Target Letter Research Articles

The first letter position effect in visual word recognition: The role of spatial attention.

A prominent question in visual word recognition is whether letters within a word are processed in parallel or in a left to right sequence. Although most contemporary models posit parallel processing, this notion seems at odds with well-established serial position effects in word identification that indicate preferential processing for the initial letter. The present study reports 4 experiments designed to further probe the locus of the first position processing advantage. The paradigm involved masked target words presented for short durations and required participants to subsequently select from 2 alternatives, 1 which was identical to the target and 1 that differed by a single letter. Experiment 1 manipulated the case between the target and the alternatives to ensure that previous evidence for a first position effect was not due to simple perceptual matching. The results continued to yield a robust first position advantage. Experiment 2 attempted to eliminate postperceptual decision processes as the explanatory mechanism by presenting single letters as targets and requiring participants to select an entire word that contained the target letter at different positions. Here the first position advantage was eliminated, suggesting postperceptual decision processes do not underlie the effect. The final 2 experiments presented masked stimuli either all vertically (Experiment 3) or randomly intermixed vertical and horizontal orientation (Experiment 4). In both cases, a robust first position advantage was still obtained. The authors consider alternative interpretations of this effect and suggest that these results are consistent with a rapid deployment of spatial attention to the beginning of a target string which occurs poststimulus onset. (PsycINFO Database Record

Effects of task-irrelevant grouping on visual selection in partial report.

Perceptual grouping modulates performance in attention tasks such as partial report and change detection. Specifically, grouping of search items according to a task-relevant feature improves the efficiency of visual selection. However, the role of task-irrelevant feature grouping is not clearly understood. In the present study, we investigated whether grouping of targets by a task-irrelevant feature influences performance in a partial-report task. In this task, participants must report as many target letters as possible from a briefly presented circular display. The crucial manipulation concerned the color of the elements in these trials. In the sorted-color condition, the color of the display elements was arranged according to the selection criterion, and in the unsorted-color condition, colors were randomly assigned. The distractor cost was inferred by subtracting performance in partial-report trials from performance in a control condition that had no distractors in the display. Across five experiments, we manipulated trial order, selection criterion, and exposure duration, and found that attentional selectivity was improved in sorted-color trials when the exposure duration was 200 ms and the selection criterion was luminance. This effect was accompanied by impaired selectivity in unsorted-color trials. Overall, the results suggest that the benefit of task-irrelevant color grouping of targets is contingent on the processing locus of the selection criterion.

Cross-modal attention influences auditory contrast sensitivity: Decreasing visual load improves auditory thresholds for amplitude- and frequency-modulated sounds.

We used a cross-modal dual task to examine how changing visual-task demands influenced auditory processing, namely auditory thresholds for amplitude- and frequency-modulated sounds. Observers had to attend to two consecutive intervals of sounds and report which interval contained the auditory stimulus that was modulated in amplitude (Experiment 1) or frequency (Experiment 2). During auditory-stimulus presentation, observers simultaneously attended to a rapid sequential visual presentation-two consecutive intervals of streams of visual letters-and had to report which interval contained a particular color (low load, demanding less attentional resources) or, in separate blocks of trials, which interval contained more of a target letter (high load, demanding more attentional resources). We hypothesized that if attention is a shared resource across vision and audition, an easier visual task should free up more attentional resources for auditory processing on an unrelated task, hence improving auditory thresholds. Auditory detection thresholds were lower-that is, auditory sensitivity was improved-for both amplitude- and frequency-modulated sounds when observers engaged in a less demanding (compared to a more demanding) visual task. In accord with previous work, our findings suggest that visual-task demands can influence the processing of auditory information on an unrelated concurrent task, providing support for shared attentional resources. More importantly, our results suggest that attending to information in a different modality, cross-modal attention, can influence basic auditory contrast sensitivity functions, highlighting potential similarities between basic mechanisms for visual and auditory attention.

Spatio-temporal dynamics of working memory maintenance and scanning of verbal information.

