In this section a short overview of perception and cognition in nature is presented as a motivation and inspiration for the further work on context acquisition. These processes in nature are extremely complex and there is no attempt in this research to recreate or simulate them. However looking at perception, cognition and the way sensory inputs are processed in nature provides many interesting ideas that can influence the design and development of Ubiquitous Computing systems.
Acting and reacting with respect to the current situation is a basic property of most intelligent systems. Looking at flora and fauna it is a major advantage in the struggle for survival to have the ability of being adaptive. The capability to adapt to new circumstance and situations is a vital quality for virtually all living organisms and a major advantage in the struggle for survival [Darwin,59].
Considering the evolution of life, adaptation over generations is a key success factor; this can be compared to anticipating the context of use at design time. This also relates to development processes of context-aware systems, which often occurs in generations, e.g. project TEA [TEA,98] and project Smart-Its [SMART,02]. The basic concept is to use experience from one generation for an improved design of the next generation, optimising and specialising the system. This approach is widely used [Want,02].
The use of context at run-time is comparable to the adaptation of life-forms to short term or sudden changes in their environment, such as day and night, danger, drought, and temperature changes. A prerequisite to these short-term adaptations is the availability of perception and cognition mechanisms.
Having perception and cognitive functions are the foundation of intelligent behaviour of creatures and these concepts are strongly related. The following basics of sensing, perception, and cognition are described to provide some insight in these processes. In this work it is not anticipated to model these processes for building systems, but nevertheless they are taken as motivation and as a source of inspiration for the design of the sensory part of context-aware systems.
The research into the senses that are the basis for human perception has been a challenge for a long time. A description can already be found in the works of Aristotle [Aristotle,00]. In this theory, based on the knowledge of elements at that time, it is argued that the five senses are enough to perceive everything that can be perceived. The senses named are: vision, hearing, smell, taste, and touch. This list of human senses was extended in the 19th and 20th century by: the perception of position and constellation of parts of the body, the vestibular system, and perception of pain and temperature.
Research in zoology showed that some animals have developed further senses. There are fishes and amphibians that can perceive electric fields as shown in [Scheich,86]. In [Able,90] evidence suggests that some birds have the ability to sense the direction of the magnetic field of the earth. The quality of the sense and the ability for perception varies between creatures to a great extent. In nature it can be observed that the perception capabilities of different species are closely related to their way of life. It can be observed that the requirements imposed by the environment influence the senses and perception developed by a life form.
The following senses have been a point of inspiration when searching for sensing and perception technologies2. • Vision • Hearing • Smell • Taste • Touch • Temperature
• Gravity and acceleration (similar to the vestibular system) • Position and constellation of (body) parts
• General magnetic fields and in particular the magnetic field of the earth • Electric fields
Senses in nature cannot be directly compared to sensors in a technical world. Senses comprise the whole process from the reception of the stimulus, translation from stimulus to signal, signal transport and the processing on several levels. In particular the processing of neural signals is very complex and not fully understood. The basic assumption is that the information sensed from the environment is translated into patterns. These patterns are than associated in further process steps with meaningful concepts. This leads to the assumption that perception is not possible without memory, as claimed in [Neisser,76] and in [Goldstein,97, p. XXI].
To understand or at least interpret information that is sensed from the environment knowledge or experience is required. Creatures learn during their development how to assign meaningful and abstract situations to complex stimuli received by the sensory system. This is based on the presupposition that similar situations are characterised by similar stimuli, as discussed in detail later. Comprehension of a situation or understanding of the implications given by a situation is a further step, which is to a great extent based on the recall of experience.
2 The perception of pain is not further investigated because they are very specific to creatures. Similarly sense that are more complex such as perception of emotions are left aside, because they are not directly related to a sensory input as they rely on multiple senses mentioned above.