The role of phonological activation in the visual semantic retrieval of Chinese characters

The Stroop paradigm was used to examine the role of phonological activation in semantic access and its development in reading Chinese characters. Subjects (age 7-23 years) of different reading ability were asked to name the display color of Chinese characters. The characters were displayed in four different colors: red, yellow, blue and green. There were five types of relationships between a character and its display color: semantically congruent, phonologically congruent, semantically incongruent, phonologically incongruent and neutral. In addition to the classical Stroop effects, interference and facilitation effects from the homophones of color characters were also observed. The younger children and those with lower reading ability exhibited stronger Stroop effects. These findings suggest that phonological codes are activated automatically in Chinese character recognition. Furthermore, there is more phonological activation in the semantic retrieval of children in lower grades and those with lower reading ability.     

Computer programming for generating visual stimuli

Critical to vision research is the generation of visual displays with precise control over stimulus metrics. Generating stimuli often requires adapting commercial software or developing specialized software for specific research applications. In order to facilitate this process, we give here an overview that allows nonexpert users to generate and customize stimuli for vision research. We first give a review of relevant hardware and software considerations, to allow the selection of display hardware, operating system, programming language, and graphics packages most appropriate for specific research applications. We then describe the framework of a generic computer program that can be adapted for use with a broad range of experimental applications. Stimuli are generated in the context of trial events, allowing the display of text messages, the monitoring of subject responses and reaction times, and the inclusion of contingency algorithms. This approach allows direct control and management of computer-generated visual stimuli while utilizing the full capabilities of modern hardware and software systems. The flowchart and source code for the stimulus-generating program may be downloaded from www.psychonomic.org/archive.     

The shape of inhibitory fields in the human visual system

Five point sources of light were displayed sequentially in a horizontal line, with .45 in. of separation between each point, employing a computer-based cathode-ray tube display system. If a particular display order and appropriate display rate is employed, then the first two points being displayed will not be perceived. By systematically varying the spatial location of these two blanked points relative to the three unblanked points, a start is made towards mapping the shape of visual inhibitory fields in man, and this general technique is related to the work of Hartline and of Ratliff on lateral inhibition and to that of Hubel and Wiesel with receptive fields in the cat and monkey striate cortex.     

An intelligent experimental station controller for human experimental psychology

The purpose of this paper is to describe the intelligent experimental station controller used in the extensible multiprogramming system for experimental psychology (EMPP) at the University of Washington. The EMPP system is an integrated hardware and software system designed to simplify the development of on-line psychological experiments. An intelligent graphics control system is one of the most important aspects of the system. The controller oversees the operation of eight independent experimental stations, each containing a cathode ray tube (CRT) terminal and a keyboard console. In addition to conventional computer interface functions, the controller contains an extensible hardware character generator which allows dynamic selection of the display character set. This paper describes both the hardware and software features of the system.     

Selecting spatial frames of reference for visual target localization

This study examined the selection of spatial frames of reference for target localization in visual search. Participants searched for local target characters in global character configurations. The local targets could be localized relative to the character configuration in which they were embedded or relative to the presentation screen on which the configurations were displayed. We investigated under which conditions the configurations, or the screen served as frame of reference for target localization. Three experiments revealed an increasing impact of screen-related target localization with decreasing spatial uncertainty of targets in screen-related coordinates. The results indicate the capability of the visual system to localize relevant visual stimuli with respect to those frames of reference that yield the most redundant spatial distribution of these stimuli.     

Familiarity, redundancy, and the spatial control of visual attention

Highly familiar letter sequences (English words) in noncued portions of a tachistoscopic display were shown to substantially reduce accuracy of partial report. These findings suggest that in addition to facilitating character scanning, familiarity may operate in automatically directing attentional resources to a particular spatial region of a display. Such attentional capture may be disruptive if the material to be reported is presented at another location.     

Letter string processing and visual short-term memory

The present study investigated whether expertise with letter string processing influences visual short-term memory capacity. Specifically, we examined whether performance in a change-detection task would vary as a function of stimulus type (letters vs. symbols) and type of display (horizontal, vertical, and circular). Participants were asked to detect a one-character change in a briefly presented character array following a delay of 900?ms. Concurrent articulation was used to limit effects of rehearsal. Type of display significantly affected performance with letters, but not with symbols, with a selective increase in change-detection accuracy for horizontally presented letter arrays compared with vertical and circular arrays. These findings confirm the standard limits of storage in visual short-term memory, but critically reveal a selective advantage for letter arrays over symbol arrays when presented horizontally. Such an advantage is probably due to the utilization of a specialized encoding mechanism built up over years of reading experience.     

