Language habits and detection in very short-term memory

Target letters in briefly presented word displays are known to be better detected than when they are presented in anagram arrangements of the words’ letters. Target detection may have been higher for word displays either because Ss identified the words and then determined if a word possessed the target or because, in word displays, Ss could anticipate letters from the transitional probabilities (TRP) of letters in the language (TRP hypothesis). Detection in Experiment I was identical for words and for pseudowords, stimuli which were meaningless rearrangements of the words’ letters but which presented the words’ level of interletter TRP. Randomly rearranged displays, with lower TRP values, yielded lower detection rates. Experiment II showed that detection increased with TRP levels in nonword displays. The results support the TRP hypothesis and thus are consistent with a serial-scanning process in very short-term memory, but are also consistent with a special variant of a parallel process.     

Practiced card sorting for multiple targets

Ss were given extended practice in card sorting. Each card was inscribed with nine letters; on half the cards one letter was a “target.” With practice, the Ss could sort as fast for eight targets at once as for a single difficult target, while maintaining the same overall error rates. However, they did miss the difficult target itself more often when it occurred in the multiple-target condition than when they were searching for it alone.     

A Bayesian prediction of four-look recognition performance from one-look data

The hypothesis that a human O’s (S’s) performance in a visual recognition task can be modelled by Bayes’ theorem was investigated. Two Ss were run for 40 experimental sessions each. Their task was to specify the direction of the gap of tachistoscopically presented Landolt rings (Cs). There were four possible gap directions, and two experimental conditions. In one condition, S responded after each stimulus presentation. In the other, a fixed-observation condition, Ss responded after four consecutive presentations of a C. Exposure durations were such that performance under both conditions was greater than chance, but less than unity. Predictions of four-look performance from one-look data were made. Overall hit rates were predicted closely. The entire pattern of each S’s four-look data was also predicted reasonably well. Further tests of the model are currently under way.     

I recognize your face but I can’t remember your name: Further evidence on the tip-of-the-tongue phenomenon

Fifty faces of “famous” persons were used as stimuli to precipitate the tip-of-the-tongue (TOT) experience. Results showed that Ss in TOT states searched for target’s name by locating first his profession, where he was most often seen, and how recently. Ss also had accurate knowledge of the initial letters of target names, initial letters of similar sounding names, and numbers of syllables in target names. It was concluded that TOT states for to-be-remembered names are retrieved from semantic and episodie memory systems on the basis of verbal and imaginal encodings.     

Visual search under conditions of very rapid sequential Input rates

The purposes of the present experiment were to provide information on rate of information processing in visual perception and to determine the degree to which the “sequential blanking” effect found by Mayzner. Tresselt, and Cohen (1966) constituted a limitation on rapid sequential input rates. A 10-channel tachisto scope was employed that permitted controlled durations of each of the 10 channels and the 9 inter channel intervals. The S’s task was one of visual search or detection in which he searched for a target letter among noise letters. A temporal interval forced-choice procedure was used. In addition to varying the rate at which letters were sequentially presented, various irregular temporal spatial orders of presentation of the letter sequences were employed and the direction and orientation of the display in the visual field was varied as was also the spacing between adjacent stimuli. No evidence of “sequential blanking” was found either in terms of the detection criterion or in the Ss’ phenomenal reports. Detection performance was as good at a rate of 2 1/2 msec per letter as it was at a rate of 30 msec per letter.     

The effect of a visual indicator on rate of visual search: Evidence for processing control

Search rates were estirnated from response latencies in a visual search task of the type used by Atkinson, Holmgren, and Juola (1969), in which a S searches a small set of letters to determine the presence or absence of a predesignated target. Half of the visual displays contained a marker above one of the letters. The marked letter was the only one that had to be checked to determine whether or not the display contained the target. The presence of a marker in a display significantly increased the estimated rate of search, but the data clearly indicated that Ss did not restrict processing to the marked item. Letters in the vicinity of the marker were also processed. These results were interpreted as showing that Ss are able to exercise some degree of control over the search process in this type of task.     

