Better to plow through and write something that needs to be rewritten a few times than spend forever wondering how you plan to write it. In that vein, I've just ploughed through on the perception discussion. It's very rough, but at least the log-jam appears to have partially broken. I decided to start, as the original thesis did, with a discussion of the concept of perceptual fields. The section on neurology probably seems a little out of place at the moment, discussing (later) the various aspects of cognition where the neurological underpinning shows up is the reason for its presence.

I will not draw any strong line between perception and cognition here, as their operation is similar, and arguments for drawing a sharp distinction are rather poor. To understand perception (and cognition) as it applies to design, we will once again apply an expansive definition.

The goal of perception is to allow us to cope with our environment.
It is somewhat problematic to state that there is a “goal” to perception, as that implies that something has established that goal at some point. However, for now, given the focus of our studies, it is reasonable to imagine that our goal in perceiving and thinking is to allow us to better survive and thrive within our environment. Similarly, we might suggest that the purpose of our eyes is to see, that the purpose of our ears is to hear, and the purpose of our nose is to smell.

Perception is a complex, poorly-understood process, so any presentation of it for use in a practical context will necessarily gloss over important features. We will, however, attempt to explore the basic features of perception in sufficient detail to allow us to make judgements about how to affect the processes involved.

The first concept we need to treat is that of “perceptual fields”. A perceptual field can be thought of as “that which is presented to the perceiving individual”. The easiest form of perceptual field to imagine is the simple combination of all current input for a given sense. For instance, that which can be seen with they eyes, or that which can be heard with the ears. The perceptual field here is quite simple in its structure, and can be understood as something like what a camera or microphone might pick up when exposed to the same environment.

However, a visual or auditory field is seldom perceived without input from other senses. A door appearing to open in a movie is perceived quite differently if creepy music and a loud squeak accompany it. Our minds combine the input from multiple senses into a combined sensory experience. This combination of effects is not confined to the traditional 5 senses. Our internal bodily “senses”, such as pain, hunger, muscular tension and the like also feed into our perception of our environment. We perceive the duration of a wait in line as being much longer if our bladder is constantly prompting us that it is full. Our immediate perceptual field thus includes that which we may consider immediate “needs” and bodily feedback regarding, for instance, our current posture and respiration rate.

This is not to say that all perceiving individuals suffer from synesthesia. Rather, most individuals correctly perceive the source of a given stimuli, but their perceptual systems allow them to appreciate phenomena which affect multiple senses as being coherent. We associate seeing a pair of hands clapping with the sound made, the same perceptual system operates on both sets of stimuli.

Of course, to recognize “clapping” as a phenomena, we must have another source of information available to our perceptual system, namely some knowledge of our history of perceptions, or the conclusions we have reached about those perceptions. We are fairly good at perceiving temporal patterns among percepts. We hold patterns in mind which may be satisfied and if they are satisfied those patterns themselves become part of our perception.1 Beyond the immediate pattern recognition, our mind retains a model of its expected environment, and those expectations are available to the perceptual system to determine whether new stimuli match or do not match expectations.

To summarize, our perceptual field is the sum of all of our current and past sensory input and the traces of our past perceptions. Together they form the raw material against which our perceptual systems “run” to attempt to provide us with the information we need to better cope with our environment.


We'll take a brief excursion here into a sketch of how human physiology appears to be constructed with regard to perception and cognition.

Human minds are, at their most fundamental, pattern matching machines. When presented with a perceptual field, we process the field using a huge number of neurons, which are presented with the information in the field and which act to pick out those features of the field which match the pattern the neuron (or set of neurons) encodes. When a neuron is stimulated, it in turn may stimulate other neurons. Those neurons in turn may be stimulated if the pattern of incoming neurons matches the pattern they embody.

Neurons have the potential to become “partially excited”, and may have temporal qualities, such as resisting further stimulation until a given time has elapsed, then being available for stimulation for only a short period before reverting to a ground state. From our perspective, these are “expectations” which may or may not be fulfilled, such as the expectation of the continuation of the beat in a song, or the expectation involved in “waiting for the other shoe to drop”.

In any given “concept” there may be hundreds to millions of neurons involved, with incredibly complex chains of patterns and enormously complex and potentially redundant operations involved in identifying the concept. We learn very early to identify, for instance, objects moving in our visual field, and the faces of human beings and their expressions. We learn to detect the effects of light on surfaces and become so good at picking out “objects” in our environment that these operations happen far below our level of conscious activity when we are adults. For an adult, seeing an uninterpreted visual field, without any interpretive operations is extremely difficult. We “see”, instead objects arranged in space.

What does the biological view of perception provide us? For instance, do we perceive the effect of a partially excited neuron? Is this “expectation”? Do we feel the potential draining away from a neuron that was waiting for a stimuli that never arrived? Is this “disappointment”? Does the “fuzzy” nature of our pattern matching affect how we understand our environment? Will a sufficiently strong set of stimuli X and Y for a neuron that normally mediates X, Y and Z overwhelm the neuron and cause it to fire as though all stimuli were present.

I will end this little excursion with this caveat; while understanding the biological (neurological) basis of cognition may be helpful in pointing out general features of cognition that we can exploit to improve our designs, we are primarily interested in manipulating much higher-level cognitive operations than fall directly out of such knowledge.