Reducing the effects of adjacent distractors by narrowing attention.

Three experiments explored the gradual narrowing of visual attention to a letter target when other letters were positioned close by. The method by which attention was narrowed involved presenting a digit target immediately prior to the latter target and in the same location for progressively shorter durations and requiring the subject to identify both the digit target and the letter target before responding. The response time data from the first 2 experiments indicated that shorter durations of the digit reduced the amount of information processed from noise letters positioned on either side of the letter target. In the third experiment, in which separation of letters was increased slightly, the response times indicated that the information from flanking noise letters may have been virtually eliminated.     

Rater information acquisition processes: Tracing the effects of prior knowledge, performance level, search constraint, and memory demand

Research on performance ratings has tended to neglect factors affecting raters' acquisition of ratee performance information. The present research examined the dynamic effects of this rater information acquisition process. Study 1 examined the effects of prior ratee knowledge (familiarity) and ratee performance level on subsequent acquisition of ratee performance information under varying levels of constraint. After exposure to prior ratee information, raters acquired additional information concerning a set of ratees using a computer controlled information board procedure. The results indicated significant effects on the amount of search for prior knowledge, search constraint, and the interaction between prior knowledge and performance level. Study 2 extended the research by including a memory component (time delay) between the exposure to prior information and subsequent search. Results were congruent with Study 1. They indicated significant main effects on the amount of search for prior knowledge, ratee performance level, search constraint, and on the interaction between prior knowledge and performance level. In addition, the results indicated a significant interaction between memory demand and prior knowledge. Implications of these results, limitations, and extensions of this research approach are discussed.     

Microsecond resolution timing with Sun workstations

A high-resolution clock is often indispensable for the accurate measurement of millisecond or microsecond resolution intervals, and it is impossible to measure the probability distribution of short intervals without one. This paper describes a microsecond clock for Sun 3 and 4 workstations that we designed, built, and have made publicly available. It also explains how to measure intervals shorter than a computer’s clock resolution, and derives confidence intervals for such measurements.     

Back to basics: Percentage agreement measures are adequate, but there are easier ways

Percentage agreement measures of interobserver agreement or "reliability" have traditionally been used to summarize observer agreement from studies using interval recording, time-sampling, and trial-scoring data collection procedures. Recent articles disagree on whether to continue using these percentage agreement measures, and on which ones to use, and what to do about chance agreements if their use is continued. Much of the disagreement derives from the need to be reasonably certain we do not accept as evidence of true interobserver agreement those agreement levels which are substantially probable as a result of chance observer agreement. The various percentage agreement measures are shown to be adequate to this task, but easier ways are discussed. Tables are given to permit checking to see if obtained disagreements are unlikely due to chance. Particularly important is the discovery of a simple rule that, when met, makes the tables unnecessary. If reliability checks using 50 or more observation occasions produce 10% or fewer disagreements, for behavior rates from 10% through 90%, the agreement achieved is quite improbably the result of chance agreement.     

Conceptual preference for thematic or taxonomic relations: A nonmonotonic age trend from preschool to old age

Two experiments examined the development of conceptual preference for either thematic (functional) or taxonomic relationships in a match-to sample task. In Experiment 1 twenty subjects from each of five age groups—preschool to old age—completed a method of triads preference test where they were forced to choose a thematic or taxonomic match. Young and old individuals preferred the thematic parings while school age and college adults preferred the taxonomic matches. Although the Age × Preference relation was pronounced, the majority of subjects at all ages could provide adequate justification of both the preferred and nonpreferred relationship. In addition, kindergarten subjects in Experiment 2 could readily be trained to respond on the basis of the nonpreferred mode. These data suggest that the pervasive shift in conceptual responding from syntagmatic to paradigmatic, thematic to taxonomic, etc., represents a change in preference rather than a shift to a fundamentally new way of organizing knowledge.     

Real-time clocks for microcomputers in behavioral research

Real-time clock strategies are described for microcomputers in behavioral research. Software-oriented and hardware-oriented counters are described in both free-running and strobed modes. An example of a clock using the Intel 8253 is given, along with driving software in 8080 assembly code and hardware for the S-100 bus.     

Apparatus for collecting voice chronography data

The conversion of speech into on-off pulse patteras representing talk spurts and pauses is a major tool used by psychologists in analyzing interactive communications behavior. We describe a conversion method and a means for interfacing its output with a computer, which allows the collection of large amounts of speech data from one or more sources. The major improvement over prior art is the ability to reject cross talk between neighbor speakers while permitting the detection of simultaneous speech. In the evaluation of the performance of the apparatus, no errors were detected for single-party speaking. Infrequent small errors occurred in the detection and duration of talk spurts and pauses during two- and three-party speaking, but these would probably be acceptable in most applications.