Inverse cross-modality matching: A test of ratio judgment consistency for group and individual data

Direct and inverse cross-modality matches made by 20 subjects were assessed for ratio judgment consistency. Each subject matched apparent duration to loudness, and vice versa, in both a directly and an inversely proportional manner. All four tasks were repeated twice so that individual differences could be examined using interrepetition correlations. Group data exhibited the appropriate inverse relationship indicative of consistency, although the inverse matches were slightly curvilinear and resembled earlier studies with inverse attribute scales. Some individuals showed a high degree of consistency but many departed widely from inverse proportionality. Individual differences in exponents, which occurred for both types of tasks, were not removed by S. S. Stevens’ (1971) regression balance procedure. However, interrepetition correlations for the differences in the absolute values of the direct and inverse exponents of individuals were nonsignificant, suggesting that when subjects’ exponents differed for the two types of tasks they did so on a random basis. The latter finding implies that subjects would give inversely proportional matches were it not for random factors. The findings were discussed in relation to other types of ratio consistency.     

Validation of ratio scales of opinion by multimodality matching

Ss adjusted loudness and force of handgrip (and in one experiment apparent duration) to match the strength of their opinions regarding racism, occupational desirability, and pronunciability of trigrams. For each stimulus item, median settings of one continuum were plotted as a function of median settings of the other. The resulting power-function exponents agree with previous cross-modality matches and with the results of a cross-modality match of loudness and duration produced by Ss in the present experiments. The results provide validation of ratio scales of opinion and further establish the direct scalingmethods used to obtain them.     

Intraindividual consistency on a cross-modality matching task

Three observers matched tone bursts and flashes for stimulus magnitude. Matches were made by each observer during 14 sessions over a 2-month period. No intraindividual differences in power function exponents were found. Power function exponents for individuals seem to remain constant across many repetitions of this psychophysical task.     

How repeatable are Stevens’s power law exponents for individual subjects?

Magnitude estimations of apparent length and apparent area were obtained for the same group of Ss over successive experimental sessions. Session-to-session correlations between individual exponents on a given continuum were positive and reliable for successive 24-h intersession intervals, but were not significant for a 1-year interval. In a second experiment on judgments of apparent area, when each stimulus was judged only once per session, the session-to-session correlation was reliable only when the intersession interval was zero. Six other intervals, ranging from 1 to 77 days, yielded nonsignificant correlations. When the constraints exerted by repeated judging are removed, the location of S’s exponent in a distribution of exponents is stable only for brief intervals. Thus the differences among exponents cannot reflect any persisting attributes of Ss’ sensory or judgmental processes.     

Individual differences in power functions for a 1-week intersession interval

Two experiments examined correlations of the power function exponents of individual Ss obtained in each of two sessions. Half the Ss for any task performed second sessions immediately after the first, the other half after a week’s delay. In Experiment I, groups of 16 Ss gave magnitude estimations of apparent area, or else of area and loudness. In Experiment II, groups of 16 Ss made cross-modality matches of apparent time duration to area. Significant correlations in all cases indicated consistent and persisting S differences in exponents. The results are related to the findings of other studies of such individual differences.     

Individual differences in magnitude estimation of loudness

Twenty-two male and female subjects, aged 15 to 31 years, participated in two sessions, 11 weeks apart, of magnitude estimations of loudness. Stable individual differences in the exponent of the psychophysical power law, ψ=k?ⁿ, were shown. The correlation between subjects’ exponents of the first and second sessions was +.59. The generality of these findings and the origin of the individual differences were discussed.     

Constancy of individual exponents for category production of inspired lung volume

Individual exponents for production of inspired lung volume were compared both within experimental sessions (after a delay of 5 to 10 min.) and between sessions (after a delay of 1 yr.). Reliable correlations were observed between pairs of individual exponents regardless of the time elapsed between repetitions of the task. Constancy of exponents may reflect a propensity for subjects to respond in characteristic ways to psychophysical scaling tasks.     

