Cognitive Science: An Introduction/Perception's Role in Cognition

We can give a loose definition of perception as converting energy, or some other part of an agent's environment, into representations in the agent, or to help the agent navigate the world.

Perception can be incredibly complex, as when we one finds the right key in one's purse in the dark, just by touch, but can be quite simple too. We can even look at immune systems as having a very simple form of perception. T cells can recognize invaders with a sensor on the surface of the cell, called a T-receptor. If the T-receptor binds to a cell, it triggers a signal to kill it.

A erythrocyte, thrombocyte, and T cell (on right, in blue). Even T cells can do a limited form of perception.

Organisms harness energy from the environment to perform a multitude of biological, chemical and mechanical operations. Most organisms, for example, capitalize on the work done by plants to convert energy from the sun into chemical energy (glucose). The energy contained in glucose bonds is then used by organisms to drive much of the work within their own bodies or cellular structures. Sunlight, or electromagnetic energy, however, is not the only kind of energy that can be used to perform work, and metabolism is not the only kind of work that can be completed. Instead, humans, animals and other information processing systems (e.g., intelligent machines) are able to convert a broad spectrum of environmental energy and information into electrical energy, which is used to drive the astonishing cognitive processes each of us is familiar with. Although we still do not fully understand how neural processes in our (and other animal) brains result in these cognitive experiences, we have learned much from psychological and neuroscientific studies about how energy in the environment can be converted into electrical energy, as well as what kinds of cognitive experiences we believe are possible in other animals. The study of artificial agents capable of sensing their environments and using this information to drive action is another powerful paradigm that has proven fruitful. This chapter will explore human and non-human sensation—the process of recognizing information and receiving energy from the environment through our sensory receptors—and perception—our mental interpretations of these sensations.

In humans, the somatosensory system is responsible for sensing the chemical, electro-magnetic, mechanical and thermal information in the environment that ultimately leads to our visual, auditory, gustatory, olfactory, haptic and proprioceptive perceptual experiences. Highly specific sensory receptors across our bodies are able to interact with specific kinds of information in the environment. Ultimately, if a sensory receptor interacts with enough of the right kind of information, this information will be converted, or transduced into an electric signal. Regardless of whether a photon of the appropriate energy falls on a photoreceptor in your retina, or a pressure wave of appropriate decibel and frequency range vibrates the mechanoreceptors in your inner ear, successful stimulation or sensation results when this environmental information is transduced into an electric signal. By transforming the energy and information in our environment into an electrical currency our neurons can use to communicate, our sensory system sets the stage for our brains to imbue sensation with the individual conscious experiences we each perceive after sensing our environment in different ways.

A quick survey of various sensory aptitudes throughout the animal kingdom promptly reveals a fundamental characteristic of sensory systems: they are limited. Sensation and perception allow organisms and machines to absorb and interpret only some of the information in the immediate environment. In the same way that you are unable to perceive the high-pitched whistle that your dog might take as a sign of dinner, other animals are able to see only a fraction of the colours humans perceive. Despite these sensory differences, we are not the only animals capable of cognitive processing and thought. Our own sensory abilities, as we will see, are also much more limited than our conscious experiences may lead us to believe. Nevertheless, our brains are able to use a limited subset of the information available in the environment to construct a cognitive narrative that allows us to think, reason and interact. Understanding the nature of this information as well as the differences in other sensory-perceptual systems (biological or otherwise) and the sort of cognitive processes they sustain, can help to uncover much about the basic building blocks of cognition.

There are some feelings that are hard to categorize either as sensations or emotions, such as familiarity, certainty, or novelty.