Reaction time as a function of stimulus intensity for the monkey

Monkeys were trained to release a telegraph key in response to a visual or auditory stimulus. The latency of the key release response was measured for different stimulus intensities. In general, the relation between latency and intensity is inverse and exponential with greater variability of latency at the lower intensities. Some preliminary data involving differential reinforcement of short latencies are presented.     

Perceived persuasiveness as a function of response style: Multi-issue consistency over time

This experiment studied the effect of an individual's response style on different issues over a long period of time. A hypothetical situation depicted the repeated responses given by one person on a target issue and on four other issues for one year. The 2 × 2 × 2 factorial design varied consistency of the stimulus person's position on the target issue during the year (consistent or variable); his consistency on other issues during the year (consistent or variable); and social context (alone or dissenting group). Subjects were 155 college students. Results showed an interaction between consistency on the target issue and consistency on other issues for the three dependent measures (p < .001). That is, significantly greater persuasiveness, confidence, and dis-positional causality were attributed to stimulus persons whose opinions were either completely consistent or completely variable on all issues during the year. Results suggest that the consistency of response style across issues—and not the constant advocacy of a specific position–is the crucial factor in the effectiveness of a long-term minority influence.     

Perceived duration as a function of pitch

It was demonstrated with 7 observers that the duration of a high frequency tone was perceived to be longer than the duration of a low frequency tone, even though the actual duration of the two tones was equal.     

Reaction time to a second stimulus as a function of intensity of the first stimulus

Reaction time (RT) to the second of two stimuli presented in rapid succession was examined as a function of the intensity of the first stimulus (S₁). It was found that the delay in RT₂ was greater following a dim first stimulus than following a bright first stimulus. The magnitude of this increase corresponded to the difference in RTs to the two intensity levels of S₁. These results support the prediction of a single channel model of response selection. Examination of mean first RTs revealed a general elevation in latency of RT. However, since this increase was not influenced by the inter-stimulus interval (ISI) or by the intensity of the second stimulus (S₂), and since the same increase was found on “catch trials“ where no S₂ was presented, this increase is considered to be a function of change in set in the double response situation.     

Perceived roughness as a function of body locus

Twenty subjects made magnitude estimates of the roughness of grooved metallic surfaces applied to 10 body loci. To a first approximation, perceived roughness grew as a power function of groove width, in accordance with earlier studies. The exponents and intercepts (up-down position in log-log coordinates) of the power function turn out to depend strongly on body locus. The straight lines in log-log coordinates tend to diverge with groove width so that differences among body loci are especially pronounced at large groove widths. Sensitivity to roughness was greatest for the lips, fingers, and forearm, and least for the heel, back, and thigh. The rank order of the body loci in terms of roughness sensitivity closely parallels the rank order for punctate pressure sensitivity, as reported by von Frey in 1894, but apparently not for other measures of tactile sensitivity, such as vibration thresholds to various frequencies, two-point thresholds, and error of point localization.     

Perceived numerosity as a function of item size

In a sample of 48 subjects, there was a significant inverse relation between item size and estimation of numerosity. This result was shown to be consistent with Gestalt theory. According to this approach, the components of good figures appear more numerous, and smaller items produce better figures.     

Reaction time as a function of the intensity and probability of occurrence of vibrotactile signals

Three Ss made judgments of the presence or absence of a burst of 60-cps vibration onthe index fingertip.The probability of S’s reporting the presence of a signal was found to be influenced by signal probability and signal intensity. Mean reaction time for reporting the presence of a signal decreased as a function of signal intensity and signal probability whereas mean reaction time for reporting the absence of a signal increased as a function of signal intensity and signal probability. On trials where no signal was presented mean R T for reporting a signal decreased with increases in the signal probability whereas mean RT for reporting the absence of a signal increased with increases in signal probability. The results were interpreted as support for the hypothesis that S’s decision time was longer the closer on the sensory continuum a particular observation was to his criterion.     

Perceived velocity as a function of reference mark density

The effect on apparent visual speed of varying the density of stationary reference marks evenly distributed along the path of motion of a point of light was measured using tactile comparison motion. The sensitivity of the tactile method of measuring visual speed was supported by the finding that the tactile measures increased with each increase in physical speed of the point of light, other factors held constant. This procedure was applied in two experiments to visual displays in which the physical speed, extent of motion, and number and density of reference marks was varied. Only reference mark density, in addition to physical speed, was found to be a signficant (and robust) factor in determining perceived speed. The effect of reference mark density is explained in terms of the increasing contribution of relative motion cues to the perception of visual speed as a funciton of the average separation (or average adjacency) of the moving point from surrounding reference marks.     

Color affects perceived odor intensity

In Experiment 1, some odorous solutions (e.g., strawberry) were rated as smelling stronger when colored (e.g., red) than when colorless. Experiment 2 showed this effect to be due to a perceptual change rather than a response to experimental demand characteristics. Experiment 3 showed that the color-induced increase in odor intensity is not due to subjects' preexperimental experience with particular color-odor combinations, because the increase occurred with novel ones. We conclude that color induces a weak olfactory percept that combines with odorant-induced percepts. The effect may be due to conditioning or may be the result of residual intersensory neural connections left over from infancy.