An improved measurement technique for human operator stability in aiming tasks

A technique is presented for field measurement of human operator stability in an aiming task. The small angular displacements of the aiming axis are measured by photographing a part of the target as reflected by a mirror mounted on the aiming device.     

Evidence that fixation digits can contribute to visual field asymmetries in lateralized tachistoscopic tasks

Fixation point digits have been widely used in tachistoscopic laterality studies as a simple and convenient means of ensuring unihemispheric projection of stimulus materials to the hemispheres. Previous findings demonstrate that fixation digits do not influence asymmetries in recognition accuracy studies with adult Ss. Present results, comparing four conditions differing in their use of fixation digits, show that in the naming latency paradigm the requirement to remember and report fixation control digits significantly augments RVF superiority. Implications for other latency tasks are discussed.     

An improved technique for creating hemifacial chimeras

In numerous studies, facial composites of the right and left hemifaces have been used to explore lateral differences in facial expressions. In the majority of these studies, a single technique has been used to create the stimuli: “Wolff’s split half technique,” which was devised at the beginning of the century. Chimeras thus made are weakened by several confounding factors (e.g., hair form, background, shadows), which are unrelated to the original stimuli and consequently may interfere with the examination of subtle facial expressions. This paper offers a modified method using computer graphics that seems to solve such drawbacks.     

Stimulus position functions in tachistoscopic identification tasks: Scanning,rehearsal, and order of report

Three experiments were conducted to investigate the locus of attentional control under the information-overload conditions stemming from tachistoscopic presentation of a horizontally arranged row of letters. In Experiment 1, left-right visual field accuracy differences were greater in a whole- than in a single-report task, reflecting a pronounced influence of report order bias effects. However, accuracy in the single-report task, which is relatively unaffected by report order biases, also declined from left to right across stimulus positions. In Experiment 2, single-report task requirements which provided an opportunity for rehearsal had negligible effects on the shape of the stimulus-position function. In Experiment 3, the leftright accuracy differences were observed to vary as a function of cue delay interval in a single-report visuospatial probe task. The degree of left-field superiority was negligible with a short delay interval, and much greater with longer delay intervals. The results are discussed in terms of a cognitive scanning operation.     

Cross-modal correlation of dichotic and tachistoscopic language laterality tasks: the importance of familial sinistrality

Previous studies have found little if any correlation between dichotic and tachistoscopic language laterality task performance asymmetries. Problems with these studies have been that quite dissimilar auditory and visual tasks have often been used, and the reliability of the asymmetry measures has generally been unknown or, when known, relatively poor. We assessed the cross-modal correlation for two tasks, the Bilateral Object Naming Latency Task (BONLT) and the Dichotic Object Naming Latency Task (DONLT). These tasks are highly similar and have demonstrated high reliabilities. A significant, though rather small, cross-modal correlation was found (r = +.28). When cross-modal correlations were computed for FS- and FS+ subjects separately, no correlation was found for FS+ subjects (r = +.02), but the correlation for FS- subjects was highly significant (r = +.54, p less than .004). This led us to reexamine some previously collected data (P.L. Van Eys and W. F. McKeever, 1988, Brain and Cognition, 4, 413-429) which had administered two highly reliable language laterality tasks (the BONLT and the Dichotic Consonant Vowel Task), but had not assessed cross-modal correlation. A significant cross-modal correlation was found for FS- but not for FS+ subjects. The results are consistent with the hypothesis of H. Hecaen, M. De Agnostini, and A. Monzon-Montes (1981, Brain and Language, 12, 261-284) which suggests that one effect of FS+ is to induce a greater heterogeneity of localizations of different language processes.     

Evidence for independent parallel channels in tachistoscopic perception

This paper reviews the implications of a number of experimental results for a test between two different types of models of perceptual processing: models that assume a limitation of perceptual capacity vs models that postulate independent, parallel perceptual channels. The results of recent “detection” experiments (e.g., Estes & Taylor, 1966) have been consistent with the limited-capacity model developed by Rumelhart (1970). The same results, however, are predicted by the “ICC” independent-parallel-channels model, an extension of work by Eriksen and Spencer (1969) developed in the present paper. This model emphasizes the interaction of two factors: decisional properties of the detection task, plus perceptual confusion phenomena known to occur under tachistoscopic conditions.Two experiments relevant to a test between the ICC and Rumelhart conceptions are reported. Experiment I involved a “time-sharing” paradigm that varied the demands of two detection tasks performed within a single trial. Experiment II involved the elimination of certain perceptual confusion phenomena. The results of Expts I and II appeared consistent with the ICC model but inconsistent with the Rumelhart model. After consideration of alternative limited-capacity models, it was concluded that: (1) a decision-confusion interaction is a necessary component of information-processing models, and that (2) the ICC independent-parallel-channels model is sufficient to account for the broad spectrum of experimental results reviewed.     

