Human Factors in Engineering (Article #40, Written in April 2, 2006)

Experimentation: Natural sciences versus people’s behavior sciences

This article is intended to compare the kinds of controlled experiments that are applied by scientists in physical natural phenomena and those developed by scientists dealing with the behavior of people, or employing human participants in the experiments.

Although the physical sciences, such as all the branches in physics, chemistry, and engineering…, used controlled experimentations long time ago to develop the huge body of knowledge on the natural phenomena, it was the social and psychological sciences that tried to develop the appropriate and complex statistical modeling packages in order to study the more complex and more varied human behaviors.

It appears that the restricted and countable number of variables in studying the physical natural phenomena, and their relative lack of variability with time, did not encourage the physical scientists to contemplate sophisticated statistical models for their controlled experiments, or even to teaching the design of experiments in the engineering curriculum.

Before we expand on the variability of human behaviors, it might be more appropriate to analyze the most critical difference in the two sciences. Knowing that any concept is synonymous with the corresponding necessary set of operations, in order to be able to measure it scientifically in experiments, we can understand the big leap forward of the body of knowledge in natural sciences compared to the social and psychological sciences.

Whereas the physical scientists can define the concepts of force, moment, power and the like through the relationships of measurable variables based on length, time, and mass, the scientists investigating human behaviors have to surmount that hurdle (of accurate measurements) before seriously contemplating to measure human concepts.

Human behavior and the cognitive concepts of attitudes, mental abilities, and moods, problem solving mechanisms, perception, and the like cannot be measured scientifically until sets of operations are agreed on, for each one of these concepts, through the study of human activities or the things that people do while performing a valid task or a set of purposeful tasks.

For example, saying that color blindness is a deficiency that confuses colors will not cut it:

1. what is needed are a set of instances that could define this illness such as what exactly are the colors of the spectrum with mixtures of two primary colors can a protanope (color blind individual) match that are different from normal people

2.   Will the subject confuse a blue-green color with white or gray?

3. Will he confuse red, orange, yellow, yellow-green, and green when suitable brightness and saturations of these colors are used, and has reduced visibility in the red end of the spectrum?

Two decades ago, the air force in the USA contracted out groups of psychologists and human factors professionals to specifically establish a set of operations that could be submitted to potential airplane fighters in order to measure and evaluate their capabilities for the mental and perception workload needed for the job. This set of 12 operations measuring short term memory capacity, reaction times, computational abilities, attention span, and types of errors committed in each operation is the kind of hurdles that the study of human behavior have to surmount.

The operationism of a single human concept may be a life project for a group of scientists that require secure and continuing funding from concerned parties who have vested interests in thorough study of the concept.  It is obvious that a few fundamental and limited human concepts will enjoy deeper and more complete investigations than others.

May be because the physical scientists did not face the problems of establishing sets of operations that the method of controlled experimentations was not deemed essential enough to rigorously teach in high school programs, and ultimately failed to initiate the students to the experimental methods.  Until recently, when social sciences made significant in roads into the educational programs.

This lack of early initiation of students to experimental methodology might also be the main reason why rational thinking and the experimental mind is not that widespread throughout all societies, and are just confined to the privileged who could afford higher educations at select universities.

Physical scientists rely on equipments to objectively observe and measure, the more the equipments are precise the more accurate are the data.  The scientists of human behavior have to rely on people’s responses and observations.

For example, it has been proven that:

1. man is not a good observer of complex events; even when viewers are forewarned that they are to see a movie about a crime and that that are to answer questions about details later the accuracy of the observers are very low.

2. Man is unable to be an objective recorder of the events that transpire because he gets involved in the scene actions.

3. Man has a very narrow range of attention and barely can satisfactorily attend to a couple of stimuli. This observation deficiency is compounded by our sensory differences and illusions; for example, one in sixteen is color blind, many suffer from tone deafness, taste blindness and so on.

4. Man does not think of himself objectively but rather has convictions, feelings, and explanations based on very restricted experiences, hearsays, memories and he tends to generalize and develop a set of beliefs concerning the operation of the mind.

5. Man usually expects to see and then see what he wants to see and hardly deviates from his beliefs, and sometimes even when faced with facts.  For example, many scientists have overlooked obvious data because they clanged to their hypotheses and theories.

6. Man has to generate an abundance of reliable information and assimilate them before he could eliminate a few systematic biases that he acquired from previous generations and his personal experiences.  Consequently, experimenting with people is more complex and more difficult than the physical scientists or engineers have to cope with.

First, there are no design drawings for people’s mind and behavior as engineers are familiar with because the structure of human organisms is approximately delineated and the mechanisms are imperfectly understood.

Second, people vastly differ in anthropometric dimensions, cognitive abilities, sensory capabilities, motor abilities, personalities, and attitudes.  Thus, the challenge of variability is different from physics where phenomena behave in stable fashions, are countable, and can be controlled with minimal management.

Third, people change with time; they change in dimensions, abilities and skills as well as from moment to moment attributable to boredom, fatigue, lapse of attention, interactions among people and with the environment.  People deficiencies in senses, physical abilities and cognitive capabilities changes with time and thus, the techniques of selecting subjects have to account for the differences in age, gender, specific deficiencies, training, educational levels, communication skills, and incentives to participate in an experiment.

Fourth, the world is constantly changing and systems used by people are changing accordingly.  Thus, interfaces for designing jobs, operations and environment have to be revisited frequently to account for new behavior and trends.

Fifth, everyone feels that he is an expert about human behavior, on the basis of common sense acquired from life and specific experiences and we tend to generalize our feelings to all kinds of human behaviors but not so expert in the fundamentals of natural sciences such as physics or chemistry.

We think that we have convictions concerning the effects of sleep, dreams, age, and fatigue; we believe that we are rather good judges of people’s motives, we have explanations for people’s good memories and abilities, and we have strong positions on the relative influence of nature and nurture in shaping people’s behavior.  Consequently, the expertise of psychologists and human factors professionals are not viewed as based on science.

Six, physical scientists may enjoy the possibility of “testing to destruction” of prototypes or the materials under study, a luxury that experiments on people forbid or are impossible to do outside the safety range allowed by moral standards, laws, and regulations.  Research on people has to circumvent this major difficulty by using dummies, animals, or willing subjects thoroughly aware and educated to the dangers of the procedures.

Seventh, research on people is regulated by privacy laws and concepts such as consciousness, mental images, fatigue, and motives are highly personal experiences and not open to public inspection while science must be a public affair and repeatable by other researchers.