During verbal communication, humans briefly maintain mental representations of speech sounds conveying verbal information, and constantly scan these representations for comparison to incoming information. We determined the spatio-temporal dynamics of such short-term maintenance and subsequent scanning of verbal information, by intracranially measuring high-gamma activity at 70-110Hz during a working memory task. Patients listened to a stimulus set of two or four spoken letters and were instructed to remember those letters over a two-second interval, following which they were asked to determine if a subsequent target letter had been presented earlier in that trial's stimulus set. Auditory presentation of letter stimuli sequentially elicited high-gamma augmentation bilaterally in the superior-temporal and pre-central gyri. During the two-second maintenance period, high-gamma activity was augmented in the left pre-central gyrus, and this effect was larger during the maintenance of stimulus sets consisting of four compared to two letters. During the scanning period following target presentation, high-gamma augmentation involved the left inferior-frontal and supra-marginal gyri. Short-term maintenance of verbal information is, at least in part, supported by the left pre-central gyrus, whereas scanning by the left inferior-frontal and supra-marginal gyri. The cortical structures involved in short-term maintenance and scanning of speech stimuli were segregated with an excellent temporal resolution.

Visual Recognition of Graphic Variants of Amharic Letters: Psycholinguistic Experiments

One of the problems of Amharic orthography is a lack of consistency where the four Amharic sounds (/h/, /ʔ/, /s/ and /s’/) are mapped onto more than a single letter. The objective of these psychological experiments was to investigate the visual recognition of the graphic variants of the letters, both in isolation and within words. The experiments involved computation of the frequency counts of the letters in the Ten Ten Corpus for Amharic and the result revealed that there is a clear pattern of preference for the letters: the letters representing /h/ had the pattern , the letters representing /ʔ/ had the pattern , the letters representing /s/ had the pattern , and the letters representing /s’/ had the pattern in descending order of frequency. Similarly, the experiments indicated that frequency counts are significantly related to visual recognition of a letter, with the more frequent letters recognized faster with fewer errors. It was also observed that the target letters were recognized with a shorter reaction time when they were paired with themselves, but the recognition time was longer when they occurred with their graphic variants. Moreover, significantly higher percentage of errors were made when the target letters were matched with their graphic variants or their distractors in the alphabet recognition task. Similar patterns were also observed in the lexical decision task when the target letters were presented in words and pseudo-words. More rigorous psycholinguistic experiments, which will involve a large number of participants, are recommended to validate the results of the current experiments.

Visual Search for Letters in the Right vs. Left Visual Hemifields: The Role of Perceptual Load and Set

The aim of the study was to better understand interconnection of visual attention, word processing and visual field asymmetries. Three experiments investigated visual search for a prespecified letter in displays containing 6-letter words or non-words placed 7 degrees left and right to the fixation, with a variable target letter position within word and non-word strings. In Experiment 1, two letter strings of the same type (either words or non-words) were presented to both sides of the visual field. In Experiment 2, there was only one letter string presented right or left to the fixation. In Experiment 3, two letter strings presented to both sides of the visual field were of different type (one word and one non-word). RT and accuracy data were collected. The results of Experiment 1 provide evidence for serial search for a letter within a word in the left visual field (LVF) and within a non-word in the right visual field (RVF) and parallel search for a letter within a non-word in the LVF and within a word in the RVF. The results of Experiment 3 were similar except for serial search for words in RVF. In Experiment 2, where perceptual load was twice lower, the search within both types of letter strings in both hemifields was serial. These results demonstrate the influence of the perceptual load and readiness to process a certain type of letter string, on the observers' choice of search strategy.

Naso-Temporal Asymmetries: Suppression of Emotional Faces in the Temporal Visual Hemifield.

An ongoing debate exists regarding the possible existence of a retino-tectal visual pathway projecting to the amygdala, which would rapidly process information involving threatening or behaviorally-relevant stimuli. It has been suggested that this route might be responsible for the involuntary capture of attention by potentially dangerous stimuli. In separate studies, anatomical evidence has suggested that the retino-tectal pathway relies essentially on projections from the nasal hemiretina (temporal visual field). In this study, we chose to take advantage of this anatomical difference to further investigate whether emotional facial expressions are indeed processed through a subcortical pathway. Using EEG, participants performed a monocular spatial attention paradigm in which lateralized, task-irrelevant distractors were presented, followed by a target. The distractors were fearful faces that appeared either in nasal or temporal visual hemifield (by virtue of their monocular presentations), while the neutral face was presented simultaneously on the opposite side. Participants were asked to identify a target letter that appeared subsequently in the nasal or temporal visual hemifield. Event-related potentials (ERPs) results revealed that fearful faces appearing in the temporal visual hemifield produced a strong inhibitory response, while a negative deflection reflecting attentional capture followed presentations of fear in the nasal hemifield. These effects can be explained by a greater sensitivity of the subcortical pathway for emotional stimuli. Fearful faces conveyed through this route are processed more effectively, consequently necessitating more vigorous suppression in order for targets to be dealt with adequately.

Reward interacts with modality shift to reduce cross-modal conflict.

