Visual orientation estimation

A systematic error is reported in orientation estimation, in that on average, estimates are closer to the vertical axis than are the stimuli by up to 6°. This systematic error results from a specific mechanism that may be related to depth perception, and that is avoided in certain circumstances or when other mechanisms take over. For example, the estimates of one observer who was a welltrained professional draughtsman did not show this systematic error. Furthermore, for all observers tested, estimation of clock time is not subject to the regular orientation estimation error. Rather, observers tend to estimate timesas slightly further from the quarter hour than they really are. Orientation judgment channel capacity was also studied under various conditions. The number of discriminable orientations is far above the magic number “7“ limit, reaching over 20 in optimal circumstances. The distribution of discriminable orientations is nonlinear, in that these are more closely packed about the horizontal and vertical axis than at the oblique.     

The effect of instruction with relational and item-specific elaborative strategies on young children's organization and free recall

One hundred and sixty second-grade children were assigned on the basis of a free recall pretest to four instruction conditions and were given a series of lists of pictures for free recall. For three groups, the instructions were directed at encoding either (a) list organizational information, (b) item-specific semantic information, or (c) organizational and individual item information, while the fourth group constituted a “No-training” control with standard free recall instructions. The subjects received either related or unrelated lists during the training phase and related or unrelated lists during two post-tests, immediately following and 1 week after training. For both types of lists, instructions emphasizing list organization were more effective than those emphasizing item-specific elaboration. Subjects given individual item elaborative instructions showed levels of recall which were comparable to those of the control subjects. While the combined effect of organizational and individual item processing did not exceed the performance produced by organizational instructions alone, the degree of generalization was greater for subjects processing both kinds of information, especially when subjects received related lists during training.     

A simplification of a completeness proof of Guaspari and Solovay

The modal completeness proofs of Guaspari and Solovay (1979) for their systems R and R ^– are improved and the relationship between R and R ^– is clarified.     

Effects of nitrous oxide on reactions to “stress”

It has been demonstrated that exposure to the stress of a situation involving conflict or frustration may interfere significantly with subsequent learning. Behaviour under stress is characterized by experiences of “anxiety” and by widespread physiological changes. Inhalation of nitrous oxide has the general effect of reducing the extent of these symptoms.

The present investigation using insoluble and soluble problems has demonstrated that both nitrous oxide and exposure to stress impair learning; but that, when subjects are exposed to stress while under the influence of the drug, the effects of the stress on subsequent learning are abolished. It is suggested that these empirical results may be accounted for either in terms of “anxiety-reduction” or in terms of transfer effects.     

A simple decoder arrays to a for linking photocell microcomputer

Inputs from photocell arrays (such as those incorporated in mazes) to a microcomputer must be decoded. For up to 31 channels, this can be conveniently done by using cascaded 8-to-3 line priority encoders (74LS148) and five lines on a parallel data bus. The arrangement is expandable. It is currently used in an automatized Y-maze for vibrisso-tactile discrimination learning in mice.