Search

The processing of visual information was investigated in the context of two visual search tasks. The first was a forced-choice task in which one of two alternative letters appeared in a visual display of from one to five letters. The second task included trials on which neither of the two alternatives was present in the display. Search rates were estimated from the slopes of best linear fits to response latencies plotted as a function of the number of items in the visual display. These rates were found to be much slower than those estimated in yes-no search tasks. This result was interpreted as indicating that the processes underlying visual search in yes-no and forced-choice tasks are not the same.

Forced-choice detection was studied in relation to heterogeneity of noise letters and multiple signal letters within tachistoscopic displays. Curves plotting both probability and latency of correct detections vs number of redundant signals at different display sizes exhibit significant interactions with heterogeneity of the noise background, but do not differ as a function of similarity among redundant signals. Application of interactive and independent channels models indicated that noise redundancy operates to a major extent through effects of signal-noise confusability at the decision level, but may also involve perceptual interaction at the level of feature detectors.

Two experiments were conducted to investigate the unsettled question of whether the visual search process is selfterminating or exhaustive. In the experiments three letters were placed on an imaginary circle round the fixation point. Two different letters were used, one of which was defined as the ‘signal’. S s had to respond ‘yes’ when one or more signals were in the display, ‘no’ otherwise. In both experiments the number of signals in the display was varied from 0 to 3. Decreasing latencies with increasing number of signals were observed in both experiments, indicating a selfterminating visual search. In experiment 1 a significant increase in latencies with increasing visual angle was found, in experiment 2 an increase in latency resulting from neighbouring contours. Both factors probably contribute to the slope of the function relating positive responses to display size and to the slope of the function relating negative responses to display size when stimuli are presented in linear arrays as in the experiment by Atkinson et al. (1969). As a result the slopes become more equal, falsely suggesting an exhaustive visual search process.

Two experiments were performed to examine the effect of display size and figure orientation on the horizontal-vertical illusion. According to the visual field hypothesis of Kunnapas (1957a, 1957b) if the relation of the figure components to the surrounding frame is held invariant neither experimental manipulation should exert an appreciable influence. However, both manipulations produced significant effects indicating that the visual field hypothesis is untenable as the primary determinant of the horizontal-vertical illusion. An alternative explanation was discussed.

Two experiments were run to investigate the effects of redundant display items upon response latency in a visual search task. In the first study, Ss searched five-letter displays for a predesignated critical letter. Both critical and noncritical letters could be repeated in the displays. Mean response latency decreased markedly with increasing redundancy in the critical letter and was affected to a lesser extent by redundancy in the noncritical letters. In the second study, Ss were required to detect the presence of redundant letters in displays of from two to five letters, first with no information as to what letter might be repeated, then with knowledge of which letter would be repeated if the display contained a redundant letter. Response latencies in the former case were much slower than in the latter. The implications of these findings for current views of visual information processing were discussed.

An experiment was conducted to determine whether acoustic short-term memory is the factor which limits performance in the tachistoscopic full-report paradigm. Many Es have demonstrated the existence of phonemic encoding in short-term memory. The confusion errors from a tachistoscopic full-report task were, therefore, analyzed for the presence of acoustic confusions. Absolutely no evidence for acoustic confusions was found; visual confusions, however, were abundant. It was concluded that acoustic short-term memory is not the limiting factor in the full-report paradigm.

Visual detection was studied in relation to displays of discrete elements, randomly selected consonant letters, distributed in random subsets of cells of a matrix, the S being required on each trial to indicate only which member of a predesignated pair of critical elements was present in a given display. Experimental variables were number of elements per display and number of redundant critical elements per display. Estimates of the number of elements effectively processed by a S during a 50 ms. exposure increased with display size, but not in the manner that would be expected if the S sampled a fixed proportion of the elements present in a display of given area. Test-retest data indicated substantial correlations over long intervals of time in the particular elements sampled by a S from a particular display. Efficiencies of detection with redundant critical elements were very close to those expected on the hypothesis of constant sample size over trials for any given display size and were relatively invariant with respect to distance between critical elements.

Observers were asked to identify each member of a brief display of geometrie forms. The information content of the displays was manipulated by varying the number of forms displayed and the number of relevant dimensions of each form. The main findings were: (a) Performance was approximately invariant with the number of forms displayed and depended to a minor degree upon the relevant information in each form. (b) Serial-position curves were obtained that had a strong primacy effect, (c) The number of correct identifications per trial was approximately normally distributed, with greater variance than if the forms were independentlyidentified.These findings are discussed in relation to both “coding rate” and “memory capacity” models of immediate visual memory. Neither model accounts for the data. Undetermined organizational factors are suggested to play a role in immediate visual memory. This task appears to depend upon form Identification processes different from those indicated by RT measures.

