Instructions and Knowledge of the Situation in Brightness Perception

Abstract

The influence of information and instructions on brightness perception was investigated under conditions where either ratio or retinal matches were possible. Unlike most earlier studies, this one found no effect of experience: both trained and control groups showed identical ratio responses. The importance of obtaining perceptual rather than cognitive reports is emphasized in accounting for the contradictions in the literature. Experience and training have been shown to influence the perception of shape, size, and brightness.1 It is of particular note that constancy for each has also been shown to be affected by instructions requiring observers to make retinal rather than phenomenal reports of their observations.2 The susceptibility of such basic phenomena to learning has been argued strenuously by the transactionalists and to a lesser degree, by gestaltists as well.3 But it is Received for publication July 22, 1969. 1 On shape, see P. K. Leppmann and R. B. Mefferd, Jr., Validity of perceptual reports of experienced and inexperienced observers, Percept. mot. Skills, 26, 1968, 1167-1172; R. B. Mefferd, Jr., Betty A. Wieland, D. G. Greenstein, and P. K. Leppman, Effects of pretraining and instructions on validity of perceptual reports by inexperienced observers, Percept. mot. Skills, 27, 1968, 1003-1006. On size, see H. R. Schiffman, Size-estimation of familiar objects under informative and reduced conditions of viewing, this JOURNAL, 80, 1967, 229-235. On brightness, see R. G. Hopkinson, An experiment on the assessment of brightness under 'free-choice' and 'forced-choice' conditions by a group of observers, Ergonomics, 3, 1960, 44-50. 2 A. A. Landauer, The effect of instructions on the judgment of brightness, Quart. J. exp. Psychol., 16, 1964, 23-29; A. A. Landauer and R. S. Rodger, Effect of apparent instructions on brightness judgments, J. exp. Psychol., 68, 1964, 80-84; M. Parrish and K. Smith, Simultaneous brightness contrast as a function of perceptual set, Psychon. Sci., 7, 1967, 155-156; A. A. Landauer, Influence of instructions on judgments of unfamiliar shapes, J. exp. Psychol., 79, 1969, 129-132; W. H. Lichte and C. R. Borresen, Influence of instructions on degree of shape constancy, J. exp. Psychol., 74, 1967, 538-542; V. R. Carlson and E. P. Tassone, Size-constancy judgments at equal distances, Percept. mot. Skills, 27, 1968, 193-194. The terms used in the instructions of these studies to contrast the two attitudes have included: analytic, critical, objective, physical, projective, real, vs. apparent, immediate, naive, perceived, synthetic, whole. 3 On the transactionalists, see W. H. Ittelson, The constancies in perceptual theory, Psychol. Rev., 58, 1951, 285-294; W. H. Ittelson and F. P. Kilpatrick, Experiments in perception, Sci. Amer., 185, 1951, 50-55; F. P. Kilpatrick and W. H. Ittelson, The size-distance invariance hypothesis, Psychol. Rev., 60, 1953, This content downloaded from 157.55.39.114 on Mon, 25 Apr 2016 06:56:53 UTC All use subject to http://about.jstor.org/terms NOTES AND DISCUSSION 131 surprising to find brightness included among those phenomena shown to be affected by experience. MacLeod's early investigation did not find it so, nor would such an effect seem consistent with the great body of work which places brightness perception within a psychophysical framework.4 Furthermore, in contrast to shape and size, brightness is thought of as being more stimulus-bound and dependent upon retinal factors. Thus, the treatment of brightness and brightness constancy as a function of ratios of intensities explicitly rules out the traditional explanation of 'taking illumination into account,' i.e. denies the role of knowledge. Finally, everyday observations of objects in different illuminations (and the observations in the Gelb and Katz demonstrations) do not appear to be events easily amenable to phenomenal change as a result of knowledge of the situation or of conscious attempts to reverse one's percept.7 The purpose of this study was to investigate whether maximizing observers' critical understanding and approach to a brightnessperception task would indeed lead to a change in the outcome. To this end, two groups differing in their knowledge of the situation and in their instructions were asked to make brightness matches under ratio conditions of illumination. Thus, the structural factors thought responsible for brightness perception would be shown to persist if observers made ratio rather than retinal matches despite circumstances which favored the opposite result.