The Neurophysiology and Psychophysics of Visual Perception

Abstract

The Greco-Roman civilization, referred to as the period of classical antiquity, spanned from about 800 bc to ad 500. The Greek followed by the Roman philosophers began to develop a science of optics in their investigation of the natural sciences. However, the philosophers of that era were highly religious and that influenced the science developed, which was quite affected by spiritual and religious beliefs rather than by experiment, measurement, analysis, and then determination of only the facts. However, that is easier said than done for the philosophers were developing theories, initially from a void. In the period from about 440 bc to about 270 bc, Democritus followed by Epicurus concluded that for the eyes to see an object it had to come into physical contact with the eye by pressing the air between the eye and the object, so transmitting its color and shape to the eye. This is called the “intromission theory.” However, in a variation of that intromission theory, Epicurus was of the opinion that it was not the compressed air between the object and eye that resulted in vision, but particles from the object traveling to the eyes. He hypothesized that produced vision by gradually shrinking objects through particles from the object filling the empty spaces in the object. Still, it was an intromission theory (Ackerman 1978).

Appendix 11

11.1.1 Specific Research Area of Architectural Psychophysics

The general esteem and assessment of any architecture depends a great deal on its visual image, perception of its exterior, and impressions during the visit to its interior. The designed or already realized architectural concept of the overall architectural space and its functional and esthetic structure and form as well as the human (architectural) environment created are evaluated visually by investors, the general public, and each inhabitant or owner. As a consequence of such attention to “visual appraisal,” several subjective appraisal studies of exterior or interior architectural spaces and their environmental influences were developed on the basis of psychological or psychophysical measuring methods.

In experimental psychology, factor analysis was applied, based on clearly identifiable evaluative polar scales expressed by adjectives with selective and high loading or meaning for the assessed object. Originally, such analysis was proposed by Thurstone (1948) and was later used by Osgood et al. (1957) with the semantic differential or judgment of subjectively felt meaning on a series of descriptive scales of a questionnaire-based experiment. Further studies have shown that people in over ten different language and cultural communities use quite similar semantic factors of the most salient type in meaningful judgment areas of evaluation, potency, and activity. A more sophisticated theoretical structure (Harman 1960) and application to architecture studies as by Vielhauer (1965) and Hershberger (1968) opened new possibilities of measurement of human responses to buildings and their interiors. A very important property of a building is its ability to provide an appropriate space and environment for its users, who are able to express their satisfaction or dissatisfaction (Canter 1968). Two experiments with architecture and nonarchitecture student groups by Canter (1969) indicated in the judgment of black and white slides of 20 building shown that from 45 adjective bipolar scales, the most relevant and meaningful considered were the factors of character and friendliness, coherence, and activity. In accordance with these findings, an ideal “friendliness” scale was adopted with the dichotomization points (Table A11.1) for subject sensitivity and satisfaction with different building types or designed alternatives (Canter and Wools 1969). This scale was used in a pilot study (Kittler and Wools 1969) in which an interior was shown to subject groups on slides in color, black and white, and with line drawings. The same interior was varied, presenting two seating arrangements, two window types, and a flat or sloping ceiling. Even more suitable ten bipolar semantic differential scales were applied to assess interior appearance (Loe et al. 1994, 2000). Unfortunately, no preference studies concerning windows, their size, and their placement under typical daylight conditions were made. Detail experiments structured to test if the provision of a view both in drawings and in models does affect the ratings of windows were included in psychophysical studies (Néeman and Hopkinson 1970; MacGowan et al. 1984).

Table A11.1 An example of a bipolar scale with dichotomization points for evaluating scores

In a different research area, on the experimental studies is the subjective rating of the dimensions of architectural spaces. Original experiments by Gilinsky (1951) have shown that the perceived size and distance of objects in the visual space are distorted. Exterior architectural spaces were compared subjectively as seen and drawn by architecture students with objectively measured dimensions (Koroyev and Fedorov 1954; Fedorov and Koroyev 1961). When these results were analyzed, the similarity with Stevens’s power law was evident (Kittler 1968) and close to findings by Gilinsky. For instance, the subjectively perceived distance in nature $d$ is related to the real distance $D$ in meters:

$$ d = 1.24{D^{{0.866}}}. $$

(A11.1)

The height of buildings (house front or spires) ($h$) is seen to be even more distorted in comparison with actual height $H$ measured in meters as

$$ h = 1.48{H^{{0.866}}}, $$

(A11.2)

if $H \ge 30\;{\hbox{m}}$.

So, the proportion $h/d$ seems to be

$$ \frac{h}{d} = 1.2{\left( {\frac{H}{D}} \right)^{{0.866}}}. $$

(A11.3)

The third group of psychophysical scaling uses an arbitrary numbered scale for subjectively felt just noticeable differences (jnd) related to the physically measured ratio. In this area is also the multicriterion scale of glare which causes visual discomfort without necessarily impairing the vision of objects (Hopkinson 1950, 1957, 1963 and Hopkinson et al. 1971). For the discomfort glare index (${\hbox{GI}}$), changes were determined by RGH fixed reference values representing Hopkinson’s multicriterion scale points:

• Just perceptible with ${\hbox{GI}} = 8$

• Just acceptable with ${\hbox{GI}} = 15$

• Just uncomfortable with ${\hbox{GI}} = 21$

• Just intolerable with ${\hbox{GI}} = 28$

These first critical points roughly correspond to the straight line on Stevens’s S sensation curve for average observers (Hopkinson 1957).

Further details and progress in glare determination are given in Chap. 12.