When a multiletter display is preceded by a bar designating one of the letters for report, reaction time (RT) to voice the indicated letter decreases. Previous research had indicated that the efficiency of this selective mechanism decreases as the number of display elements increases. Two experiments were conducted to determine whether the effect of display size could be eliminated when the indicator precedes the display at long intervals. Results indicated that the display size effect was maintained. The results could not be attributed to eye movements, but were interpreted in terms of a central encoding mechanism that is limited in its precision of localization and exclusion. At the phenomenal level, we can look at an object and see it as an entire object without concentrating on specific details. For example, we may look at the clock on the wall, even noticing what time it is, but not paying "attention" to specific characteristics of the numerals. Or we can phenomenally direct our attention to one of the numerals on the clock such as the 3 and in the process seem to exclude the details of the other numerals. This experience can occur even though our distance from the clock is such that the whole clock face is falling within the fovea and assuring adequate resolution of detail for all parts of the clock. It is as though we had a limited capacity for processing information per unit of time, and we can select which information and in what order it is going to be processed and encoded. We have been employing an experimental analog of this phenomenal experience. Circular displays of a small subset of letters are presented to Ss with a black bar indicator designating one of the letters in the display. The display as a whole is foveal. sub tending approximately 2 deg of visual angle on the diameter. The bar indicator is quite conspicuous, both in terms of its size and shape, but primarily in terms of its location as an extension of an imaginary radius from the center of the display extending beyond the circumference of the imaginary circle along which the letters are arrayed. Ss are instructed to name the designated or target letter as quickly as possible. By manipulating the display variables, we have hoped to delineate some of the characteristics by which selective attention or encoding occurs.

Gas discharge plasma display panels have been under development at Owens-Illinois for several years. This display device offers many advantages including: 1) tube depth (approximately ½ in) essentially independent of display size; 2) random write capability; 3) controlled information storage; 4) selective erase and bulk erase capability; 5) positive registration of displayed information; and 6) rear projection and/or printout capability. Panels, now available (DIGIVUE® display/memory unit), with 33⅓ and 40 electrode lines per inch are appropriate for many applications. However, a somewhat higher resolution of 50 or 60 lines per inch is desired for most general-purpose individual console displays when the number of lines in X or in Y exceeds several hundred. The lower density Owens-Illinois panels are constructed from a parallel plate structure that was selected because of its compatibility with high volume manufacturing processing. This study indicated that the same basic structure could be used at resolutions up to 60 lines per inch. Design dimensions were optimized for this higher resolution and good dynamic operation was obtained. Process techniques were developed to produce panels with 256 by 256 lines and 512 by 512 lines. Several panels of each of these sizes were fabricated and evaluated. The performance of these 60 line per inch panels was comparable to that of the 33 line per inch panels.

For the purpose of measuring masticatory function by means of gravimetric sieveanalysis, it is important to study particle size distribution of masticated materials.The number and size of screens, the number of masticatory strokes, and the quantity of materials have relation to the distribution of particle size, and give different results for measurement. Japanese rice, which is the most suitable test material, was selected, and the effect of these factors were investigated by changing oral conditions, employing 10-, 16-, 32-, 60-, 120-, and 200- mesh screens. Results summarized are as follows :1) Particle size distribution is linear within standard error of 2%, when cumulative percentage oversize is plotted on the probability scale against the screen size on mathematical scale, in the following cases, namely complete dentition, molarsmissing, cases rectorated with crowns and bridges, and some cases of malocclusion, but such cases as full dentures and partial dentures don't give the linear correlation.2) Inclination of this line (coefficient of regression) correlates with the percentage oversize by 10- mesh screen (r=0.9), and equation of regression is characteristic in accordance with oral conditions, therefore percentage oversize of each screen can be calculated from that of 10- mesh screen.3) Particle size distribution is classified into 3 types, -denture-, normal-, and partial edenturous type, according to the coefficient of regression of this equation.4) The correlation between percentage oversize of each screen and the number of masticatory strokes is formularized by y = e-αt within standard error of 3%. “a, ” which iss constant, indicates chewing ability of each subject independent of the number of masticatory strokes (masticatory index) .5) Abovementioned rules are found to be independent of the quantity of test materials from 1 g to 4 g. Masticatory index by the same screen size is inversely proportional to the masticated quantity of rice.6) Masticatory efficiency is calculated by the ratio of masticatory index of each sub-ject to that of standard person, and it seems to be suitable unit to estimate masticating ability.7) Masticatory efficiency by each screen size gives different value according to the type of particle size distribution. By denture type efficiency takes the lowest value at 16-mesh screen, by edenturous type at 10- mesh screen, and by normal type each screen size gives almost equal value.8) The 10- mesh screen is most adequate to detect the rough difference of chewing ability of various oral conditions.