Signal-detection analysis of recognition memory of obese subjects

Obese and normal-weight subjects were run on a series of recognition-memory tasks with low and high meaningful CVC trigrams. Subjects received feedback or no feedback regarding the appropriateness of their answers during testing for recognition memory. A signal-detection analysis was used to examine a relatively pure index of memory (d') as compared to response-bias factors [Ln (beta)]. No significant main effect on memory of obese and control subjects was noted although a significant interaction indicated that obese subjects' memory increases over trials in a differential fashion from normal-weight individuals with poorer performance among the obese after 3 trials. Feedback facilitated memory for both groups. Analysis of response criteria [Ln (beta)] showed no significant difference between groups. Highly meaningful trigrams had a significantly lower response criterion than low meaningful trigrams and there was a significant interaction of meaningfulness by trials. An interaction of feedback by meaningfulness was also present. Advantages of using a signal-detection analysis in memory studies comparing obese and normal weight subjects are discussed. Ramifications of the present data for the internality/externality hypothesis of obesity are also discussed.     

Psychophysical exponents for single papillae: A comparison with whole-mouth exponents

Taste intensity judgments in response to chemical stimulation of single human fungiform papillae were obtained by the method of magnitude estimation. Intensity scales constructed from these data were compared to those obtained from the same subjects in response to stimulation of the whole mouth. Single papilla functions conformed well to the power law governing the growth of sensation magnitude, although a minority of single papilla functions exhibited peaking of response magnitude at intermediate concentrations, followed by a decline in response magnitude at higher concentrations. Single papilla exponents were found to be lower than whole mouth exponents and were positively correlated with detection and/or recognition thresholds of the papillae for most compounds. Exponents of summated single papilla functions were greater than median single papilla exponents, but their relative magnitude vs. whole mouth exponents varied by test compound. The data were discussed in relationship to previous findings concerning flow rate effects, threshold-exponent relationships across the tongue surface, and level-dependent spatial summation.     

SALTNESS, SWEETNESS, AND PREFERENCE: A study of quantitative relations in individual subjects

Individual scales were constructed for saltness and preference in an experiment with eight subjects and for sweetness and preference in a second experiment with seven of these subjects. It was found (1) that power functions described the individual relations between sodium chloride and sucrose concentration, on the one hand, and the subjective variables of saltness and sweetness, on the other hand, (2) that the exponents exceeded 1 but varied greatly between subjects, and (3) that there was a great variation over individuals with regard to the form of the saltness/preference and the sweetness/preference relations.     

REEMERGENCE AND EXTINCTION OF SELF-INJURIOUS ESCAPE BEHAVIOR DURING STIMULUS (INSTRUCTIONAL) FADING

Based on results of a functional analysis indicating that the self-injurious behavior (SIB) of 3 individuals was maintained by negative reinforcement (escape from instructional situations), the effects of stimulus (instructional) fading were evaluated in a multiple baseline design across subjects. The rate of instructions was reduced to zero at the beginning of treatment and was gradually increased (faded in) across sessions as long as SIB remained low. However, if SIB remained high for 10 consecutive sessions, extinction was implemented until SIB decreased, at which point extinction was withdrawn and fading was resumed. Treatment was completed when the rate of instructions was the same as in baseline (two per minute), and SIB remained below 0.5 responses per minute for two consecutive sessions. Results showed that instructional fading (without extinction) virtually eliminated SIB initially, but these effects were not maintained. All 3 subjects required multiple exposures to extinction and over 150 treatment sessions in order to meet the end-of-treatment criteria. Advantages and limitations of fading procedures without an extinction component, as well as extensions of both interventions to other clinical problems, are discussed.     

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.     

The effect of object shape and mode of presentation on judgments of apparent volume

Apparent volume for geometric solids and life-sized two dimensional representations of these solids was scaled by magnitude estimation. Data were adequately fit by power functions whose exponents were less than those previously reported for judgments of apparent length and area. Object shape and mode of presentation affected both magnitude estimations of apparent volume and the best fitting power function exponents. The influence of shape, both across object shape classes and within the cylinder shape class, appears to depend upon the relative elongation of the vertical dimension.     

ASSESSING AND PROGRAMMING GENERALIZED BEHAVIORAL REDUCTION ACROSS MULTIPLE STIMULUS PARAMETERS

Generalization across three stimulus parameters was examined for 5 individuals whose self-injurious behavior was maintained by escape from task demands. Prior to treatment, three stimulus parameters (therapist, setting, and demands) were systematically varied across baseline sessions. These variables were held constant during treatment, which consisted of escape extinction. When treatment was completed, three novel stimulus parameters were probed. If the rate of self-injury was high during this probe, treatment was reimplemented with one new stimulus parameter (the other two were the same as in the original treatment condition). Following this second treatment, another probe with three novel stimuli was conducted. If the rate of self-injury was again high, treatment was implemented again while a second stimulus parameter was changed. This sequence continued until generalization was observed across the three parameters. Results showed idiosyncratic differences in generalization. The behavior of 2 subjects showed complete generalization during the first novel probe. A 3rd subject's behavior showed generalization following treatment across two stimulus parameters (setting and therapist). The behavior of the 2 remaining subjects showed a complete lack of generalization across the three parameters; both subjects required training for novelty by randomly varying the stimulus parameters for a substantial number of sessions.     

