Phenomenology and psychophysics

Recent philosophy of mind has tended to treat “inner” states, including both qualia and intentional states, as “theoretical posits” of either folk or scientific psychology. This article argues that phenomenology in fact plays a very different role in the most mature part of psychology, psychophysics. Methodologically, phenomenology plays a crucial role in obtaining psychophysical results. And more importantly, many psychophysical data are best interpreted as reporting relations between stimuli and phenomenological states, both qualitative and intentional. Three examples are used to argue for this thesis: the Weber–Fechner laws, the Craik-O’Brien–Cornsweet effect, and subjective contour figures. The phenomenological properties that play a role here do so in the role of data that ultimately constrain theoretical work (in this case theory of vision), and not as theoretical posits.     

Memory psychophysics

Summary The relationship between perceptual and cognitive processes has been a topic of increasing interest. This review focuses on the use of techniques and theory drawn from classical psychophysics and applied to the study of mental representation. Several issues including examination of the functions that relate remembered and perceived magnitude to physical intensity, the relationship of memorial to perceptual functions, the effect of time on the memorial function, considerations in the methodology of memory psychophysics experiments, the level of functional equivalence between memorial and perceptual representation, and the use of psychophysical techniques and theory in the study of visual imagery are addressed. While the data suggest that the relationship between remembered magnitude and physical intensity and between perceived magnitude and physical intensity can be described by power functions, a model capable of accounting for the behavior of the memory magnitude for all stimulus dimensions and at all time intervals has not yet been found. Several unresolved issues and typical difficulties with research in memory psychophysics are also discussed.     

Ibn al-Haytham and psychophysics

Persian scholar Ibn al-Haytham ('Alhazen') has rightly been credited with many advances in optics and vision science, but recent spurious claims that he is the 'founder of psychophysics' rest upon unsupported assertions, a conflation of psychophysics with the wider discipline of psychology, and semantic arguments over what it is to 'found' a school of thought.     

The psychophysics of imagery

A series of experiments considers the extent to which the interrelations among subjective magnitudes aroused by images corresponds to those for subjective magnitudes aroused by physical stimuli. In Experiment 1,68 undergraduates typed phrases in response to graded categories regarding the imagined magnitude of lights, sounds, and smells. In Experiment 2,5 undergraduates and, in Experiment 3, 3 graduate students then magnitude estimated the image intensity aroused by each of these stimulus phrases. In Experiments 4 and 5, the same subjects performed cross-modality matches between phrases arousing images for different attributes (light, sound, and smell). Statistical analysis indicates that estimates based on images display many of the same patterns as those based on physical stimuli. The major exception involves sequence effects, present for actual stimuli but not for images.     

The psychophysics of spending

Several theories of decision making are based, in part, upon the principles of psychophysics (Kahneman and Tversky, 1979; Thaler, 1985). For example, due to the psychophysics of quantity, the difference between $10 and $20 seems greater than the difference between $110 and $120. To determine whether psychophysics influences consumers' decisions, subjects in four studies made real or hypothetical purchases. It was predicted that as the size of the purchase increased, subjects would be more willing to buy additional smaller items. Small extra purchases should seem like minor expenditures when they follow larger purchases. Results of the four studies supported our hypothesis. In addition, it was found that subjects responded not only to actual changes in purchase size but also to changes in the presentation or framing of a purchase.     

The psychophysics of imagery

A series of experiments considers the extent to which the interrelations among subjective magnitudes aroused by images corresponds to those for subjective magnitudes aroused by physical stimuli. In Experiment 1, 68 undergraduates typed phrases in response to graded categories regarding the imagined magnitude of lights, sounds, and smells. In Experiment 2, 5 undergraduates and, in Experiment 3, 3 graduate students then magnitude estimated the image intensity aroused by each of these stimulus phrases. In Experiments 4 and 5, the same subjects performed cross-modality matches between phrases arousing images for different attributes (light, sound, and smell). Statistical analysis indicates that estimates based on images display many of the same patterns as those based on physical stimuli. The major exception involves sequence effects, present for actual stimuli but not for images.     

The psychophysics of contingency assessment

The authors previously described a procedure that permits rapid, multiple within-participant evaluations of contingency assessment (the "streamed-trial" procedure, M. J. C. Crump, S. D. Hannah, L. G. Allan, & L. K. Hord, 2007). In the present experiments, they used the streamed-trial procedure, combined with the method of constant stimuli and a binary classification response, to assess the psychophysics of contingency assessment. This strategy provides a methodology for evaluating whether variations in contingency assessment reflect changes in the participant's sensitivity to the contingency or changes in the participant's response bias (or decision criterion). The sign of the contingency (positive or negative), outcome density, and imposition of an explicit payoff structure had little influence on sensitivity to contingencies but did influence the decision criterion. The authors discuss how a psychophysical analysis can provide a better understanding of findings in the literature such as mood and age effects on contingency assessment. They also discuss the relation between a psychophysical approach and an associative account of contingency assessment.     