THERE has long been a need for a method of measuring and expressing the size of feed particles. General terms such as “coarse”, “medium” or “fine” are ill-defined at best and subject to variation in usage. References to hammermill screen size are relatively descriptive, but the resulting particle size varies widely because of factors such as hammer speed, extent of wear on hammer and screen, screen area, air flow, method of discharge, kind of grain, moisture content of grain and other variables (Baker and Farrell, 1961; Stevens and Pfost, 1962). A direct measure of the feed particles is obviously more practical than attempting to stabilize the factors that influence the fineness of grind. Two previous measures of feed particle size have been adopted by the American Society of Agricultural Engineers (1961) and the American Society of Animal Science. The method given in this paper is a refinement of the previous…

This paper describes the main features in the design and construction of a CRT display device which is connected to the CDC 3600 computer at the TIFR. The device has capabilities to display texts, graphs and other information automatically. The display size is 10 × 10 in. A light pen is provided which enables a display user to point at a picture part or draw a free-hand sketch on the CRT face. A group of 32 push buttons is also provided which enables a display user to choose an ‘action’ and guide the course of computation from the display console. The device is constructed using discrete components. A total of about 350 printed cards, each with about ten transistors and diodes, is used in the construction of the device. The entire design and fabrication of the logical circuits and CRT electronics was done at the TIFR. The display is in operation for the past two years. The paper concludes by presenting the results obtained and with a short discussion on the ways of interface design in interactive graphica...

Three variables which determine the opportunities for signal-noise confusions, display size (D), number of redundant signals per display (N), and number of alternative signals (A) were studied in relation to nature of the noise elements, confusable or nonconfusable with signals. Data were obtained in a forced-choice visual detection situation, the displays being linear arrays of letters on a CRT screen. For all three performance measures used, frequency of correct detections and correct and error latencies, strong interactions were obtained between all of the other variables and signal-noise confusability. The functions obtained, together with other data bearing on the role of confusions and on spatial relations among characters within the display, suggest a model whose initial phase is a parallel feature extraction process involving inhibitory relations among input channels.

A core-refreshed video display system that can display gray-scale images of 32 intensity levels on a standard monochrome video monitor will be described. The system can also display flicker-free black and white images of more than 800 000 picture elements. There are special features that allow overlaying black and white images on 16-level gray-scale images and manual cursor control via an X-Y tablet. Multiple reduced size images can be accommodated by features that allow independent manipulation of images in separate areas on the display screen. This permits simultaneous display of images before and after processing.

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.”

Visual search was studied under a variety of conditions to clarify some differences among the results of previous investigations and to provide a testing ground for models of visual information processing. Display configuration, target and field composition, exposure duration, and display size (up to 16 elements) were among the parameters investigated. In some conditions, mean reaction time was essentially invariant with display size, while in other conditions it increased substantially and linearly with display size. Current models of visual information processing were evaluated in the light of these and previous findings; all were found wanting. The data seem to demand a system subject to flexible cognitive control processes.

Response times were recorded in a two-alternative, forced choice visual detection situation. Stimulus displays, presented tachistoscopically, were randomly selected consonant letters distributed in random subsets of cells of a matrix. Display sizes in Experiment 1 were 8, 12, and 16 letters; in Experiment 2—1, 4, and 8 letters; on each trial S operated a key to indicate which member of a predesignated pair of letters (signal elements) was present in a given display. Correct response times, on the average, increased uniformly with display size. Incorrect response times were uniformly greater than correct response times and, except for a reduction in the case of one element displays, were constant over display size. These relationships appear to require a modification of one assumption in the earlier proposed serial processing model for tachistoscopic perception.

The promise of producing a cathode-ray-tube type of display with essentially unlimited screen size accounts for much of the current interest in laser displays. The first display that used a laser light source to generate a television image was operated in late 1964. Since that time, a number of experimental laser display systems have been demonstrated, including versions capable of reproducing color television images and displaying computer-generated information. Adequate light modulation and scanning techniques are presently available, but the design of broadly applicable equipment still awaits the development of more efficient multicolor lasers.

Attentional demands were varied in a two-alternative, forced-choice detection experiment. A bar indicator designated the target form in one condition and occurred in random locations in a second condition. Exposure durations necessary for predetermined single-form display HRs were determined for each of eight Ss to measure performance at different levels of perceptual system error. Forms differed in only a single feature. Detection was superior when the bar indicator designated the target form, and differences increased with increased display size. Evidence for interference in detection due to the presence of nontarget forms apart from noting requirements of such forms was found. Estimates of number of perceptual channels noted did not clearly differentiate serial from parallel processing models. It was concluded that display interference error and spatial selectivity influences are important determinants of detection accuracy.