The impact of ordinate scaling on the visual analysis of single-case data

Visual analysis is the primary method for detecting the presence of treatment effects in graphically displayed single-case data and it is often referred to as the “gold standard.” Although researchers have developed standards for the application of visual analysis (e.g., Horner et al., 2005), over- and underestimation of effect size magnitude is not uncommon among analysts. Several characteristics have been identified as potential contributors to these errors; however, researchers have largely focused on characteristics of the data itself (e.g., autocorrelation), paying less attention to characteristics of the graphic display which are largely in control of the analyst (e.g., ordinate scaling). The current study investigated the impact that differences in ordinate scaling, a graphic display characteristic, had on experts' accuracy in judgments regarding the magnitude of effect present in single-case percentage data. 32 participants were asked to evaluate eight ABAB data sets (2 each presenting null, small, moderate, and large effects) along with three iterations of each (32 graphs in total) in which only the ordinate scale was manipulated. Results suggest that raters are less accurate in their detection of treatment effects as the ordinate scale is constricted. Additionally, raters were more likely to overestimate the size of a treatment effect when the ordinate scale was constricted.     

How to obtain near-millisecond precision on the IBM PC with visual stimuli not exceeding one printed line

Techniques are described for using an IBM PC equipped with a mouse to investigate the reading of character sequences of maximally one display line. Solutions are given to problems that arise and derive from the PC’s real-time clock, the slowness of the display, and registration of input during a test session. A program for using the techniques to study asynchronous perception of printed words is described, and a demonstration program is provided as an appendix.     

Evaluation of tablet computers for visual function assessment

Recent advances in technology and the increased use of tablet computers for mobile health applications such as vision testing necessitate an understanding of the behavior of the displays of such devices, to facilitate the reproduction of existing or the development of new vision assessment tests. The purpose of this study was to investigate the physical characteristics of one model of tablet computer (iPad mini Retina display) with regard to display consistency across a set of devices (15) and their potential application as clinical vision assessment tools. Once the tablet computer was switched on, it required about 13 min to reach luminance stability, while chromaticity remained constant. The luminance output of the device remained stable until a battery level of 5%. Luminance varied from center to peripheral locations of the display and with viewing angle, whereas the chromaticity did not vary. A minimal (1%) variation in luminance was observed due to temperature, and once again chromaticity remained constant. Also, these devices showed good temporal stability of luminance and chromaticity. All 15 tablet computers showed gamma functions approximating the standard gamma (2.20) and showed similar color gamut sizes, except for the blue primary, which displayed minimal variations. The physical characteristics across the 15 devices were similar and are known, thereby facilitating the use of this model of tablet computer as visual stimulus displays.     

A conceptual category effect in visual search: O as letter or as digit

Evidence is presented for a processing mechanism in visual recognition that depends upon how the stimulus array is conceptually categorized rather than upon its physical characteristics. Ss had to detect a letter or digit target in a field of letters or digits. When target and field were of the same category, reaction time increased with display size. When target and field category differed, reaction times were independent of display size. This category effect held even for the ambiguous target character 0 that yielded reaction time functions appropriate to how it was specified prior to presentation: as “zero” or as “ō.”     

Conditional control in visual selection

Attention and eye movements provide a window into the selective processing of visual information. Evidence suggests that selection is influenced by various factors and is not always under the strategic control of the observer. The aims of this tutorial review are to give a brief introduction to eye movements and attention and to outline the conditions that help determine control. Evidence suggests that the ability to establish control depends on the complexity of the display as well as the point in time at which selection occurs. Stimulus-driven selection is more probable in simple displays than in complex natural scenes, but it critically depends on the timing of the response: Salience determines selection only when responses are triggered quickly following display presentation, and plays no role in longer-latency responses. The time course of selection is also important for the relationship between attention and eye movements. Specifically, attention and eye movements appear to act independently when oculomotor selection is quick, whereas attentional processes are able to influence oculomotor control when saccades are triggered only later in time. This relationship may also be modulated by whether the eye movement is controlled in a voluntary or an involuntary manner. To conclude, we present evidence that shows that visual control is limited in flexibility and that the mechanisms of selection are constrained by context and time. The outcome of visual selection changes with the situational context, and knowing the constraints of control is necessary to understanding when and how visual selection is truly controlled by the observer.     

