An inexpensive real-time microcomputer-based cognitive laboratory system

A computer system, based on the Radio Shack Color Computer, for running experiments in cognitive psychology is described. The system was designed according to the following principles: first, all of the equipment should consist of inexpensive, off-the-shelf components; second, the language used to implement experiments should have real-time commands embedded within the character strings to be displayed, and these real-time commands should be interpreted at run time; third, the system should serve multiple subjects, yet one host should be able to run display terminals for several subjects on independent experiments; and fourth, the system should be able to interface to other display devices and other response-recording devices. Two examples of other devices are discussed: an oscilloscope for rapid visual display and an Apple Macintosh for display of pictures.     

Amiga 1000 hardware timing and reaction-time key interfacing

A method of hardware reaction timing with millisecond accuracy, using one of the Amiga’s CIA 8520 chips, is described. The registers of this chip can be set to enable cascaded timing that functions independently of the CPU and, thereby, avoids the problems of software timing in a multitasking environment. In addition, the interfacing of a pair of reaction-time keys to one of the Amiga’s game controller connectors and a program for polling this port for keypresses are described.     

Decision factors affecting line orientation judgments in the method of single stimuli

Just noticeable differences in orientation are smaller at principal standard orientations than at oblique standard orientations when they are measured with the method of single stimuli. We determined whether this oblique effect is due to an anisotropy in decision factors. A first series of experiments showed that the subjects compare the stimulus with an internal criterion, and that this decision rule is used at all standard orientations. A second series of experiments determined the influence on the oblique effect of nonsensorial variables related to criterion setting. The results strongly suggest that the effect is not due to a criterial noise anisotropy and that criterion-setting processes are similar at principal and oblique standard orientations. The latter conclusion was also supported by an analysis of the sequential stimulus and response dependencies in this task. Hence, it appears that the oblique effect in line orientation discrimination, when it is measured with the method of single stimuli, is due not to decision factors but to a sensorially based anisotropy.     

Some evidence for correlated separate activation in a simple letter-detection task

This study investigates the separate activation versus coactivation issue for redundant targets in a simple letter-detection paradigm with latency as the dependent variable. The results of a one-response visual-search task are reported. Since, on single-target trials, only the target was presented and no accompanying noise element, no “distraction decrement” caused by irrelevant noise elements (Grice et al., 1984) was to be expected. The data obtained showed a clear redundantsignal effect. Subsequent detailed analysis of the latency data using Miller’s (1982) procedure indicated that the results were consistent with a separate activation model and failed to provide convincing evidence in favor of coactivation models. A further analysis of the data indicated that, in the present study, the separate channels were negatively correlated for a range of fast RTs and positively correlated for intermediate and larger RTs. No evidence in favor of Grice et al.’s (1984) distraction-decrement hypothesis was found. The conclusions of this study are that (1) a separate activation model summarizes the essential features of information processing in this simple visual search task, and (2) no convincing evidence in favor of coactivation in visual search tasks has been reported in the literature up to now.     

The University Of Colorado Meaning Norms

There exist surprisingly few normative lists of word meanings even though homographs—words having single spellings but two or more distinct meanings—are useful in studying memory and language. The meaning norms that are available all have one or more weaknesses, including: (1) the collection of free associates rather than meanings as responses to the stimulus words; (2) the collection of single rather than multiple responses to the stimulus words; (3) the inclusion of only the two most frequently occurring meaning categories, rather than all meaning categories, for the stimulus words; (4) omission of the responses typical of each meaning category; (5) inadequate randomization of the presentation order of the stimulus words; and (6) unpaced presentation of the stimulus words. We have compiled meaning norms for 90 common English words of low, medium, and high concreteness using a methodology designed to correct these weaknesses. Analysis showed that words of medium concreteness have significantly more first-response meanings than do words of either low or high concreteness, lending support to the view that concreteness is a categorical, rather than a continuous, semantic attribute.     

Memory cueing and instructional effects on Wason’s selection task

The present study examined the hypothesis that violation and role-playing instructions are necessary conditions for facilitation on Wason’s selection task and that facilitation due to memory cueing via thematic content is secondary. The results of a factorial experiment employing these factors did not support the hypothesis. Memory cueing was indicated as the primary factor, but violation instructions did increase the amount of facilitation observed. This interactive effect and the nature of facilitation by memory cueing are briefly discussed.     

Frames of reference in preschoolers’ perception of motion

Experiments 1 and 2 established children’s (mean age 3 years, 7 months) subject-relative and object-relative motion thresholds at 1°31.37′/sec and 1°9.33′/sec, respectively, speeds well above those found for adults. Experiment 3 established that preschoolers, like adults, attribute object-relative motion to the smaller of two objects, with the inducing properties of the larger stimulus greatest when it is surrounding rather than adjacent to a smaller stimulus. The inducing advantage of surroundedness was equivalent for a single-element square frame and a multielement six-dot frame.