Children of 4, 8, and 14 years performed a visual memory task with easy- or hard-to-label displays and with or without repetition of stimuli over trials. Eight pictures were displayed in serial order, and the task was to find the card in the array that matched an identical probe card. Performance improved with age, and strong serial position effects were obtained for all ages and tasks. In contrast to previous studies, primacy effects were obtained for the youngest children tested. Task difficulty increased with difficulty of labeling and with repetition, but order of task difficulty remained the same for all ages. The d’ measure, borrowed from signal detection theory, revealed differences in criterion levels over serial position, which in earlier studies had been confounded with strength of memory.

A parallel-processing model for scanning is proposed wherein all items in the display set are processed together but with different time constants. The time constant for each item depends upon its serial position and is an additive combination of primacy and recency effects. The primacy effect is linear, and the recency effect is logarithmic. Scanning can either be exhaustive or self-terminating, and “multiple looks” may occur with negative probes. It is shown that this model predicts a linear relationship between reaction time and set size, parallel or 2∶1 slope ratios depending upon the proportion of multiple looks, and serial position effects if the scanning is self-terminating.

This study was conducted for the purpose of exploring relative motion problems in a variety of pilot and navigator tasks. Field studies surveyed methods used by pilots to fly intercepts; analyzed the guidance of air-to-ground missiles; and identified relative motion problems in attitude and navigation displays including the ANIP display. In addition, two experiments were carried out to determine natural responses to inside-out displays as a function of display size, and to determine how to eliminate wrong responses to roll information presented on such displays (reversal errors). The study confirmed the superiority of outside-in displays, made specific recommendations for the design of navigation and attitude displays for air- and spacecraft, and suggested ways of eliminating reversal errors. It also recommended procedures for missile guidance, and provided insights into the cues that pilots use in visual intercepts.

This paper presents several significant design considerations (non-equipment) for computer oriented display systems. It begins with a discussion of display objectives and criteria. Then coding, formats, display request and control, and amounts of information displayed are discussed. Factors related to retinal resolution, display size and detail, group and individual displays and viewing environment are presented. After these miscellaneous considerations, a checklist of primary display characteristics is presented.

Eight adult Ss tachistoscopically viewed letter arrays containing 5, 10, 15, 20, or 25 letters inserted into a 5 by 5 matrix. Each array contained one target letter, either an F or an H. The S’s task was to identify which target letter was present in each display. Within an array, a subset of the letters was typed in red ink, and the remaining subset in black ink. In the cued condition, S was told the color of the target letter; in the uncued condition this information was withheld. The results indicated that color cueing significantly increased the accuracy of letter detection. Also significant were total display size, color of cue, and, within the cued condition, size of the target-color subset.

Display size was varied in a card-guessing game with young children by presenting either 3, 4 or 5 animal cards in serial order, and testing for recall on one of the cards. Marked recency effects were observed at all stages of training, and during the early trials, some primacy was noted. Retrieval appeared to be an all-or-none phenomenon, in contrast to previous studies with 8-item displays, which found generalization and above-chance guessing on the second choice.

A multiconsole computer display system has been designed that provides very rich displays at low unit cost. Each BRAD (Brookhaven RAster Display) console can plot tens of thousands of points, or up to 4000 characters at 30 frames per second. After an initial display system investment of $50,000, each display, with teletype, cost less than $3,000. The technique employed is that of programmatically generating a binary image of the desired display in a computer. The image is written on a rotating drum memory. Independent read heads continuously display the picture, which is generated by swept horizontal lines. A standard TV monitor serves as the display device. The technique has two drawbacks. A computer must compute any image to be displayed. Also, the “pointing” interaction is more difficult. This is because the pointing function gives only the coordinates of the point on the screen. The inverse of the map generation process is required to calculate the coordinates at the input space.

The effect of stimulus set size was studied in a visual search task called “matching-to-sample.” Ss’ task was to locate a predetermined “matching” stimulus in a display of similar stimuli. It was found that increasing the number of different stimuli seen on previous trials, while holding display size constant, increased reaction time (RT) to identical displays. This result is discussed in relation to feature-testing models of stimulus processing.

The main features of domestic monochrome and colour receivers are surveyed, particularly with respect to the larger screen size. Circuit technology has reached the stage at which integrated circuits are starting to challenge the transistor while in certain applications the valve still has a major advantage, mainly due to the scanning power required by the picture tube.