Retrieval plus scanning: Does it occur?

In the two experiments reported here, we tested the retrieval-plus-scan model of delayed probe recognition by adding a second probe 2 sec after subjects had responded to the first probe. According to this model, the list items should still be in consciousness from the first probe at the time of the second probe. Consequently, on tests in which the first probe had been tested immediately, we expected to find the same pattern of performance on both first and second probes. On tests in which the first probe came after a filled delay, we expected the first-probe data to show the effects of retrieval and proactive interference. These effects should not be present on the second probe. The results of the first-probe data in both experiments were consistent with the retrieval-plus-scan model. The second-probe data did not fit the model, however. In the first experiment, the second probe on what had been delayed first-probe trials still produced intercept differences, indicating the presence of retrieval. In the second experiment, the effects of proactive interference were still present on the second probe. It is suggested that these results not only invalidate the retrieval-plus-scan model for delayed probe recognition but that they, along with other results, cast doubt on a scanning operation in immediate probe recognition.     

Altering memory through recall: The effects of cue-guided retrieval processing

Three experiments were designed to investigate the influence of initial recall on memory by assessing delayed recall after different immediate cued-recall tests. In all experiments, subjects performed semantic and phonemic encoding tasks on a word list. The subjects then received a cued-recall test that cued the target using the same word as the context word in the encoding task, a test that cued the target with a word from the same level at which the target was encoded, a test that cued the target with a cue from a different level at which the target was encoded, or no immediate-recall test. One day later, the subjects performed a final cued-recall test in which the type of cue (semantic or phonemic) was varied. Consistently, delayed recall was facilitated primarily when the cue on the immediate test was from the same level as the cue on the delayed test. This pattern of facilitation suggests that immediate cued-recall produces an elaboration of an existing memory representation that is closely tied to the type of cue used on the immediate test.     

Evoked potentials and the study of sentence comprehension

Evoked brain potentials were used to monitor moment-by-moment decisions during language comprehension. Subjects read sentences containing temporary syntactic ambiguities for which one of the possible interpretations was semantically implausible. The N400 component of the evoked potential, which is sensitive to implausibility, was used to discover when during a sentence subjects made a decision about the ambiguity. The results demonstrate that readers try to interpret a syntactic ambiguity early in a sentence rather than waiting for disambiguating information. This introduces a new way to use brain activity to study sentence comprehension processes.     

The relationship between variability of intertap intervals and interval duration

Summary Subjects tracked intervals in a synchronization paradigm at interval durations of 180, 210, 240, 270, 300, 400, 500, 600, 700, 800, 900, and 1,000 ms. The variability of intertap intervals (ITIs) shows a sudden increase near 300 ms. This increase is interpreted as indicating the transition from automatic to controlled movement. It is suggested that the sudden change in the variability of ITIs does not reflect the operation of different timing mechanisms at short and long intervals, but differences in the way in which attentional processes come to bear on movement initiation for different interval durations. In contrast to previous findings reported in the literature, a U-shaped function between interval duration and variability in the 300-to-1,000-ms range was not observed.     

Forecasting the impact of the federal sentencing guidelines

The Sentencing Reform Act of 1984, which created the U.S. Sentencing Commission, required that the commisson consider prison capacity in drafting sentencing guidelines. As part of the commission's efforts to meet this requirement, we developed a computer simulation capable of projecting the impact of the commission's guidelines on future sentences and prison populations. According to our projections, “straight” probation sentences will be reduced significantly under the guidelines. However, reducing the use of probation will generate only modest demands on the prisons, and then mostly for community corrections phased in over the course of 5 years. We also project that, while average time served for violent offenses will increase substantially, average time served for most property crimes will remain largely the same. Finally, while we forecast that federal prison populations will grow markedly by the end of this century, this is more a result of the Anti-Drug Abuse Act of 1986 and the career offender provision of the Comprehensive Crime Control Act of 1984 than a result of the guidelines.     

TIMEX2: A modified C-language timer for PC AT class machines

Emerson (1988) provided a simple C-language timing routine for use with PC AT class machines. Unfortunately, this version of the timing routine makes use of nonstandard functions that are not available in all C-language packages. A modified version of this timing routine that does not make use of one of these nonstandard functions is provided. This version of TIMEX runs under the widely available Microsoft C 5.1. The need and availability of the remaining four nonstandard C functions is discussed. Constants needed to convert the timing routine units into seconds and milliseconds are also provided.     

Statistical analysis of fuzzy-set data from neuronal networks

In this study, we describe the process of transforming neuron polarization values that meet the assumptions of ratio data into ordinal data. This is a crisp-to-fuzzy set transformation. A computerized simulation of the application of this process is discussed and nonparametric methods of analyzing fuzzy-set data are presented.     

Programs for visual psychophysics on the Amiga: A tutorial

A typical psychophysical experiment presents a sequence of visual stimuli to an observer and collects and stores the responses for later analysis. Although computers can speed up this process, paint programs that allow one to prepare visual stimuli without programming cannot read responses from the mouse or keyboard, whereas BASIC and other programming languages that allow one to collect and store observer’s responses unfortunately cannot handle prepainted pictures. A new programming language called The Director provides the best of both worlds. Its BASIC-like commands can manipulate prepainted pictures, read responses made with the mouse and keyboard, and save these on disk for later analysis. A dozen sample programs are provided.