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Frequently Asked Questions

I have been often grilled about my background by cross-examining attorneys who were in a state of shock upon being told that psychologist could be an expert in human factors, vision or lighting without being an engineer or a medical person. When people hear the word "psychologist," they immediately think, "shrink." In fact, only 50-60% of psychology Ph. D.'s are clinicians, people who deal mental conditions and the like. The rest are spread across a wide range of scientific and applied areas. Experimental psychologist is the largest group of nonclinicians1.

I am not really surprised because most people have little familiarity with experimental psychology as a scientific discipline. They know an engineer or have gone to an ophthalmologist so they understand these experts. But few have ever met an experimental psychologist. I frequently find that attorney's were completely unaware that people like me exist - a scientific human factors expert.

As an aid to future cross-examining attorneys, I propose to simplify their lives by giving the answers to the usual questions up front. I describe my background as an experimental psychologist explain the differences (and many similarities) between our expertise and that of people in related fields. I conclude with the answers to a few other common questions about my background. Other Frequently asked questions 1. What is an experimental psychologist?

Experimental psychologists are scientists who have studied human behavior and have learned to design, perform and analyze scientific research2. They initially learn topics such as experimental design and statistics as well gain a general background in topics such a perception, cognitive psychology and learning. They specialize in one of these area or more of these area perform a master's thesis research project. (Mine, for example, was reaction time and learning). They then continue to take more specialized courses in their area of concentration and perform a doctoral thesis. (I switched to vision for my Ph. D.) After gaining a Ph. D., experimental psychologists who want to continue with a research career will further their education with postdoctoral study. (I did that at Brown University and the University of California at Berkeley.)

2. What is the relationship between experimental psychology and human factors?

Human factors is defined as "the application of scientific data to make the world compatible with human abilities, fitting the product to the sensory, information processing, and motor attributes of the user." As result, human factors experts must be know all three fields. Human factors was not a degree field until relatively recently, so most human factors experts, and virtually all over the age of 45, have their roots in another discipline. The "sensory, information processing, and motor attributes" of people are all topics that most experimental psychologists will have studied extensively, so it is hardly surprising that many human factors experts were trained as experimental psychologists.

It may surprise the many people who believe human factors to be an engineering field that experimental psychologists make up the largest single membership group in the Human Factors and Ergonomic Society, the main professional human factors organization in America.

3. What is the difference between an experimental psychology and an engineering human factors experts?

Human factors is a mix of psychology and engineering. In most cases, a human factors analysis requires two steps. The first is to specify the physical properties of a situation, e, g, the speed and distance of vehicles in a road accident. The next is to determine how human limitations and predispositions would operate under the physical, situational constraints, e .g., reaction time, perception, decision-making.

Because of its interdisciplinary nature, most human factors experts come from both psychology or from and engineering. However, there is a strong difference in emphasis. The Engineer's base of knowledge and expertise is in the physical specification. Their basic education is in math, physics and related topics. An experimental psychologist's base of knowledge and expertise is in the science of human behavior. Their basic training is in the scientific method and basic psychological factors, such as perception, memory, cognition, learning, etc. While engineers are primarily taking math physics and engineering courses, experimental psychologists are studying perception, memory, learning, cognition and experimental design and statistics. In questions of human behavior behavior, the psychologist is far more likely to have greater breadth and depth of knowledge, to be far more familiar with the research literature and to be better schooled in scientific first principles. After all, it is the psychologist's main business - not engineering.

Lastly, the distinction between engineers and experimental psychologists is hardly absolute. Although not a basic part of their training (with the exception of industrial engineers), some engineers learn more about behavior through their career while experimental psychologists learn some engineering. My research, for example, has included applications of engineering math, such as linear systems analysis, sampling theory, and Baysean modeling. I have also done accident reconstruction calculations.

4. What is a "Visual Psychophysicist?"

Despite its rather zen sounding name, "psychophysics" is about as hardcore as science gets. It is the scientific study of the senses and is the scientific home of people who are experts in visibility and similar issues. The term "psychophysics" literally means the relationship between the physical world and the psychological world. Visual psychophysics experts are part psychologist and physiologist on the one hand and part physicist (on the properties of light) on the other. As a psychophysicist, I must have good knowledge of lighting to do my job. I have frequently, for example, made lighting measurements and calculations.

The topics covered by visual psychophysics are wide ranging. The most basic are contrast detection visibility and acuity. However, visual psychophysics also examines many other visual abilities, including judgments of motion, size, brightness, distance, depth, color, etc. There are many other topics that bleed into psychophysics from cognitive psychology and physiology, including attention, conspicuity, eye movements, memory, information-processing and response.

5.What is the difference between and experimental psychologist (Ph. D.) and an optometrist (O. D.) or ophthalmologist (M. D.)?

The first time that I testified in court the issue was whether a driver flunked a sobriety test because he was drunk or because he had a congenital nystagmus (involuntary eye movements). The cross-examiner grilled me extensively about my lack of a medical degree. After the trial was over (and the defendant acquitted), the same cross-examining attorney came up to me and said, "Hey Doc, I've been having some trouble with my left eye. What do you think's the problem?"

