Trace resistance and the decay of long-term memory

A theory of storage in long-term memory is described which characterizes the trace by two properties: strength and resistance. The theory makes four assumptions: (a) The rate of decay of strength equals the force on the trace divided by the resistance. (b) Force is proportional to trace strength and to the similarity of current traces to the previously established trace. (c) Resistance increases as the square root of trace age. (d) The resistance of a trace transfers completely to subsequent increments. The theory accounts for long-term retention functions over delays from 1 min to 2 yr, long retrograde amnesia, unlearning, effects of multiple learning trials and spacing of practice, and possibly recency judgments and retention functions following relearning.     

The overtraining reversal effect in rats: A function of task difficulty

Two experiments were conducted with rats. The first study showed that in the T-maze a brightness discrimination learning problem was more difficult than a spatial learning problem, but in a Ross-maze a brightness problem was less difficult than a spatial task. T-maze brightness and Ross-maze spatial tasks were found to be of equal difficulty.

In the second experiment rats were trained either on a brightness or spatial discrimination reversal problem in the Ross-maze. It was found that overtraining facilitated reversal performance in the spatial task but not in the brightness problem. The theoretical implications of these results were discussed.     

Pause adjustment mechanism and measurement system (PAMMS)

A system is described whereby silent interval duration may be studied as a parameter in the perception of speech pauses under controlled conditions. PAMMS (pause adjustment mechanism and measurement system) provides the S (or the E) with the unique capability of directly manipulating a pause which is then automatically measured electronically. The system includes electronic devices which provide for a specialized switching and dubbing procedure by means of which test tapes are generated.     

Dual trace theory and the consolidation of long-term memory

Retention functions were determined for four Ss for recognition memory of letters at 14 different delays from 3 sec to 5 min and two levels of storage load (1 and 6 letter lists), the retention interval being filled with backward counting. Memory strength retention functions were fit extremely well by assuming that two traces, short-term memory and long-term memory, are operative in this type of memory task. Only the short-term memory trace appears to be present during the first 8 or 10 sec of the retention interval, and this short-term trace decays exponentially with a time constant in the vicinity of 10 sec. Long-term memory is subject to a consolidation process which does not begin until about 10 sec after the study period and which is substantially complete at about 30 sec after the study period. Storage load has a very large effect on the degree of acquisition (learning) for both short and long-term traces, but storage load appears to have only a moderate effect or no effect on the decay rate of the short-term trace. There is some suggestion that the duration of the consolidation phase is shortened by an increase in storage load.     

Optical insignificance of the nose and the pinocchio effect in free-scan visual straight-ahead judgments

We tested whether the retinal projection of the nose was used to reduce error in free-scan judgments of straight-ahead. Subjects set a luminous target straight ahead with no restrictions on eye position. On half the trials, the nose was visible; on the other half, it was not. Nose visibility did not reduce absolute error. To check response measure sensitivity, an external reference condition was added. The two nose conditions were run with no external surrogate reference, or with a reference on the nose, 3/8 of the way between the target and the observer, or directly in front of the target, which was 183 cm from the observer. There was no advantage of a reference on the nose as compared to no reference, and nose visibility did not interact with the surrogate reference conditiori. However, the external reference became much more effective in reducing absolute error as it approached the target. We called this the Pinocchio effect. It is consistent with the adjacency principle, but its cause is not certain. Most importantly, the Pinocchio effect showed that the null nose result was not simply a matter of an insensitive response measure.     

Can “words” be processed as integrated units?

Three experiments examined the information processing of letters embedded within one-syllable words and similar unpronounceable sequences. A speeded discrimination task was used to detect processing differences between words and nonwords in a situation where both the identity and position of critical display information was known to subjects before stimulus presentation. Results indicated that word pairs differing by two letters were more quickly discriminated than two words differing in a single letter, while nonword pairs differing in two letters were discriminated no faster than two nonwords differing in a single letter. A further comparison showed a performance advantage for words over nonwords in a condensation task that forced a scan of stimulus letters for correct responding. These results suggest that familiarity affects information processing at a perceptual level, and are incompatible with theories suggesting that familiarity effects are due to inferential factors following letter feature analysis.     

An experiment control computer system time shared by several laboratories

An experiment control computer system, operational for more than 2 years, is discussed. The system is multiprogammed, using a vendor supplied real-time operating system. Individual experiments employ multitasking—fast response functions are implemented in core resident tasks while interactive and other slow response functions are implemented in tasks that operate under time sharing. The areas of psychological research currently supported are concept formation studies, EEG evoked response studies, monitoring the autonomic nervous system, perception studies, and family interaction studies.