Effects of noise letters upon the identification of a target letter in a nonsearch task

During a 1-sec tachistoscopic exposure, Ss responded with a right or left leverpress to a single target letter from the sets H and K or S and C. The target always appeared directly above the fixation cross. Experimentally varied were the types of noise letters (response compatible or incompatible) flanking the target and the spacing between the letters in the display. In all noise conditions, reaction time (RT) decreased as between-letter spacing increased. However, noise letters of the opposite response set were found to impair RT significantly more than same response set noise, while mixed noise letters belonging to neither set but having set-related features produced intermediate impairment. Differences between two target-alone control conditions, one presented intermixed with noise-condition trials and one presented separately in blocks, gave evidence of a preparatory set on the part of Ss to inhibit responses to the noise letters. It was concluded that S cannot prevent processing of noise letters occurring within about 1 deg of the target due to the nature of processing channel capacity and must inhibit his response until he is able to discriminate exactly which letter is in the target position. This discrimination is more difficult and time consuming at closer spacings, and inhibition is more difficult when noise letters indicate the opposite response from the targe     

Types and frequency of errors in visual search

The experimental method allowed false-positive as well as false-negative errors to be measured during visual search. Data were collected from eight Ss on four target-set size conditions on each of 25 days in order to determine whether the finding that search rate is independent of target-set size after practice might be attributable to a systematic variation in total error rate with set size. Even after practice, these Ss continued to search significantly faster for a single target than for target sets which were composed of five or more characters. Further, the incidence of total errors was much lower than in those studies in which search rate had been found to be independent of set size (i.e., parallel processing), even though these latter studies considered only the occurrence of false-negative errors. Additional analysis strongly suggests that: (1) attainment of parallel processing and a highly accurate performance are incompatible, and (2) verbal instructions alone are not sufficient to control the accuracy levels.     

Parallel perceptual processing and decisional strategies: A reinterpretation of the Shaw and LaBerge effect

A reinterpretation is offered for an effect found by Shaw and LaBerge (1971) in a tachistoscopic detection paradigm. Their Ss were instructed to “scan” the letters of a multiletter stimulus array in a particular sequence. The Ss were more accurate in identifying a target letter if it occurred earlier rather than later in the instructed sequence. Although Shaw and LaBerge interpreted this result as supporting a limited-capacity attentional mechanism, the result is also consistent with a nonattentional parallel processing conception: the payoff incentives used to encourage the correct “scanning sequence” could alter Ss’ postperceptual decisional strategy so as to produce the results obtained. Given the compatibility of a parallel processing conception with the results of Shaw and LaBerge and the results of other detection experiments, the need for postulating a spatial capacity limit or attentional mechanism is questioned.     

The recovery of a visually masked target

Ss were briefly shown pairs of letters under backward masking and disinhibitive backward masking conditions. For the backward masking condition, a single homogeneous flash of light (M1), varying in duration, followed the presentation of letters after a varying delay (IS11), and recognition of the target letters (TS) was found to be a function of M1 duration and ISI1. For the disinhibition condition, a variable second mask (M2) followed M1 after a variable delay (ISI2) and disinhibition of M1’s effect on TS recognition occurred. Provided the ISIs were adequate, a relatively powerful M2 wass found to disinhibit a moderate Ml’s effect on the TS. Current theories of visual masking were examined in the light of these findings.     

Is visual attention automatically attracted by one’s own name?

Subjects were presented with briefly exposed visual displays of words that were common first names with a length of four to six letters. In the main experiment, each display consisted of four words: two names shown in red and two shown in white. The subject’s task was to report the red names (targets), but ignore the white ones (distractors). On some trials the subject’s own name appeared as a display item (target or distractor). Presentation of the subject’s name as a distractor caused no more interference with report of targets than did presentation of other names as distractors. Apparently, visual attention was not automatically attracted by the subject’s own name.     

