Taking the emphasis on the player further, Dan Cook (pictured left) explored some ideas about a psychology of game design in his 2007 article The Chemistry of Game Design, within which he denies that games are statistical systems:

Many of the attempts to define games have focused on the mechanistic elements of the game, such as the primitive actions that the system allows the player to perform or the tokens that the player manipulates. The approach has been to treat games as self contained logical system. Mechanics and aesthetics are certainly important pieces of any model of game design, but in the end, such analysis provides little insight into what makes a game enjoyable. You end up with a set of fragmented pieces that tell you almost nothing about the meaningful interactions between the game as a simulation and the player as an active and evolving participant. Games are not mathematical systems. They are systems that always have a human being, full of desires, excitement and immense cleverness, sitting smack dab in the center. To accurately describe games, we need a working psychological model of the player.

Although this may seem to be arguing against the systems aesthetic, there is no denial here that games are systems. What Cook denies is that games can be understood solely as mathematical systems, instead advocating an examination of the psychology of players since the system means nothing without the player – something few would argue against. He continues:

Our player model is simple: The player is entity that is driven, consciously or subconsciously, to learn new skills high in perceived value. They gain pleasure from successfully acquiring skills.

Koster has expressed his pleasure with Cook's approach here, and small wonder – it has the learning aesthetic right at its heart. Indeed, with their shared interest in both systems and learning, Koster and Cook are aesthetically very close to one another – Cook even directly references A Theory of Fun for Game Design and encourages people to read it, and makes Koster-esque assertions such as:

The sensation that gamers term 'fun' is derived from the act of mastering knowledge, skills and tools. When you learn something new, when you understand it so fully you can use that knowledge to manipulate your environment for the better, you experience joy.

Note that Cook does not claim that players enjoy exercising their mastery but from the act of mastering. Again, the learning aesthetic is being placed ahead of the mastery aesthetic – players "gain pleasure from successfully acquiring skills", not from successfully exercising those skills. Cook, whose entire article is written with an evident adoration of positivistic science, draws against neuroscience to support his claims – but goes slightly awry in doing so. He cites neuroscientist Edward Vessel's remarks concerning what has been called the "click" of comprehension, and comments:

Upon the click of comprehension, a natural opiate called endomorphin, a messaging chemical in the brain similar in structure to morphine, is released. As humans, we are wired to crave new information constantly. In some sense, what you and I term curiosity can be interpreted as our brain looking for its next fix of deliciously fascinating information.

This is a correct interpretation of Vessel's work, but it misses out a great deal of what is interesting about it. Vessel, along with Irving Biederman and Xiaomin Yue, have conducted considerable research into the function of endormorphin and the receptors it binds to, and do say many things that support Koster and Cook's position. For instance, Biederman and Vessel allege:

We should add that the time course of cognitive pleasure may be somewhat protracted for children. A child may wish to hear the same story read to her over and over again (much to the chagrin of an adult reader), even to the point where sections of the story are memorized verbatim. However, when the youngster is questioned about the story—for example, why a particular character acted in a certain way—the child often reveals a lack of comprehension. It's only after a child fully understands the point of the story that she tires of hearing it again. This may be analogous to an adult's experience of mastering challenging subject matter. The payoff is in the click of comprehension, however difficult the path to that point.

However, while Biederman and Vessel's work does involve demonstrating learning outcomes associated with "novel" and "richly interpretable" experiences, this learning aspect is tangential to the core of their work, which is concerned with the neurobiology of perceptual pleasure. These kinds of experiences are rewarding because they are richly interpretable, not because learning occurs (although, as a later paper with Yue demonstrates, the endomorphin system triggers the dopamine system, which as Koster correctly observed is involved with learning). Curiosity is not a motivation towards learning, as Cook implies, but an inherently enjoyable experience. The learning, as mentioned previously, is always going on in the background, but it would be incorrect to single out the learning as the sole purpose of this neural activity. Biederman and Vessel have demonstrated, for instance, that people "enjoy searching for target images... as long as they can maintain a reasonably high level of accuracy" – this is an activity that involves endomorphin, but the reward comes from recognising the target image, not from any learning that might result. In so much as enjoyment here is related to actual performance, this could be an example of the aforementioned mastery aesthetic.

Cook's general approach to games and play does gain some support from Biederman and Vessel, however:

It may also be the case that some childhood behavior does not engage the reward system considered here. Video games are replete with repetitive perceptual inputs that seem to be endlessly amusing to young people. We suspect that children can tolerate the repetition because they are rewarded with ever-increasing scores until the game is mastered. It would be rare for someone to seek the repetitive stimulus of a game without having access to the controller! In general, many repetitive activities expressed during childhood may serve to build motor skills or improve performance, rather than increase knowledge.

Since Cook's player model focuses on the acquisition of skills, the contrast here between building motor skills and improving performance versus increasing knowledge doesn't give him issues – although it is reasonable to suspect something is being lost here. Cook claims that "When you learn something new, when you understand it so fully you can use that knowledge to manipulate your environment for the better", which runs contra to Biederman and Vessel's comments about videogames, where they expressly deny that knowledge is the critical element. It may well be for many players, especially those that favour problem aesthetics of play. But seeking improved performance is not the same as seeking new skills, for all that the improvement may be explicable in terms of skill acquisition: the goal is mastery, not learning, and the fun can lie in the exercise of the mastery, not in the understanding of it.

Of course, Cook has a much better understanding of videogames than Biederman and Vessel do! They make a mistake, for instance, in believing that it is only children that tolerate the repetition in such games – as any World of Warcraft player will attest. Even allowing for this, there is room for improvement in Cook's understanding of the relationship between curiosity and play, and between mastery and skills. Cook is insistent that the pleasure from mastering a skill is experienced only once, stating: "After the moment of mastery, a biological feedback system kicks in that dampens the pleasure response to exercising those same pathways again. What was once exciting becomes boring." His 'moment of mastery' is intended to be Vessel's "click of comprehension", but this should not be applied to skills, only to knowledge. The "click" concerns successful interpretation of a situation, and has actually very little to do with the more general process of skill acquisition, which can be continuously rewarding. A musician never masters their instrument in such a way as to become bored of it – their pleasure in developing a masterful musical skill is felt in their exercise of that skill, something that is obscured in Cook's account. Similarly, a game player may never know that they have mastered a skill, but they may still enjoy exercising it.

Like Koster, Cook prioritises the learning aesthetic over the mastery aesthetic. But Cook also misses out on another aesthetic experience his account comes extremely close to recognising – what we could call the curiosity aesthetic. The research on endomorphin is not just about the "click of comprehension", it is about why we find some perceptual experiences pleasurable. Part of this is because novel, richly interpretable images can be enjoyed whether or not any learning takes place. Curiosity does play a role when a puzzle is solved – it is part of what motivates the individual to attempt a solution – but players can enjoy curiosity that doesn't lead to such blunt payoffs, and frequently do. Exploring an intriguing terrain is fun for some players not because being able to navigate in that world is a skill with high perceived value (although it will be for some players), but because the landscape itself is richly interpretable. This is another way of saying that curiosity itself is fun, even if it never leads to learning.

Next week: McGonigal and Suits