The functional architecture of instrumental conditional reflexes

The author holds the opinion that the so-called operant, or instrumental, conditional reflexes, in spite of differences in specific features, do not differ in principle from classical conditional reflexes, and therefore they should not be opposed to them, or be placed in a special or separate group. In support of this opinion, this paper presents data which show that:

1. 1.
   In the establishment of classical and operant conditional reflexes, two-way conditional connections—direct and reverse—are formed.     

Relational perception and modes of perceiver operation

Judgments were made of the size of a small, luminous (inner) square appearing in the center of a somewhat larger, variable (outer) square, the whole pattern appearing in the dark. Accuracy of judgment was greatest when the outer square was constant from trial to trial but deteriorated when the outer square also varied in size, reaching a lower limit less than the accuracy produced under the absolute judgment condition (no outer square presented). An application of multiple discriminant analysis and the use of a maximum likelihood observer model provided estimates of the extent to which Os responded to inner and outer size variation as separate aspects of stimulation. Although Os differed markedly in this respect, their ability to identify inner square size under the various conditions did not reflect this difference.     

Loudness functions under inhibition

In both vision and hearing, a masking or inhibiting stimulus increases the slope (exponent) of the power function that relates sensation to stimulus. The power transformation applies only to the inhibited part of the function where the signal is fainter than the masking noise. Where the signal equals the noise, the function shows a discontinuous knee. Experiments were undertaken to see whether the loudness of a tone of 1000 Hz in a white noise would follow a model based on a constant signal-to-noise ratio at two locations, at the effective threshold and at the knee where the inhibited function meets the uninhibited function. The data accord with the slopes (exponents) generated by the model. The same model gives a fairly good account of the recruitment functions for ears suffering from cochlear involvement (e.g., Méniere’s disease). Regardless of degree of hearing loss, loudness recruitment reaches normal when the tone (1000 Hz) is about 30 dB above the affected threshold.     

Some observations and measurements of the Pulfrich phenomenon

The Pulfrich pendulum was evaluated as a potential screening device for the detection of anomalies of binocular vision. For this purpose, a booth was set up at the Kentucky State Fair (1964) and the general public invited to observe the pendulum and record their responses with the equipment provided. The obtained results indicate that a dichotomy can be achieved between those who have binocular vision and those who do not. However, gradations of binocular vision from poor to good cannot be achieved with the pendulum as presently understood. Contrary to explanatory theory the characteristic shape of the seen pendulum path was asymmetrical following the rule that the path was displaced away from the observer on the side of the filtered eye.     

The effect of angle between the oblique lines on the decrement of the Müller-Lyer illusion with extended practice

Early work on the Müller-Lyer illusion had indicated that it disappears with extended practice. The present experiment failed to confirm this finding. The magnitude of the illusion decreased for approximately 500 trials, but showed no further change over an additional 500 trials. The rate of the practice decrement was inversely related to the size of the angle formed by the oblique lines of the figure.     

The effects of variation of intertrial interval on exploration of elevatd and enclosed mazes

The interval between exploratory trials was varied in experiments using simple elevated or enclosed mazes. Activity on the second trial was depressed for short intertrial intervals but had recovered after about 10 min.; the degree of recovery was different in the two types of maze. A second decrease in second trial activity was found with inter-trial intervals of more than 20 min., but a further experiment suggested this was due to the effects of delay itself, rather than to previous experience of the environment.     

Population norms of top sensory magnitudes and S. S. Stevens’ exponents

If S. S. Stevens’ exponents indicate the rates at which sensations grow with increases in sensory intensity, they ought to correlate with the population norms of top sensory magnitudes. Using a comprehensive sample of eight sensory dimensions, the tau coefficient of rank correlation between Stevens’ exponents and the medians of the top sensory magnitudes reported by 305 observers was found to be only +.15 (p>05). With the geometric means tau fell to ?.04. A split-half consistency check on the medians of the population norms suggested that they were not to blame for the low correlation. Direct comparisons of pairs of sensory dimensions on 146 additional observers produced results which confirmed the population norms. Since there is no way of comparing most of the top physical stimuli experienced in everyday life, it is not possible to make a joint prediction from exponents and top stimuli. S. S. Stevens’ exponents thus appear to have little predictive value outside the experimental conditions under which they were measured.     

The use of extreme groups to test for the presence of a relationship

Experimenters in psychology frequently investigate the relationship between two variables by selecting extreme groups on the first measure and comparing their mean scores on the second. This paper considers the efficacy of this procedure from the criterion of the power of the statistical tests. Optimal cutting points for the extreme groups are defined, and the power of the difference approach is compared to that of significance tests for the productmoment correlation coefficient.