Reinforcement as positive or negative meaning-extension: An empirical demonstration

According to logical learning theory, a reinforcement involves the extension of meanings predicated by subjects who are asked to perform in a learning task. Based on this theoretical position, it is predicted that subjects who are administered a reinforcement following their successful anticipation of the second member of a paired-associates unit will acquire their liked trigrams more readily than their disliked trigrams (mixed lists). Conversely, it is predicted that subjects who are reinforced following their incorrect anticipations of the second paired-associates member will acquire their disliked trigrams more readily than their liked. College students (divided equally by sex) were exposed to one of three reinforcement conditions: positive reinforcement, negative reinforcement, and no reinforcement (control). Trigrams reliably rated for likability by each subject were used as learnable materials. Although the control condition did not perform as expected, the remaining experimental conditions support the hypotheses.     

Magnitude estimation of manually assessed elastic stiffness: stability of the exponent

Magnitude estimations were obtained for manual assessments of pure elastic stiffness stimuli (metal springs). 20 subjects of varied experience in manual assessment of spinal stiffness volunteered to participate. The mean exponent of the power function relating perceived magnitude of elastic stiffness to measured physical magnitude was 1.65. Exponents varied across the 20 individuals but were stable across testing sessions held at least 2 weeks apart, and the size of the exponent was not related to prior experience.     

AN ATTEMPT AT EXPERIMENTAL MODIFICATION OF HYPNOTIZABILITY THROUGH REPEATED INDIVIDUALIZED HYPNOTIC EXPERIENCE

In an initial attempt to investigate whether the level of hypnotic susceptibility can be experimentally modified, ten subjects of moderate susceptibility were given individualized hypnotic experience in 4–10 sessions and tested with objective hypnosis scales before and after the experience. Some quantitative and qualitative results are presented. They indicate that in most individuals routinely measured hypnotizability can be changed for the better within a certain range, but that dramatic changes as a rule will not take place.     

Change in action: how infants learn to walk down slopes

A critical aspect of perception–action coupling is the ability to modify ongoing actions in accordance with variations in the environment. Infants’ ability to modify their gait patterns to walk down shallow and steep slopes was examined at three nested time scales. Across sessions, a microgenetic training design showed rapid improvements after the first session in infants receiving concentrated practice walking down slopes and in infants in a control group who were tested only at the beginning and end of the study. Within sessions, analyses across easy and challenging slope angles showed that infants used a ‘braking strategy’ to curb increases in walking speed across increasingly steeper slopes. Within trials, comparisons of infants’ gait modifications before and after stepping over the brink of the slopes showed that the braking strategy was planned prospectively. Findings illustrate how observing change in action provides important insights into the process of skill acquisition.     

Magnitude estimation of apparent sums and differences

Os first scaled two continua by magnitude estimation: apparent area of circles and loudness of 1,000-Hz tones. They then gave magnitude estimations of apparent sums and apparent differences for IS pairs of stimuli on each of the two continua. The scales for sums and differences were in some cases nearly linearly related to the power function obtained when the same as scaled the underlying continuum. However, systematic departure from linearity was the usual result. The power law exponents obtained were generally smaller than those usually reported for the two sensory continua.     

Constrained scaling: the effect of learned psychophysical scales on idiosyncratic response bias

We report seven experiments in which subjects were trained to respond with numbers to the loudness of 1000-Hz pure tones according to power functions with exponents of 0.60, 0.30, and 0.90. Subjects were then presented with stimuli from other continua (65-Hz pure tones or 565-nm lights varying in amplitude) and were asked to judge the subjective magnitude of these stimuli on the same numerical scale. Stimuli from the training continuum were presented, with feedback, on every other trial in order to maintain the trained scale. Except for the 0.90 scale, subjects readily learned the predetermined scales and were able to use them to judge the non-training stimuli with group results consistent with those usually reported. Also, in contrast to the usual magnitude estimation results, these results produced extremely low levels of intersubject variability. We argue that such learned scales can be used as "rulers" for measuring perceived magnitudes, according to a common unit.