The relationship between cognitive,motor-kinesthetic,and oculomotor adaptation

The literature concerning adaptation to prism indicates that several adaptive mechanisms may be important. The particular mechanism or mechanisms involved depends (at least in part) upon the type of adaptive exposure. In the present study. three adaptive mechanisms (cognitive. oculomotor, and motor-kinesthetic) were investigated. Ss were asked to point in the dark at an illuminated target. The target was seen displaced from its veridical position due to a wedge prism placed before S’s right eye. The left eye was occluded. Ss then viewed their visual target pointing errors through the displacing prism without seeing any part of their bodies. One group of Ss was instructed to ignore these prism-induced errors and to continue pointing at the target’s visual position. A second group of Ss was instructed to compensate fully for their errors and to at tempt to eliminate them on all future trials. For the latter group errors were completely eliminated, while for Ss instructed to ignore their errors, relatively small improvement in visual target settings occurred. This improvement was called cognitive adaptation, since it depended on the S’s conscious control. In addition. for both conditions. evidence was found that allowing Ss to view their prism-induced pointing errors resulted in some form of motor-kinesthetic adaptation. This adaptation was hypothesized to represent a change in the judged position of the pointing hand relative to its felt position. It was concluded that this motor-kinesthetic adaptation was dependent, in part, upon cognitive information concerning the effects of the prism and that it serves to reduce conflict between cognitive and visual cues, i.e., between what S believes and what he sees.     

Effect of direction of sequential presentation and redundancy on short-term recognition memory

Short-term recognition memory was tested by presenting six letters, one after the other, followed by a target letter and having S indicate whether or not the target matched one of the six letters. Recognition memory for a letter was better when it was embedded in a six-letter word, rather than a nonword, and when it was included in a sequence presented left-to-right, rather than right-to-left (Experiment 1). Reducing the presentation rate from 4/sec to 2.5/sec largely eliminated the left-to-right effect (Experiment 2). The effect of direction of presentation was greater for redundant (Experiment 1) than for nonredundant sequences (Experiment 3) and was greater for Ss who more frequently formed a word out of the sequence (Experiments 1 and 2), but was no greater for words than nonwords (Experiments 1 and 2) and no greater for letter than for line-figure sequences (Experiment 3). These findings suggest that the left-to-right effect depends as much, or more, on “peripheral” processes (e.g., eye movements) as on “central” processes (e.g., reading).     

Neon colors illuminate reading units

The effect of syllable-size reading units on neon color was investigated in 6 experiments. The stimuli consisted of 5- or 7-letter words or pseudowords with a syllable break either just before or just after the middle (target) letter. The target letter was overlaid with a plaid of red and green lines that gave it an ambiguous neon color. The letters preceding the target were overlaid with a monochromatic grid (red or green), and the letters following the target were overlaid with the other color. Ss were significantly more likely to judge the target as more similar to the color of other letters within its syllable than colors of letters outside that unit. The effect was shown not to be an artifact of guessing strategy or eye movements. Word structure determined by orthography and morphology affected neon colors, but no effect was found for purely phonological units.     

Some evidence for a limited capacity parallel selfterminating process in simple visual search tasks.

An experiment was carried out in order to investigate the questions of exhaustive vs selfterminating and serial vs parallel processing in a simple visual search task. In the experiment, 1, 2 or 3 letters were placed on an imaginary circle round the fixation point. Two different letters were used, one of which was defined as the ‘signal’. Ss had to respond ‘yes’ when one or more signals were in the display, ‘no’ otherwise. The number of signals in the display was varied from ‘no signals’ to ‘all signals’.A decrease in latencies with increasing number of signals for a fixed number of elements presented was observed indicating a selfterminating search. A decrease in latencies with increasing number of elements when only signals were presented was taken as evidence for a parallel selfterminating process. A further analysis of the error data showed that a limited capacity system had to be assumed. It was shown that it was possible to construct the overall pattern of latencies over conditions from the error data obtained.     

Evidence for an addition to the reading scan hypothesis

Letters were tachistoscopically presented in pairs to the left or right of fixation for 40 msec. The pair consisted of a target letter (B, D, P, or T) and a noise letter (all other letters of the alphabet except I), with the noise letter appearing either to the inside or the outside of the stimulus letter. S’s task was to report verbally the target letter as fast as possible. Reaction times and number of errors indicated that there was more interference when the noise letter occurred further from the fixation point than the target letter for both the left and right visual field. Since a reading scan cannot account for the results in the right visual field, an outside-toward-fixation scan is proposed. An analysis of the different kinds of errors indicated that the outside to fixation scan is more primitive than the reading scan in that it produces less detailed information about the letters than does the reading scan.     