I've come to expect the grilling, if not the request for free medical advice. Cross-examiners like to have me admit that I do not have a medical degree. I do so gladly! They are under the false impression that vision (and many other areas such as motor control) is a medical field. In fact, visual science is a huge, interdisciplinary field that includes people from a wide range of backgrounds. The expertise of M. D.'s and O. D.'s. diagnosing and treating eye diseases, is merely a subspeciality within the world of visual science. Any scientific vision meeting is likely to have papers from experimental psychologists, engineers, physicists, biologists, computer scientists, physiologists and possibly optometrists and ophthalmologists. Likewise, vision papers appear at many different conferences; I have given many papers. for example, at the Association for Research in Vision and Ophthalmology meeting, The American Psychological Association meeting, the International Society for Optical Engineering meeting, Human Factors Society meeting, etc.

An O. D., a M.D. and a Ph. D. (in visual psychophysics) all have expertise in vision, but with different emphases. The criterion for receiving a Ph. D. is the ability to perform independent research on visual capacity while criterion for receiving a medical degree is the ability to diagnose and treat eye diseases. A Ph. D. is primarily a research degree for people who want to study normal vision and the mechanisms underlying normal vision. The O. D. and M. D. are clinical, not scientific degrees. Their focus is diagnosis and treatment of eye diseases and not research. Further, they primarily are experts in limited areas of vision, principally those that are governed by the visual optics, the retina and proper alignment of the eyes.

However, the distinction between medically and research trained experts is hardly absolute. A few optometrists and ophthalmologists go into research and some even getting a Ph. D. on top of their medical degree. Although most study eye diseases, some work in basic the same basic areas as Ph. D.'s. Similarly, some Ph. D.'s become interested in eye disease, research abnormal vision may even become faculty members in Optometry and Ophthalmology departments. They do not diagnose and treat patients (although they may perform clinical testing) but rather perform research to investigate the underlying causes and effects of the eye disease. They may even become faculty members in a medical or optometry school. For example, I have been a university faculty member in both optometry and ophthalmology and have done research on glaucoma, ambylopia and aging vision.

In sum, I am as qualified, and frequently more qualified, than medical experts to opine about human visual performance abilities. Most real-world seeing depends on factors such as attention, memory and learning, topics that medical people generally do not study. The main visual topics that are outside my expertise include diagnosis and treatment of an eye disease. Given a proper diagnose from a medical professional, however, I am qualified to give opinion on how that abnormality will affect seeing.

6. What is the difference between a visual psychophysicist and a lighting engineer or architect?

Lighting design involves two stages: 1) determining the light required by people to perform tasks in a particular environment and 2) determining the means for creating the required lighting. The first requires expertise in human vision and cognitive psychology is and is therefore primarily a matter of visual human factors. The second is a matter a engineering and of lighting design. Once the requirements are established, architects and other lighting designers are expert in creating an environment that meets these needs. However, they are not necessarily experts in setting or evaluating the needs or analyzing how the existing conditions may have affected visual abilities. Although they may have some knowledge (they have undoubtedly taken a course or two) in the area, they are not typically experts in vision or perception (there are exceptions). Moreover, the codes and recommendations that govern lighting design are seldom the result of detailed analysis of visual factors - they are typically a compromise among conflicting demands of safety, aesthetics, pragmatics and cost.

7. Why do you handle cases in such a wide range of areas?

My specialty is vision, perception, attention, memory and response. Virtually all human activities, e .g., driving a car, seeing warning, walking down stairs, remembering and event, buying a box of candy, require a person to use his eyes in order to gain and process information about the world, to make decisions and to act. The perceptual processes in the head remain invariant across all of these situations, so the same expert knowledge applies.

8. Are you far away?

Although I was born, raised and educated in the US, I live in Canada. (This is where my wife and her family are from.) Some people seem to think that Canada is a far away country, just next to the North Pole. In fact, Toronto is only a few miles across the lake from Buffalo, New York. Because the Toronto Pearson airport serves a metro area of 5 million people, it has excellent air connections to just about anywhere in North America. If travel requires a plane ride, there is no practical difference between originating in Toronto and in Buffalo, Detroit, Pittsburgh, or another northeast/midwest US city.

9. What is your case experience?

I have been retained in about 90 cases, with a breakdown of 55% plaintiff and 45% defense (counting the prosecution side of criminal cases as plaintiff). I have testified 19 times.


1Other types of non-shrink psychologists include those who work in industrial/organizational psychology, Neuropsychology, behavioral medicine, educational psychology, school psychology, behavioral pharmacology, environmental psychology, exercise and sport psychology, consumer psychology, police psychology, physiological psychology, etc. Some of these areas overlap with experimental.

2By scientific research, I mean using using the methods of science: controlled observation (clearly identify the factors - independent variables) which produce observable behavior), quantifyable, reproducible results (dependent variables), etc. The core expertise of any scientist, whether biologist, chemist or experimental psychologist, is the ability to plan, to conduct and to analyze research, and the ability to read, interpret and evaluate research by other other people in his own and related fields.

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