Response monitoring and expectancy in random serial RT tasks

Two different sequential patterns have been reported in serial reaction-time (RT) tasks with random stimulus sequences, depending on the response-to-stimulus interval (RSI). When RSI is short a first-order repetition effect and a higher order benefit-only pattern are found, and when RSI is long a cost-benefit pattern is observed. In a series of three experiments, we found that the patterns are not unique for spatial dimensions, and that the benefit-only pattern does not appear for irrelevant stimulus features. The cost-benefit pattern, on the other hand, can shift to irrelevant locations, but not to irrelevant colour. Distributional analyses of the sequential effects demonstrate that the first-order repetition effect can be dissociated from the higher order effects. The results are interpreted as support for the role of response monitoring in the development of the benefit-only pattern at short RSI, while the first-order repetition effect is explained as repetition priming. With a long RSI, the cost-benefit pattern is confirmed as a low-level subjective expectancy process, which is primarily controlled by stimulus location. The data clearly strengthen the support for three different processes generating sequential effects in random serial RT tasks.     

Source dimensions are retrieved independently in multidimensional monitoring tasks

In 3 experiments, the authors determined whether remembering a source dimension created a more complete internal reinstatement of the encoded event and thus cued access to other source dimensions. Results consistently showed that memory for the 2 source dimensions was correlated: correct responses on 1 dimension were typically associated with correct responses on the other. However, externally reinstating 1 source dimension at test had no influence on memory for the other dimension (Experiments 1A and 1B), and the ability to remember a dimension was the same whether it was tested in isolation or immediately following the retrieval of the other dimension (Experiment 2). Thus, there was no evidence of cuing across source dimensions.     

Texture-based tasks are little affected by second tasks requiring peripheral or central attentive fixation.

Experiments are described in which observers attempted to perform concurrently two separate visual tasks. Two types of tasks were used: the identification of a T-shaped or L-shaped letter target, and the detection or localization of a texture element of unique orientation (texture target) within a dense texture. Combining these tasks to form various task pairs, performance as a function of stimulus onset asynchrony (SOA) was established separately for each task in a pair. In addition, performance was measured when each task was carried out by itself. When paired, two identification tasks (T or L) on (two) letter targets required a significantly larger SOA than either identification task by itself. This outcome suggests the involvement of serial performance and competition for a limited resource, confirming that letter identification requires attentive fixation. However, when the identification of a central letter target was paired with the localization (upper or lower hemifield) of an eccentric texture target, performance in the pair was comparable to performance of each task by itself. This suggests parallel performance and a lack of conflict over resources. The outcome was similar when the identification of an eccentric letter target was paired with the detection (present or absent) of an eccentric texture target. These results are consistent with the possibility that localization and detection of a textural singularity do not require attentive fixation.     

Sex in lateralized tachistoscopic word recognition

Although a generalized sex difference in lateralization appears to be established, a review of the literature pertaining to lexical tachistoscopic tasks suggests a dissociation by method: females show reduced visual field asymmetries relative to males in lexical decision and naming, but not in word recognition. Here 14 recognition experiments from the author's laboratory are subjected to meta-analysis, and the literature review is confirmed. There is no sex difference is visual field asymmetry for the task, although an overall field difference is found and statistical power is high to find the interaction. Possible reasons for the discrepancy with lexical decision and naming findings are discussed. One possibility is that stress on reaction time in those tasks produces a complex interaction between sex, activation/arousal, and hemispheric differences, which is not found when a less speeded method is used.     

An improved method for tetrachoricr

From the ratio of the cross-products of a fourfold table, with the application of two tabled corrections, tetrachoricr's can be estimated with a mean discrepancy of less than .005 even when splits vary greatly from the medians. The necessary calculations can be handled by slide rule and the correction tables used without interpolation.     

A tachistoscopic software system for use in remote timesharing applications

A program is described that permits the use of an Imlac PDS-1 display computer, in conjunction with a host timeshare system, as a software-controlled tachistoscope. Alphanumeric and graphic message strings are received from the host computer over a telephone line, and are then displayed for specified periods of time in sequence. The display computer records the S’s responses and reaction time and reports this information back to the host computer for recording and analysis. The system is designed so that the burden of software development for the realization of a specific experimental plan is shifted to the large-capacity host machine, and it can utilize all of the features of standard FORTRAN as implemented on the host computer system.     

Modeling behavioral measures of error detection in choice tasks: response monitoring versus conflict monitoring

The present study investigated the mechanisms underlying error detection in the error signaling response. The authors tested between a response monitoring account and a conflict monitoring account. By implementing each account within the neural network model of N. Yeung, M. M. Botvinick, and J. D. Cohen (2004), they demonstrated that both accounts make different predictions as to how error signaling performance is influenced by varying the participants' response criterion. These predictions were tested in an experiment using the Eriksen-flanker task. The qualitative pattern as well as a model fit favored the response monitoring account, which states that error detection is mediated by detecting internal error corrections.     

An automated identification system for use with computer-controlled tasks

Monkeys of various species can use a joystick to perform a variety of computer-generated tasks. The purpose of this paper is to describe an automated system that determines which subject in a social group has completed a task. The system is based on a microchip that is easily injected into the forearm. The present paper demonstrates the technique with 1 animal that had a different chip in each arm.