The repeated letter effect in the misspellings

The study consisted of a comparison of the spontaneous misspellings of a dysgraphic (L. H. Oswald) with the ease of perception and recall of similar misspellings by normal Ss. The main results were as follows: (1) Oswald frequently misspelled repeated letters in words (e.g., ELDERY). Similarly, normal Ss found repeated-letter misspellings more difficult to perceive and recall than nonrepeated-letter misspellings. (2) Oswald frequently misspelled repeated letters which were close together as in ANLYZE (for ANALYZE), but he rarely misspelled widely separated repeated letters as in MISSPELLNG. Similarly, normal Ss found repeated-letter misspellings hardest to perceive and recall when the repeated letters were close together, and very easy when they were widely separated. (3) Oswald misspelled the second of two repeated letters (as in ELDERY) more frequently than the first (as in EDERLY). Similarly, normal Ss found repeated-letter misspellings easier to perceive and recall when the first of the repeated letters was misspelled, as in EDERLY, than when the second was misspelled. (4) Oswald sometimes repeated a letter on his own, as in HABITITUATED—but more frequently he dropped a repeated letter as in ELDERY. However, repeated-letter misspellings involving deleted letters were easier for the normal Ss to recall than those involving deletions. Evidence suggesting that repeated phonemes induce analogous errors in normal speech production was discussed, and implications for general models of the serial order of speech behavior were pointed out.     

The effects of the binocular disparity differences between targets and maskers on visual search

A visual search for targets is facilitated when the target objects are on a different depth plane than other masking objects cluttering the scene. The ability of observers to determine whether one of four letters presented stereoscopically at four symmetrically located positions on the fixation plane differed from the other three was assessed when the target letters were masked by other randomly positioned and oriented letters appearing on the same depth plane as the target letters, or in front, or behind it. Three additional control maskers, derived from the letter maskers, were also presented on the same three depth planes: (1) random-phase maskers (same spectral amplitude composition as the letter masker but with the phase spectrum randomized); (2) random-pixel maskers (the locations of the letter maskers’ pixel amplitudes were randomized); (3) letter-fragment maskers (the same letters as in the letter masker but broken up into fragments). Performance improved with target duration when the target-letter plane was in front of the letter-masker plane, but not when the target letters were on the same plane as the masker, or behind it. A comparison of the results for the four different kinds of maskers indicated that maskers consisting of recognizable objects (letters or letter fragments) interfere more with search and comparison judgments than do visual noise maskers having the same spatial frequency profile and contrast. In addition, performance was poorer for letter maskers than for letter-masker fragments, suggesting that the letter maskers interfered more with performance than the letter-fragment maskers because of the lexical activity they elicit.     

The effects of coding procedure on human information transmission

Three different coding schemes, i.e., transformations between stimuli and responses, were used in a continuous information transmission situation. The stimuli were groups of binary digits and S was required to transform these into verbal equivalents of combinations formed by taking various sets of the English letters. Three codes, one based on communication theory, one based on Miller’s (1956) chunking hypothesis, and a combination of the first two were used. In addition, two levels of stimulus redundancy, zero and 0.5 were used. Time to complete the task and errors were the de-pendent variables. The Ss were run for twelve days. The basic result was that Ss transmitted information at a constant rate regardless of the code or redundancy level used.     

Processing of sequentially presented letters

The effect on the number of letters S can report of the duration of each sequentially presented letter was compared with that of processing time, defined as the time from the onset of a letter to the onset of the next letter. Four Ss were each shown 1250 common English words, from four to eight letters long, one letter at a time. Each letter acted as a visual noise field for the preceding letter. The duration of each letter and the interval between letters was varied independently. The S reported the letters he saw after each word was displayed. It was found that the processing time (onset to onset) predicted the number of letters correctly reported, regardless of the partition between on time and off time. A calculation was made of the number of milliseconds of on plus off time that are needed to ensure correct report of each letter. This time was independent of the duration of the processing time, but was positively correlated with the number of letters in the word. This correlation is probably in part artifactual, so that no claim can be made that it takes longer to process a letter of a long as compared to a short word.