Previous studies have shown that reward can enhance cognitive control and reduce conflict in visual processing. Here we investigate (a) whether and how reward influences cross-modal conflict control and (b) how the shift of attention across modalities modulates the effect of reward on cross-modal conflict control. In four experiments, a cue indicating the reward availability of a given trial (reward vs. no reward) was presented prior to a target. The target was either a visual or an auditory letter, which was accompanied by a distracting letter from the other modality. The identity of the distracting letter was either the same as or different from the identity of the target letter (congruent vs. incongruent). When the cue modality was constant (Experiment 1) or changed across different experimental blocks (Experiment 3), the interference effect (i.e., the response time difference between incongruent and congruent trials) was smaller following a reward cue than a no-reward cue, suggesting that reward can reduce cross-modal conflict. In contrast, when the cue modality was changed trial-by-trial in an unpredictable way (Experiments 2 and 4), reward reduced cross-modal conflict only when the cue and the target were from different modalities and had a long stimulus onset asynchrony (SOA) between them but not when they shared the same modality or had a short SOA between them. These results suggest that reward can facilitate cross-modal conflict resolution, and this effect may critically depend on both the preparatory state between the cue and the target and timing to initiate cognitive control.

Detecting distortions of peripherally presented letter stimuli under crowded conditions.

When visual features in the periphery are close together they become difficult to recognize: something is present but it is unclear what. This is called "crowding". Here we investigated sensitivity to features in highly familiar shapes (letters) by applying spatial distortions. In Experiment1, observers detected which of four peripherally presented (8 deg of retinal eccentricity) target letters was distorted (spatial 4AFC). The letters were presented either isolated or surrounded by four undistorted flanking letters, and distorted with one of two types of distortion at a range of distortion frequencies and amplitudes. The bandpass noise distortion ("BPN") technique causes spatial distortions in Cartesian space, whereas radial frequency distortion ("RF") causes shifts in polar coordinates. Detecting distortions in target letters was more difficult in the presence of flanking letters, consistent with the effect of crowding. The BPN distortion type showed evidence of tuning, with sensitivity to distortions peaking at approximately 6.5 c/deg for unflanked letters. The presence of flanking letters causes this peak to rise to approximately 8.5 c/deg. In contrast to the tuning observed for BPN distortions, RF distortion sensitivity increased as the radial frequency of distortion increased. In a series of follow-up experiments, we found that sensitivity to distortions is reduced when flanking letters were also distorted, that this held when observers were required to report which target letter was undistorted, and that this held when flanker distortions were always detectable. The perception of geometric distortions in letter stimuli is impaired by visual crowding.

Ask the pendulum: personality predictors of ideomotor performance.

For centuries, people have asked questions to hand-held pendulums and interpreted their movements as responses from the divine. These movements occur due to the ideomotor effect, wherein priming or thinking of a motion causes muscle movements that end up swinging the pendulum. By associating particular swinging movements with “yes” and “no” responses, we investigated whether pendulums can aid decision-making and which personality traits correlate with this performance. Participants () completed a visual detection task in which they searched for a target letter among rapidly presented characters. In the verbal condition, participants stated whether they saw the target in each trial. In the pendulum condition, participants instead mentally “asked” a hand-held pendulum whether the target was present; particular motions signified “yes” and “no”. We measured the accuracy of their responses as well as their sensitivity and bias using signal detection theory. We also assessed four personality measures: locus of control (feelings of control over one’s life), transliminality (sensitivity to subtle stimuli), need for cognition (preference for analytical thinking), and faith in intuition (preference for intuitive thinking). Overall, locus of control predicted verbal performance and transliminality predicted pendulum performance. Accuracy was low in both conditions (verbal: 57%, pendulum: 53%), but bias was higher in the verbal condition (). We confirmed this bias difference in a second study (, ). Our results suggest that people have different decision strategies when using a pendulum compared to conscious guessing. These findings may help explain why some people can answer questions more accurately with pendulums and Ouija boards. More broadly, identifying the differences between ideomotor and verbal responses could lead to practical ways to improve decision-making.

The Role of Cognitive Load in Intentional Forgetting Using the Think/No-Think Task.

