Evidence against visual integration across saccadic eye movements

One of the classic problems in perception concerns how we perceive a stable, continuous visual world even though we view it via a temporally discontinuous series of eye movements. Previous investigators have suggested that our perception of a stable visual environment is due to anintegrative visual buffer, a special memory store capable of fusing the visual contents of successive fixations according to their environmental coordinates. In this paper, three experiments are reported that attempted to demonstrate the existence of an integrative visual buffer. The experimental procedure required subjects to mentally fuse two halves of a dot matrix presented in the same spatial region of a display, but separated by an eye movement so that each half was viewed only during one fixation. Thus, subjects had to integrate packets of visual information that had the same environmental coordinates, but different retinal coordinates. No evidence was found in any experiment for the fusion of visual information from successive fixations in memory, leaving the status of the integrative visual buffer in serious doubt.     

Differences in temporal appearance associated with activity in the chromatic and achromatic systems

The temporal appearances of spatially coincident increments that activate the chromatic or achromatic system are different. Whereas near-threshold stimuli that are detected by the chromatic system appear to come on gradually, increments detected by the achromatic system appear to flash or step on. This difference in perception is consistent with previous reports that show differences in the temporal properties of the two systems.     

An Apple II package for computer-assisted telephone interviewing

This paper describes an Apple II (an Apple-compatible) microcomputer package for a computer-assisted telephone interviewing (CATI) system. This system generates random telephone numbers within any number of exchanges that the user supplies, automatically dials the telephone, prompts the interviewer with each question, and records and permanently saves each response. It also provides a printed copy of the collected data by frequency of response in each question category. The Apple II CATI package is readily available, inexpensive, and easy to program in the BASIC language.     

Parameter estimation in latent trait models

Latent trait models for binary responses to a set of test items are considered from the point of view of estimating latent trait parameters=( ₁, , _n ) and item parameters=( ₁, , _k ), where _j may be vector valued. With considered a random sample from a prior distribution with parameter, the estimation of (, ) is studied under the theory of the EM algorithm. An example and computational details are presented for the Rasch model.This work was supported by Contract No. N00014-81-K-0265, Modification No. P00002, from Personnel and Training Research Programs, Psychological Sciences Division, Office of Naval Research. The authors wish to thank an anonymous reviewer for several valuable suggestions.     

Event-related brain potentials to grammatical errors and semantic anomalies

Event-related brain potentials (ERPs) were recorded while subjects silently read several prose passages, presented one word at a time. Semantic anomalies and various grammatical errors had been inserted unpredictably at different serial positions within some of the sentences. The semantically inappropriate words elicited a large N400 component in the ERP, whereas the grammatical errors were associated with smaller and less consistent components that had scalp distributions different from that of the N400. This result adds to the evidence that the N400 wave is more closely related to semantic than to grammatical processing. Additional analyses revealed that different ERP configurations were elicited by open-class (“content”) and closed-class (“function”) words in these prose passages.     

Age and cohort effects on personality factor scores across sexes and racial/ethnic groups

Substantial differences exist across ethnic groups and sexes in generational changes in status among groups residing in Hawaii. Despite these generational differences across groups, age differences in personality are remarkably consistent across sexes and racial/ethnic groups, and the few Sex x Age, Ethnicity x Age or Sex x Ethnicity x Age interactions account for little variance in scores. It is concluded that age/generational differences in personality factor scores in these populations result from age and not, to any major degree, from cohort effects.     

Preparing dichotic tapes using a digital music synthesizer

Digital music synthesizers represent audio signals in the form of binary coded numbers. These binary coded numbers can be manipulated by the operator, thereby altering the audio signal in a variety of ways. The present article describes how these capabilities can be used to produce perfectly aligned dichotic tapes in which the stimulus items are matched on all extraneous (timbre, amplitude, duration) factors.     

Spatial metrics of integral and separable dimensions

Two experiments were conducted to investigate the relationship between dimensional integrality and the form of the combination rule or spatial metric used in a similarity judgment task. In Experiment 1, two groups of eight subjects judged the dissimilarity of all pairwise combinations of 12 rectangles differing in height and width (integral dimensions) or 12 circles differing in size and diameter orientation (separable dimensions). The dimensional organization and spatial metric of both sets of dimensions were determined. The results showed that differences in height and width contributed independently to judgments of the overall dissimilarity of rectangles and that these dimensions were combined using a Euclidean metric. In contrast, substantial interactions between circle size and diameter orientation were found. Combinations of these dimensions also appeared to violate the triangle inequality implying that no spatial metric was appropriate. In Experiment 2, parallelogram size and tilt were similarly analyzed. Although some degree of dimensional interaction was observed, it was found that on the average these dimensions were combined using a city-block metric. In a subsequent speeded classification task, orthogonal interference was observed, which suggested that size and tilt are integral dimensions. The implications of both experiments for the supposed association between the Euclidean metric and dimensional integrality are discussed.