1, 2]. Kind of like how someone with OCD will wash their hands over and over and over again, even though they often get no pleasure from this act (and in fact it can be quite distressing).

Looking at humans, if we examine patients with Parkinson’s disease then there are also studies that show that some of these patients demonstrate increased ‘reward wanting’ and have compulsion problems when given a drug that enhances dopamine production. For example, such patients have been reported to go on obsessive shopping sprees and demonstrate other ‘manic’ type behaviour [18].

Furthermore, if we go back and look at reports of people who, like the previously mentioned rats [1], had direct (self) electrical stimulation of their so called ‘pleasure centres’ in their brain (usually for questionable medical reasons), then we see subjective reports of increased sexual desire or motivation to perform various activities (or just to press the button to self-stimulate, which they would do thousands of times). However, we do not actually see clear reports from these people of increased pleasure, sexual or otherwise (these accounts are mostly from the 70’s & 80’s where this kind of thing was going on, and are summarised in [2] if you are interested). In one highly ethically questionable example, the researchers actually hired a female prostitute at the request (although, one could easily question if this was a true, ethically acceptable, request) of an electrically self-stimulating man who was being ‘treated’, in part, for homosexuality, along with depression, drug abuse, and epilepsy [19]. So, in these human accounts we see suggestions of what looks like a wanting response to self-stimulation of dopamine related brain areas but not necessarily a liking response (i.e. the subjects expressed increased desire but not necessarily increased pleasure). Although, it should be pointed out that if you were depressed, and then suddenly started feeling motivated to do things again that this may, as a side effect, increase your mood [2].

The upshot of all of the research mentioned above is that it appears that dopamine is not directly about pleasure (or learning) but rather it is about motivation or, if you want to be more sinister, compulsion. So, when those podcasters I was listening to said that a game was compulsive because it was giving them their dopamine shot, they may have been right. However, dopamine was not directly responsible for also making the game they were talking about fun (please note, I am not so serious that I expect videogame podcasters to be exact about this kind of thing, rather I am just using them as a convenient example).

What does this mean for games?

It is very popular at the moment to attach the term ‘neuro’ to almost anything. In academia this has led to a, justified in my opinion, neuroskeptic movement that is calling for, well, more evidence. However, there is no doubt that this ‘neurofication’ is popular with people. In fact, there is even research [20] showing that, at the moment, people seem to have a bias towards believing that data that is presented to them in a neuroscience-like fashion (i.e. via an image of a brain scan) is more scientifically valid than the same data presented to them in a more mundane fashion (i.e. via a bar graph).

So, what does knowing all this neuroscience mean for those who are making games? Well, from a strictly pragmatic and applied perspective it could be argued it means very little for every day game design. The neuroscience I have presented here is mostly pure, not applied, science and comes from the perspective that we already know that certain rewards and ways of delivering reward are particularly motivating and pleasurable (and may or may not have anything to do with dopamine to different extents). For example:

- Rewards that are unpredictable (loot drops) are generally more motivating than rewards that are predictable (100 xp per monster) [21-23].

- Rewards should be meaningful, e.g. food is not particularly motivating for most people if you are already full, or if you are in a relatively visually sparse setting then new, unusual, stimuli will attract your attention more readily [16].

- People tend to have a preference for immediate rewards and feedback and are not so motivated by delayed rewards and feedback. This preference for immediate gratification is strongest when young, but persists throughout life [24-26].

- Learning to get and want a certain reward is enhanced by immediate feedback about what behavioural response produced that reward. Uncertainty about what behaviour produced the reward will often lead to trial-and-error type exploration, which will be more likely to continue if further rewards arrive [23, 27, 28].

- If people perceive they are progressing towards a reward, even if that progress is artificial/illusionary, they are more likely to be motivated to obtain the reward (just one more turn…) [29].

- Similarly, people tend to report that they will work harder to keep what they have rather than to gain something they don’t yet possess [30].

- People have somewhat of a bias towards large numbers. Therefore to some extent will prefer, and be more motivated by, a system where they earn 100 xp per monster and need 1000 xp to level up over a system where they earn 10 xp from a monster and need 100 xp to level up [29, 31].

- A predictor for a reward can serve/become a replacement for that reward in terms of behavioural response (e.g. getting points in a game becomes associated with having fun and points can therefore become a motivating reward in themselves) [21-23, 29, 32, 33].

- People tend to dislike rewards that are delivered in a way that is perceived to be controlling [22, 34-36].

- Feelings of mastery, self-achievement, and effortless high performance appear to be quite rewarding, if somewhat more difficult to achieve than other types of reward [35-37].

As such, the neuroscience research I have discussed isn’t, primarily, aimed at working out how to make a reward motivating or pleasant but rather at understanding why it is so at a physiological level. Or if it does take an applied view, it is usually about using drugs or direct brain stimulation to get results.