We investigated the role of cognitive control in intentional forgetting by manipulating working memory load during the think/no-think task. In two experiments, participants learned a series of cue-target word pairs and were asked to recall the target words associated with some cues or to avoid thinking about the target associated with other cues. In addition to this, participants also performed a modified version of the n-back task which required them to respond to the identity of a single target letter present in the currently presented cue word (n=0 condition, low working memory load), and in either the previous cue word (n=1 condition, high working memory load, Experiment 1) or the cue word presented two trials previously (n=2 condition, high working memory load, Experiment 2). Participants' memory for the target words was subsequently tested using same and novel independent probes. In both experiments it was found that although participants were successful at forgetting on both the same and independent-probe tests in the low working memory load condition, they were only successful at forgetting on the same-probe test in the high working memory load condition. We argue that our findings suggest that the high load working memory task diverted attention from direct suppression and acted as an interference-based strategy. Thus, when cognitive resources are limited participants can switch between the strategies they use to prevent unwanted memories from coming to mind.

Conflict adaptation and interference suppression in stroke-induced aphasia: Evidence from multiple-single case studies

Conflict adaptation and interference suppression in stroke-induced aphasia: Evidence from multiple-single case studies

Impaired visual processing in patients with insomnia disorder revealed by a dissociation in visual search.

Insomnia disorder is associated with both subjective and objective daytime impairments. In particular, cognitive impairments are frequently reported. However, little is known about the effects of this pathology on perceptual processes. In this study we aim at evaluating the effect of insomnia disorder on visual processing by employing a visual search paradigm. Twenty-three patients with insomnia disorder and 20healthy age- and sex-matched control subjects participated in the study. After a polysomnographic recording night patients performed a visual search task in which they had to respond to the presence/absence of a target (letter T) embedded into a set of distractors (letters Os, Xs or Ls). Target's salience and distractors' numerosity were manipulated, while accuracy and reaction times were recorded as dependent variables. The results mainly confirmed the typical effects of a visual search task. An overall delay in performing the task was observed for patients with insomnia disorder. However, distinguishing the reaction times to stimuli containing the target from reaction times to stimuli in which the target was absent, the clinical group differed from controls solely in the condition of target absent. The performance (reaction times) of the subjects correlated with the age in the control group, whereas no correlation between reaction times and age, disease duration and quality of sleep was found in patients with insomnia disorder. These results experimentally demonstrate the presence of a daytime impairment in patients with insomnia disorder revealed by a dissociation in visual search, and are discussed in the light of the hyperarousal concept of insomnia.

Are the final letters of a parafoveal word used by developing readers? Evidence from a single word reading task

A recent study in isolated word reading (Khelifi et al., 2015) reported that word identification was facilitated in developing readers when a target was preceded parafoveally by a full preview (a preview containing all the target letters) but not by a partial preview (a preview containing only the first three letters of the target). While this result leads to wonder about contribution of the final letters in the preview benefit, two reasons could explain why partial preview does not provide any facilitation effect. First, lexical competition could arise between the partial preview and the target word. Second, an incompatibility between the partial preview and the target word at the visual level might disrupt the activation. The present study aimed to examine which of these reasons is the most likely. Third graders, fifth graders and expert readers performed a lexical decision task. Before being foveally displayed, a target was parafoveally previewed for a short time. It could be fully previewed or partially previewed. A facilitation effect was observed in fifth graders and expert readers when the target was fully previewed but not when it was partially previewed. The more probable explanation for the lack of an effect in the partial preview lies in a disruption at the visual processing level rather than a lexical competition between the target and the preview. In third graders, no facilitation effect was observed whatever the preview condition. In contrast to fifth graders and expert readers, the results in third graders evidenced a limit in the processing of the more eccentric letters of a parafoveal word.

TRANSLITERASI NASKAH MANUSKRIP JAWA: UPAYA NYATA PENYEDIAAN BAHAN PEMBELAJARAN DAN PENELITIAN KEBUDAYAAN JAWA

The aim of research is give lesson materials and research about Javanese manuscripts. The method used to explore manuscript is transliteration. Namely, transfering from source letter to target letter, and more transliteration from old Javanese language to Indonesian language.The reaearch desaign is R and D (research and development). The subject matter are students of Ekspresi Tulis Lanjut , in class G, H, and A in javanese department. The collecting of data used to observation, dokument analysis, and tasks. The object of research is Javanese manuscripts as the result of translation in the class.The results of this research are materials javanese manuscripts, namely: (1) serat Darma laksita, (2) Serat Kudhup sari, and (3) Serat Kumandaka. The third of Javanese manuscripts contens etics, relegion and aestetic that very important for lesson and research. The form of manuscripts are tembang Macapat and gerongan songs. The manuscripts letter can read clearly and easely. Finnaly, the results of research very important for students, teachers, lecturer, and all of academics people.Key words: javanese manuscript, transliteration

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.

