The effect of lateral visual fixation on response latency to verbal and spatial questions

The results of several studies have suggested a relationship between lateral eye movements and contralateral hemispheric activation or ipsilateral inhibition. The present study investigated the effects of lateral and central eye fixation on response latency to verbal and spatial questions. Response latencies for verbal questions were significantly longer when subjects fixated to the left or centrally, as compared to the right. On spatial questions, response latencies were significantly longer in the right fixation condition than in the other conditions. The results indicate that visual fixation ipsilateral to hemispheric activation is related to slower problem solving, and suggest that eye movements during cognitive activity may have functional significance.     

Effect of smooth vs step interval gradients upon interval gap detection

The effect of smooth and step-wise auditory interval gradients upon the discrimination of an interval change, or gap, was studied. Gap discrimination was substantially better with smooth interval gradients than with step gradients when the gap was surrounded by a large number of intervals. This result leads us to ask whether gradiënt phenomena of the Mach-band type are critically dependen t upon the existence of smooth, rather than step, gradients     

The concreteness of attributes in concept learning strategies

Ss were presented with conjunctive concept learning tasks using geometric stimuh in two experiments and using combinations of abstract characteristics in two other experiments. Evidence indicated that the conjunctive hypotheses for geometric stimuli were not mediated by component values but were sampled as unitized wholes. In contrast, conjunctive hypotheses for abstract attributes were sampled via independent combinations of component values. The differential processing was not found to be associated with the variation of stimuli on the verbal-nonverbal dimension.     

Loudness effects in pairs of tone bursts

The loudness of dichotic and monotic pairs of short tone bursts was investigated as a function of the interburst time interval. For short intervals, the loudness was increased relative ty the loudness of a single burst. However, the loudness of a burst pair was equal to the loudness of the second burst in the pair and, therefore, no loudness summation but only a loudness enhancement took place. In dichotic bursts, the loudness enhancement decayed monotonically as the time interval increased, and the rate of decay increased with sound intensity. In monotic bursts, the loudness enhancement decayed to a minimum at about 40 msec, independent of sound intensity. It had a tendency to rebound at longer time intervals and go through a relative maximum in the vicinity of 200 msec. The results are interpreted in terms of an interaction of peripheral and central poststimulatory inhibition with temporal summation.     

Discrimination of restrictions upon sequentially encoded information: Variable length periodicities

Two-state Markov sequences were encoded in the form of auditory pulse trains for forced-choice discrimination tests. Successive items were selected by block sampling from specified patterns, defined either in terms of a “string” with a beginning and an end or in terms of a “circle” without a beginning and end. The discriminability of such sequences is     

Methodological examination of the PEST (parametric estimation by sequential testing) procedure: II

Finite-state Markov sequences were constructed by a small digital computer, translated to interval-coded electrical pulse trains, and converted to sound. An adaptive stimulus programming procedure of variable step size, PEST, was employed to obtain interstate interval thresholds as a function of restrictions upon the internal structure of the sequences. These thresholds are not independent of the exit criterion for the adaptive procedure. An interactive approach is suggested for determining the exit criterion in order to protect the data against arbitrary decisions made by the E.     

Perception of two-dimensional Markov constraints within visual displays

A method is described for constructing visual displays in which statistical constraints are encoded within two spatial dimensions without introducing one-dimensional linear constraints. Within each local group of four elements, the state of one element was determined with a given probability by the previously generated states of the other three. Ss rated such displays on a scale from “lumpy” (or crude texture) to “lacy” (or even texture). The consistency of classification obtained for displays with strong aggregated (“lumpy”) properties was substantially higher than that obtained for displays with strong distributed (“lacy”) properties. An incidental feature of the Ss’ behavior was their deliberate degrading of the visual quality of the displays. Comparison is made with one-dimensional displays concatenated in two dimensions.     

Subjective pictorial information and visual search

The effects of a combination of variables previously studied in ordinary and dichotic immediate memory were examined in bisensory memory, wherein the visual and auditory modalities were employed. These variables. combined in a factorial design. were: (1) type of material; (2) rate of presentation of material; (3) order of recall for a modality. either first or second; (4) locus of instructions about order of report; and (5) overall differences in memory for each modality. The variables of instruction, order of report, and nature of materials yielded effects in the bisensory situation similar to those reported for the dichotic and ordinary immediate memory situations. On the other hand. interference effects due to the combination of materials in the two channels were practically nonexistent. Additionally, when the modalities were stimulated simultaneously each displayed curves predictable from data obtained when it was explored independently of the other modality.