A deglitching circuit for the AA50 D/A converter

Switching transients or “glitches” are frequently encountered in signal processing applications involving digital-to-analog (D/A) conversion. A low-cost “deglitching” circuit is described and implemented for the Digital Equipment Corporation AA50 D/A converter option on the PDP-8/e minicomputer. Switching transients were eliminated using a noninverting, unity-gain sample-and-hold circuit (employing Datei System’s SHM-IC-1). Switching transients were reduced to below-noise levels across a wide range of output levels and sampling rates.     

Contour specificity of the McCollough effect

Subjective estimates of McCollough aftereffect strength are significantly reduced when certain spatial features of the line grating patterns are manipulated. Results are dependent upon whether the spatial parameters of the test or inspection patterns are altered. Changing the angular slant, contour sharpness, or contour completeness of the inspection gratings does not affect aftereffect strength, but changing the spatial frequency, contour sharpness, or contour completeness of the test gratings does. The implications of these results are discussed with regard to theories offered to explain the McCollough effect.     

A cognitive-behavioral perspective on intelligence

The present editorial has two purposes. The first purpose is to indicate a parallel trend in two seemingly disparate areas of research which upon closer examination have interesting possible ties. These research areas are information processing and cognitive-behavior modification (CBM). The second purpose is to highlight the role that affect plays in intellectual functioning, noting some of the implications which then follow for the assessment of intelligence.     

Pupillometric assessment of retrieval operations in factual long-term memory

The process involved in recall from long-term memory were studied through the use of a general knowledge questionnaire and the technique of pupillometry. Degree of processing of the components of the retrieval process was inferred from second-by-second monitoring of pupil size. Measurements were recorded during subjects' attempts to retrieve the answer to the query, or if unsuccessful, from clues of the target (first and last letters), and if still unsuccessful, to recognize the presented target word as being associated with the question (the “Of course”, or “That's it!” experience). Pupil size differed according to the nature of the three task demands. Additionally, there were differences based on the type of outcome within the question trial (e.g., between target known but blocked — feeling-of-knowing/tip-of-tongue — and target not known), and the answer trial (recognize vs not recognize the question—answer relationship). The results were related to the search and decisional processes of retrieval.     

Conversion of a printing calculator to an inexpensive printing counter

A procedure is described for simple conversion of a printing calculator to an inexpensive printing counter. The unit is particularly useful for unattended data collection. A timing circuit controls printout of accumulated data at specified time intervals.     

Televised classroom events as distractors for reading-disabled children

Three experiments examined the influence of videotaped classroom events on the academic performance and study behavior of reading-disabled and normally reading children in grades 1 through 6. In experiments 1 and 2a an experimenter-controlled presentation of these distractors resulted in performance decrements, the magnitude of which was greater for higher difficulty tasks. The distractor effects were similar for the two groups in this condition. However, when the children themselves were allowed to control their degree of exposure to the same distractors in experiment 2b, the reading-disabled children were less likely to act to escape the distraction. Results are discussed in terms of children's metacognitive awareness of distraction, and implications for the classroom are considered.