This experiment compared the visual sensory sensitivity of deaf and hearing subjects in a signal detection paradigm. Subjects (ns = 6) were required to give forced-choice responses to a brightness discrimination task under three stimulus probability conditions (0.25, 0.50, and 0.75). A total of 1,800 trials were given to each subject and utilized to construct isosensitivity functions and d' and Beta, indices for sensory sensitivity and response bias, respectively. The results showed that no enhanced sensory sensitivity is present for these deaf children and questions the classical sensory compensation hypothesis. Furthermore, the deaf subjects responded in a relatively bias-free manner to variations in stimulus probability.

A comparison of deaf and hearing subjects on temporal visual resolving power was conducted within a signal-detection paradigm. Subjects were required to make forced-choice judgments of a visual-flicker task under three stimulus probability conditions (0.25, 0.50, 0.75). A total of 600 trials were given each subject from which d' and Beta, indices for sensory sensitivity and response bias respectively, were computed. No significant differences existed on sensory sensitivity or response bias which questions some traditional assumptions about sensory compensation.

The assimilation theory of geometric illusions was employed to explain the reversed ingoing form of the Müller–Lyer illusion. The mathematical formula which was used previously to predict changes in the Ponzo and Poggendorff illusions was employed in simulated experiments on the reversed Müller–Lyer illusion. It correctly predicted the form of the function, relating illusion to size of gap, that was found previously by Fellows (1967). In addition it correctly predicted the effects of increasing the length of the fins on the form of the function. Finally a reversed outgoing Müller–Lyer illusion was found when the outgoing fins were moved towards the center of the shaft.

Temporal auditory sensitivity was compared in five adventitiously blind and five normally sighted subjects in a signal-detection paradigm. Following determination of individual auditory flutter fusion (AFF) thresholds the subjects were required to make forced-choice responses between a fluttering and fused white noise under stimulus probabilities of 0.25, 0.50, and 0.75. From these data indices of sensory sensitivity (d') and response bias (Beta) were computed and compared. Analysis indicated no significant differences in auditory sensitivity between the two groups. These findings further weaken the traditional hypothesis of sensory compensation.

The relationship between apparent size and apparent distance is given by Emmert's law, which states that a retinal image is proportional in size to the distance of the surface it is projected upon. This principle also applies to retinal afterimages in that they, too, will change in apparent size if distance cues suggest that the location of the object onto the retinal image has been altered. It has also been known for some time that non-retinal cues can produce quantitative and qualitative effects on an afterimage when it is viewed in the dark. In the present two studies, positive afterimages of an observer's hand, as well as objects held by that hand, were used as targets to investigate the effects on size-constancy scaling of moving the hand to and fro along the line of sight for different distances in the dark. Results show that, when observers focus on a held object, the changes in size predicted by Emmert's law occur in response to both active and passive proprioceptive or haptic cues. The most intriguing result consisted of the finding that, when only the hand is the target, there appears to be a limit to the decrease in apparent hand size. It appears that the visual system 'refuses' to size-scale the hand below a limit it accepts as representative or acceptable of 'its' hand.