Some characteristics of visual whole report behavior

A whole report experiment is reported that obtained joint serial position accuracy data, with probability-correct curves as functions of stimulus duration. A second experimental phase compared a condition in which the left part of the linear display was shielded from view during the last part of the stimulus exposure, with a condition in which the right part of the display was shielded from view during the early portion of the stimulus exposure interval, and with a control condition in which no shield was used. A noisy mask came on with the termination of the letter display, in both phases. The bounded performance model, possessing the characteristics of parallelness, independence and limited capacity, was in good accord with the data and fit better than the multicomponent model.     

Detection of one-, two-, and three-dimensional Markov constraints in visual displays II: Multistate displays.

The study of the depth of visual information processing is here extended to multistate displays. Two classes of variables are distinguished: display variables which may either be fixed at a single level or varied over its possible levels, e.g., a numeric character, its brightness, and its orientation; and spatial-temporal variables which assume all possible states within each display, e.g., the x- and y-coordinates of the display, and the time-coordinate, t, representing successive frames of the display. Information was encoded in terms of constraints upon combinations of variables. Excellent discrimination is achieved for detecting constraints among two, but not three, display variables; or for detecting constraints among one, but not two, display variables and up to three spatial-temporal variables. Comparisons are made with previous tests of the depth of visual information processing with binary-coded materials within the spatial-temporal microstructure of the display.     

Software tools for creating line drawings on a CRT

A software package that can be used for the generation of line drawings on CRTs is discussed. The pictures obtained are stored as sets of coordinates of line segments. Complex pictures consist of sets of subpictures. In this way, pictures, or parts of pictures, can be easily manipulated (e.g., rotated, translated, scaled) and can be displayed on different types of display systems.     

Contrast as seen in visual search reaction times.

Three pigeons searched arrays of alphabetic letters displayed on computer monitors. On each trial, either an A or an E appeared, and the reaction time and accuracy with which the bird pecked at this target were measured. In each block of trials, each target (A or E) was displayed alone, or together with a number of distractor letters (2 or 18) that varied in their similarity to the target. During a baseline series of sessions, responses to the A and to the E each yielded food reinforcement on 10% of the trials. In the next series of sessions, reinforcement continued at 10% for A, but rose to 30% for E. In a final series, these reinforcement conditions were reversed. As expected, reaction times increased with target-distractor similarity and (for similar distractors) with the number of distractors. Increased reinforcement of E had no effect on reaction times to E, but produced a very consistent increase in reaction times to A; the average increase was constant across the various display conditions. Reversal of the differential reinforcement conditions reversed this contrast effect. Analysis of the reaction time distributions indicated that increased reinforcement to E decreased the momentary probability of response to A by a constant amount, regardless of display conditions. These results are discussed in relation to theories of contrast, memory, and of the search image.     

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.     

A new approach to the generation of visual stimuli for eye-movement research

An interactive, computer-controlled, visual stimulus generator is described, suitable for both psychophysical and neurophysiological experimentation on human subjects. The system core is a wide-screen electrostatic cathode-ray tube, which can be used both as a television monitor, to display standard video pictures, and as anx-y oscilloscope, so that a bright dot can be moved around the display by electrical signals. In addition, a third working mode is provided, according to which a time-compressed video picture of limited size (fast picture) plays the role that is typical of the spot in a standard oscilloscope. Through computer-assisted time compression, the frame period of the video signal is reduced to about one tenth of its standard value. The fast picture can accordingly be driven by even the fastest eye movements, and it can be displayed as a stabilized image, or, more generally, in the altered retinal feedback condition. Moreover, as compared with a standard video picture, the fast image can be “flashed” over much shorter time periods. Since a standard input video signal is used for both standard and fast video pictures, all the image processing facilities of commercial videographic systems can be fully exploited by the proposed device.     

EMDISP: A visual display system with digital and analogue sampling

EMDISP provides general-purpose assembly language routines that can be called from higher level languages to produce specific application programs for experiments involving visual displays, manual responses, and analogue sampling (e.g., eye movement recording). The display system assumes the use of fast-phosphor oscilloscopes driven by 12-bit digital-to-analogue converters (DACs) to produce point-by-point displays. Within these limitations, EMDISP offers a flexible and efficient method of generating displays, in which elements of a complex display are defined as separate “pictures” and are controlled independently. High-level control of digital and analogue sampling are provided, enabling interactions between the contents of the display and analogue and digital inputs.