What a Simple Letter-Detection Task Can Tell Us About Cognitive Processes in Reading

Understanding reading is a central issue for psychology, with major societal implications. Over the past five decades, a simple letter-detection task has been used as a window on the psycholinguistic processes involved in reading. When readers are asked to read a text for comprehension while marking with a pencil all instances of a target letter, they miss some of the letters in a systematic way known as the missing-letter effect. In the current article, we review evidence from studies that have emphasized neuroimaging, eye movement, rapid serial visual presentation, and auditory passages. As we review, the missing-letter effect captures a wide variety of cognitive processes, including lexical activation, attention, and extraction of phrase structure. To account for the large set of findings generated by studies of the missing-letter effect, we advanced an attentional-disengagement model that is rooted in how attention is allocated to and disengaged from lexical items during reading, which we have recently shown applies equally to listening.

Is nevtral NEUTRAL? Visual similarity effects in the early phases of written-word recognition.

For simplicity, contemporary models of written-word recognition and reading have unspecified feature/letter levels-they predict that the visually similar substituted-letter nonword PEQPLE is as effective at activating the word PEOPLE as the visually dissimilar substituted-letter nonword PEYPLE. Previous empirical evidence on the effects of visual similarly across letters during written-word recognition is scarce and nonconclusive. To examine whether visual similarity across letters plays a role early in word processing, we conducted two masked priming lexical decision experiments (stimulus-onset asynchrony = 50ms). The substituted-letter primes were visually very similar to the target letters (u/v in Experiment 1 and i/j in Experiment 2; e.g., nevtral-NEUTRAL). For comparison purposes, we included an identity prime condition (neutral-NEUTRAL) and a dissimilar-letter prime condition (neztral-NEUTRAL). Results showed that the similar-letter prime condition produced faster word identification times than the dissimilar-letter prime condition. We discuss how models of written-word recognition should be amended to capture visual similarity effects across letters.

Prospective memory mediated by interoceptive accuracy: a psychophysiological approach.

Previous studies on prospective memory (PM), defined as memory for future intentions, suggest that psychological stress enhances successful PM retrieval. However, the mechanisms underlying this notion remain poorly understood. We hypothesized that PM retrieval is achieved through interaction with autonomic nervous activity, which is mediated by the individual accuracy of interoceptive awareness, as measured by the heartbeat detection task. In this study, the relationship between cardiac reactivity and retrieval of delayed intentions was evaluated using the event-based PM task. Participants were required to detect PM target letters while engaged in an ongoing 2-back working memory task. The results demonstrated that individuals with higher PM task performance had a greater increase in heart rate on PM target presentation. Also, higher interoceptive perceivers showed better PM task performance. This pattern was not observed for working memory task performance. These findings suggest that cardiac afferent signals enhance PM retrieval, which is mediated by individual levels of interoceptive accuracy.This article is part of the themed issue ‘Interoception beyond homeostasis: affect, cognition and mental health’.

Increased Early Processing of Task-Irrelevant Auditory Stimuli in Older Adults.

The inhibitory deficit hypothesis of cognitive aging posits that older adults’ inability to adequately suppress processing of irrelevant information is a major source of cognitive decline. Prior research has demonstrated that in response to task-irrelevant auditory stimuli there is an age-associated increase in the amplitude of the N1 wave, an ERP marker of early perceptual processing. Here, we tested predictions derived from the inhibitory deficit hypothesis that the age-related increase in N1 would be 1) observed under an auditory-ignore, but not auditory-attend condition, 2) attenuated in individuals with high executive capacity (EC), and 3) augmented by increasing cognitive load of the primary visual task. ERPs were measured in 114 well-matched young, middle-aged, young-old, and old-old adults, designated as having high or average EC based on neuropsychological testing. Under the auditory-ignore (visual-attend) task, participants ignored auditory stimuli and responded to rare target letters under low and high load. Under the auditory-attend task, participants ignored visual stimuli and responded to rare target tones. Results confirmed an age-associated increase in N1 amplitude to auditory stimuli under the auditory-ignore but not auditory-attend task. Contrary to predictions, EC did not modulate the N1 response. The load effect was the opposite of expectation: the N1 to task-irrelevant auditory events was smaller under high load. Finally, older adults did not simply fail to suppress the N1 to auditory stimuli in the task-irrelevant modality; they generated a larger response than to identical stimuli in the task-relevant modality. In summary, several of the study’s findings do not fit the inhibitory-deficit hypothesis of cognitive aging, which may need to be refined or supplemented by alternative accounts.