Further developments in binocular summation

This paper reviews experiments that bear on the issue of binocular summation, the superiority of binocular over monocular viewing on various visual tasks covering studies published since the appearance of a previous review of this literature by Blake and Fox (1973). The experiments are grouped into three main categories—those that deal with the specificity of binocular summation (i.e., the extent to which inputs to the two eyes must coincide spatially and temporally), those that study binocular summation on suprathreshold tasks, and those that correlate binocular summation with other aspects of binocular function. The last section of the paper critically reviews several models of binocular summation.     

Binaural summation after learning psychophysical functions for loudness

Do response-related processes affect perceptual processes? Sometimes they may: Algom and Marks (1990) produced different loudness exponents by manipulating stimulus range, and thereby also modified the rules of loudness summation determined by magnitude scaling. The present study manipulated exponents by having a dozen subjects learn prescribed power functions with exponents of 0.3, 0.6, or 1.2 (re sound pressure). Subjects gave magnitude estimates of the loudness of binaural signals during training, and of monaural and binaural signals after training. During training, subjects’ responses followed the nominal functions reasonably well. Immediately following training, subjects applied the numeric response scales uniformly to binaural and monaural signals alike; the implicit monaural-binaural loudness matches, and thus the basic rules underlying binaural summation, were unaffected by the exponent learned. Comparison of these results with those of Algom and Marks leads us to conclude that changing stimulus range likely influences underlying perceptual events, whereas “calibrating” a loudness scale through pretraining leaves the perceptual processes unaffected.     

A distributed intercortical processing of binocular rivalry: psychophysical evidence

When dissimilar visual scenes are viewed dichoptically, the observer perceives several different representations of the scene over time. To reveal that a distributed intercortical network mediates this phenomenon of binocular rivalry, we used a Kanizsa square-like display consisting of four pairs of color-rivalry-inducing elements. We found that when all four dominant elements had the same color, regardless of whether they were from the same or different eyes, the visual system ably integrated them into a larger subjective surface. Once formed, the same-colored subjective surface enjoyed a relatively longer predominance than mixed-colored patterns. During rivalry alternation, this same-colored surface was more likely to be replaced by a complementary same-colored surface, rather than by mixed-colored patterns (cohesive effect). Further, surface integration, which is mainly an extrastriate cortical function, was stronger when the same eye viewed the same-colored rivalry stimuli. Since the eye-of-origin signature is explicitly represented in V1, these findings together suggest that rivalry is processed along a distributed network including V1 and the extrastriate cortices.     

Dichotic, diotic, and monaural summation of loudness: a comprehensive analysis of composition and psychophysical functions

In a series of six experiments, the method of magnitude estimation, constrained by a multivariate model, was used to assess the rules that govern the summation of the loudness of two-tone complexes. This methodology enabled us to specify the amounts of summation and simultaneously to construct the corresponding loudness scales. The components had different frequency separations and in the different experiments were presented (1) dichotically, a different frequency to each ear; (2) diotically, to both ears; and (3) monaurally. Results replicated and in some conditions extended known features of multiple signal processing by the auditory system. Thus, qualitatively different rules of loudness integration appeared. For monaural and diotic modes of stimulation, overall loudness depended on total sound energy within the critical band, but on the simple sum of component loudnesses beyond the critical band. For dichotic presentations, a fully additive rule of loudness summation appeared, regardless of frequency spacing. For the latter (but not the former), loudness summation was perfect, with the underlying loudness scales closely approximating Stevens's sone scale.     

An inquiry into the problem of evil

Paper presented as the invited keynote address at the Society of Clinical Psychologists of Chile Annual Conference, Santiago, Chile, November, 1992.     

The psychophysical nature of humans

Postpowanie czlowieka [Human activity] in [Ajdukiewicz 1985], vol. 1, 317–324.     

An experimental inquiry into transference roles and age

In this psychotherapy analogue investigation, the effects of client age and therapist age on transference-like projections onto therapists were examined. Young (25-35) and older (60-70) pseudoclients compared paraprofessional therapists to significant figures in their own lives after a dyadic "helping" interview. The results provide empirical support for the phenomenon of reverse transference in therapy with older patients. Older clients were more inclined than young clients to view therapists, particularly younger therapists, as similar to their children. Young clients more willingly attributed parental qualities to older therapists. Both old and young clients may see therapists more as peers or friends than as family members.     

An inquiry into the process of temporal orientation.

A recent study (Koriat and Fischhoff 1974) in which subjects were asked to respond to the question ‘What day is today?’ revealed ease of day retrieval to be a curvilinear function of the day of the week, with greatest difficulty being encountered in midweek. Data suggested a twostage model for the day retrieval process, with the weekend serving as a facilitating ‘landmark.’ It was unclear whether these results were due to the day on which the subject was questioned or to the day label which he was requested to produce, the two being completely confounded. In the present experiment, subjects at each of the six working days of two weeks were presented with questions of the form ‘Is today …?’ until 12 correct RT's were obtained for each Actual Day—Proposed Day combination. Major results include significant quadratic effects for Actual Day, Proposed Day and Actual Day—Proposed Day temporal distance; greater latencies for acceptance (‘yes, today is…’) than rejection responses; and details of the weekend effect. The nature of temporal orientation and the role of landmarks are discussed as well as the specifics of the day label retrieval and day label evaluation processes.     

The effects of feedback in psychophysical tasks

Previous results of the reinforcement effects of feedback in psychophysical tasks have been interpreted as changes in the S’s response bias in the uncertain sensory state. The present study varied the percentage of feedback in a two-altemative loud-soft recognition task. The values of the probability of correct feedback were 1, .8, .6, .4, .2, and 0. The results indicated that Ss learned to respond to agree with the experimental feedback rather than with the actual cue presented on a trial. The probability of a response on Trial n +1 was highly dependent upon the response and feedback of Trial n only when the two trials were the same. It was concluded that feedback must influence the response probability vector associated with a given detection state.