As such, from a practical perspective in games, then looking at behaviour (such as the masses of data being collected all the time on player behaviour by metrics or even your own small scale playtests) for game design directions is likely to be more valuable than looking to neuroscience for answers. Indeed, it is likely that even if you could record the exact dopamine activity of every player that interacted with your game that it would not really produce a substantially different design outcome than just looking at what they do (i.e. their behaviour). One exception could be that a theoretical neurological approach may be able to detect if a player was ‘wanting’ to play your game without consciously realising it (something that may indeed be possible) but even in this case you could still see the same outcome in their future behaviour without having to worry about the (complicated and costly) neurology of it. All this said, if you are interested in knowing what your games may be doing to peoples brains, or perhaps you are working in serious games and want to see if games can improve (or worsen) brain function. Then, here, neuroscience can be valuable. But please, be neuroskeptical!

One possible application of the research I have outlined here is, I guess, that because at the moment people seem biased towards accepting explanations with a ‘neuro’ component as being more scientific [20], then you could argue that talking about games in this fashion could be a viable marketing strategy. Be careful though. At the moment people appear to think dopamine is related to pleasure. As such, they may not mind games being publicised or talked about as being designed to maximise a dopamine response. However, if the public perception changes and it becomes even clearer that dopamine is about wanting and motivation, not pleasure, then such messages become more sinister. In that, the message changes from “this game is designed to be fun, so you will want to play it” to “this game is designed to make you want to play it, even if, perhaps, you don’t like or enjoy doing so”. Furthermore, there is some evidence that people who are already stressed (physically and/or mentally) or lacking in stimulation are more vulnerable to the motivational effects of dopamine (this makes evolutionary sense, as if you are in a bad position at the moment you should be motivated to go out and take risks to try and improve things – but in modern life this tendency can sometimes be harmful) [16]. The upshot of this is that if you design your game to really push dopamine buttons and tie that into some kind of monetization (or even if you are just asking people to give you their time), then you may have to take the risk that those aspects will be working best on those who are less able to defend themselves and may also be the least able to pay (and you can’t even necessarily suggest that at least you are giving them a fun time because liking, while often correlated with, is not needed for wanting). Aside from any moral feelings this may or may not produce for you, such ‘dopamine designed’ games (which would most likely be games that rely on uncertain reward systems with good direct feedback systems on behaviour) may attract the eye of governments and lead to regulation (as, it could be argued, it already has in Japan with the restriction of certain ‘gambling’ components in mobile games).

A complicated matter

Before I finish up, it should be noted that the brain is a complex subject matter. When neuroscience is talked about in the media there are often references to brain areas being ‘pleasure centres’ or certain neurotransmitters doing very specific things. But that is not the reality but rather a side effect of trying to tell a clear story. In reality physiology often follows a many-to-one or many-to-many pattern. Which is to say it is not usually a case that X causes Y, but rather that X, Z, B, and/or C can, if circumstances are right, cause Y or even that any of X, Z, B, and/or C can cause any of Y, J, A, K, and/or U, depending on the situation. Furthermore, since neurotransmitters don’t exist in isolation you often have instances where changes in one neurotransmitter will affect one or more other neurotransmitters. Dopamine is good example of this as dopamine is a precursor for another neurotransmitter, norepinephrine. So while dopamine may be involved in wanting a reward other neurotransmitters many also produce this effect. Or maybe dopamine only produces wanting when certain other situations are met and has different effects at other times.

Another complication is that it may be possible that the activation (or suppression) of brain areas that produce a neurotransmitter, such as dopamine, can have effects completely separate from the specific neurotransmitter that you are examining (which is why, at the start of this blog I said I was limiting myself to just discussing the action of the neurotransmitter and not of the brain regions themselves). Furthermore, binding sites (where neurotransmitters fit and work) can often be activated by multiple different chemicals (they just may be more strongly attracted to one neurotransmitter), meaning that in the absence of dopamine perhaps another chemical binds a these sites. Another complication would be that dopamine appears to be simply released during repetitive motor movements (such as where you play Rock Band or are just tapping away on buttons on a controller), which may or may not have anything to do with rewards [38].

Conclusion

In this blog, I have mentioned a few other neurotransmitters by name (e.g. opioids and cannabinoids) but I have focused purposefully on the role of dopamine and its role in ‘wanting’ rewards (it is likely that dopamine does more than this but ‘wanting’ seems to be its main role in terms of rewards). As such, I hope that this blog has been an interesting read and that maybe you have learned one or two new things.

However, there are many more neurotransmitters could play a role in how people react to games. Serotonin, for example, is likely to be involved [14]. Also, many games are more than purely about reward. They also often involve social aspects (oxytocin and vasopressin are the neurotransmitters currently getting the most attention here), competition, skilled performance, negative, as well as positive, emotions, punishments, and many other factors. Indeed it seems that games are thankfully, much like the human brain, a complex subject matter. So, if this kind of subject interests you then read and learn about it (check out the references below, the majority of which are open access and not locked behind paywalls). But be aware of the current human positive bias towards neuro-related subjects and instead try to be neuroskeptical.(source:gamasutra)