Virtual reality and the new psychophysics

Virtual reality (VR) promises methodological rigour with the extra benefit of allowing us to study the context-dependent behaviour of individuals in their natural environment. Pan and Hamilton (2018, Br. J. Psychol.) provide a useful overview of methodological recommendations for using VR. Here, we highlight some other aspects of the use of VR. Our first argument is that VR can be useful by virtue of its differences from the normal perceptual environment. That is, by virtue of its relative non-realism and poverty of its perceptual elements, it can actually offer increased clarity with respect to the features of interest for the researcher. Our second argument is that VR exerts its measurable influence more by eliciting an acceptance of the virtual world (i.e., ‘suspension of disbelief’) rather than by eliciting a true belief of the realism of the VR environment. We conclude by providing a novel suggestion for combining neuroimaging methods with embodied VR that relies on the suspension of disbelief.     

The psychophysics of iconic storage

Some simple models of iconic storage, based on the persisting responses of photoreceptors, were tested in two experiments. Substantial changes in such physical parameters as adapting luminance, stimulus luminance, and stimulus contrast produced little or no change in the duration of partial-report performance. This is at odds with most receptoral models. It seems unlikely that any model based on receptoral persistence can accommodate the results, thus forcing one to locate the icon beyond the receptors and probably beyond the retina as a whole.     

The psychophysics of retrospective and prospective timing

In two experiments, different groups of subjects heard four musical selections and then estimated the duration of each selection. Some groups made retrospective time estimates while others made prospective estimates. In both experiments, analyses of the psychophysical relation between perceived and actual duration showed that the slopes of straight-line fits were flatter and accounted for a smaller proportion of the variance under retrospective as compared with prospective conditions. In addition, in experiment 1, retrospective subjects were less accurate in rank ordering the selections from longest to shortest. There was also a serial-order effect, with selections estimated longer when they occurred early in the sequence. In experiment 2 the slopes decreased as the selections in a series became longer. Both retrospective and prospective estimates also exhibited a context effect, in that estimates of a given selection were influenced by the relative durations of the other three selections in the series. The results on inaccurate retrospective judgments raise questions about prior research on stimulus factors and retrospective timing. However, similarities under retrospective and prospective conditions suggest that timing under these conditions, although different in some respects, reflects a similar process.     

Stimulus programming in psychophysics

Summary and Conclusion The major thesis of this paper has been that one should choose a psychophysical method appropriate to the question which prompted the inquiry. It has been suggested that the method of constant stimuli, although not inappropriate for most questions, is by no means optimal for any particular question. A class of stimulus programming techniques called Markov designs has been briefly described. These have the principal advantage of using data as it is gathered to improve the selection of stimuli for the remainder of the experiment. This improvement is achieved by concentrating observations in the region of most interest. They are also reasonably easy to carry out and can be tailored to a wide range of experimental objectives, and pose no new problems in data analysis.Finally data analysis is discussed. It is pointed out that the question of which mathematical form to use in graduating the data is a minor one if the data are efficiently gathered and that, within reason, mathematical convenience is a good criterion. An advantage of the logistic function over the normal ogive is mentioned.Few of the ideas advanced here are new but many have not been appreciated fully by psychophysicists. The emphasis in this paper has been on the areas of sensitivity testing in which psychophysics has lagged behind best statistical practice, although it was pointed out that no efficient methods of analysis of the continuous response procedures have yet been devised by the statisticians. Better communication in both directions is clearly desirable.Operated with support from the United States Army, Navy, and Air Force.     

Fechner's "inner psychophysics"

Though psychologists are generally aware that Gustav Fechner introduced psychophysics and set down its essential methodology, most of them only know about the part that Fechner called "outer psychophysics." In his classic publication of 1860, Fechner insisted that "inner psychophysics" was more important, yet this aspect of Fechner's work failed to receive any attention. The article reviews Fechner's presentation of inner psychophysics and suggests reasons why that part of his work was neglected and has been forgotten.     

Memory psychophysics for visual area and length

Independent groups of observers made magnitude estimates of geographical area or interstate distance. In Experiment 1, observers estimated the areas of nations or of states of the United States from memory. In Experiment 2, estimates of state area were made either with a map present or from memory after the map had been studied. Similarly, in Experiment 3, observers made perceptual or memorial estimates of interstate distances. Perceptual estimates of distance and geographical area were related to actual stimulus magnitude by power functions whose exponents were similar to those found with conventional procedures. Memory estimates were also related to actual area and distance by power functions. Comparison of memory and perceptual exponents showed that for both area and distance, the memory exponent was equal to the square of the perceptual exponent. The results of Experiment 3 were predicted by a “re-perceptual” model of memory for continuous dimensions, which was developed to describe the results of Experiment 2.     

Reversed dimensional analysis in psychophysics

It is argued that dimensional analysis (from physics) can be applied in psychophysics in the same manner as in physics, provided that the dimensions of sensations are interpreted in the sense of reversed dimensional analysis, which allows for extracting dimensions from data. A dimension obtained by this method, referred to as phenomenological dimension, is similar to a fractal dimension. The examples discussed show that, if the dimension of sensation in Stevens' psychophysical law for time duration (psi = Cphin, n approximately 1.15) is interpreted as a phenomenological dimension, such a dimension can be traced even in short-term memory data. It is suggested that dimensions obtained via reversed dimensional analysis may serve as a link between physical and psychological variables and as a basis for developing the notion of dimension in psychology.