Five-letter Words Research Articles

Age-related differences in spatiotemporal markers of gait stability during dual task walking

Increased stride-to-stride variability during walking characterizes gait instability and predicts falling in older adults. Walking while performing cognitive tasks (dual task walking) is also associated with increased risk of falling. The purpose of the study was to examine whether gait velocity and stride-to-stride variability in gait velocity differ in older adults compared with middle-aged and younger adults during normal and dual task walking conditions. Sixty older ( n = 20, mean age = 81 years), middle-aged ( n = 20, mean age = 48 years), and young adults ( n = 20, mean age = 25 years) participated in the study. Gait parameters were quantified with GAITRite ® instrumentation. In the dual task condition, participants spelled five-letter words in reverse while walking across the walkway. Across groups, gait velocity was slower ( p < 0.001) and stride-to-stride variability in gait velocity was greater ( p = 0.001) in dual task walking. Older subjects walked more slowly than did middle-aged and younger subjects and the difference in gait velocity was greatest in the dual task condition ( p < 0.05). Variability in stride velocity was increased in older subjects compared with middle-aged and younger subjects ( p < 0.05). Additionally, in older subjects, impaired walking performance was associated with impaired cognitive performance in dual task walking. The gait changes observed in dual task walking characterize decreased gait stability and indicate that cognitively demanding tasks during walking have a destabilizing effect on gait and may place older people at a greater risk of falling.

Feature detection and letter identification

Seeking to understand how people recognize objects, we have examined how they identify letters. We expected this 26-way classification of familiar forms to challenge the popular notion of independent feature detection (“probability summation”), but find instead that this theory parsimoniously accounts for our results. We measured the contrast required for identification of a letter briefly presented in visual noise. We tested a wide range of alphabets and scripts (English, Arabic, Armenian, Chinese, Devanagari, Hebrew, and several artificial ones), three- and five-letter words, and various type styles, sizes, contrasts, durations, and eccentricities, with observers ranging widely in age (3 to 68) and experience (none to fluent). Foreign alphabets are learned quickly. In just three thousand trials, new observers attain the same proficiency in letter identification as fluent readers. Surprisingly, despite this training, the observers—like clinical letter-by-letter readers—have the same meager memory span for random strings of these characters as observers seeing them for the first time. We compare performance across tasks and stimuli that vary in difficulty by pitting the human against the ideal observer, and expressing the results as efficiency. We find that efficiency for letter identification is independent of duration, overall contrast, and eccentricity, and only weakly dependent on size, suggesting that letters are identified by a similar computation across this wide range of viewing conditions. Efficiency is also independent of age and years of reading. However, efficiency does vary across alphabets and type styles, with more complex forms yielding lower efficiencies, as one might expect from Gestalt theories of perception. In fact, we find that efficiency is inversely proportional to perimetric complexity (perimeter squared over “ink” area) and nearly independent of everything else. This, and the surprisingly fixed ratio of detection and identification thresholds, indicate that identifying a letter is mediated by detection of about 7 visual features.

The relationship between word length and threshold character size in patients with central scotoma and eccentric fixation

Understanding limitations on text reading with eccentric fixation is of major concern in low vision research. Our objective was to determine, in patients with a central scotoma, whether threshold character size is similar for different word lengths and paragraphed texts. In 19 patients, we retrospectively analyzed the relationship between minimum readable character size for isolated words and text. Isolated letters, two, five, and ten-letter words and a paragraphed text were presented randomly through a scanning laser ophthalmoscope in eight different character sizes. Threshold character size varied according to the text stimulus (p<0.05). Threshold character sizes for single letters and two-letter words were matched (p>0.99), as were those for five-letter words, ten-letter words, and paragraphed text (p>0.99). Threshold character size for single letters and two-letter words was significantly lower than that measured with other text stimuli. Reading performance is influenced by a variety of factors such as crowding, contextual effects, visual span, degree of oculomotor adaptation needed, and frequency of a defined word. Globally, when reading with a central scotoma, it appears that within word characteristics have more impact than inter-word parameters on threshold character size.

Type-based bigram frequencies for five-letter words

Researchers often require subjects to make judgments that call upon their knowledge of the orthographic structure of English words. Such knowledge is relevant in experiments on, for example, reading, lexical decision, and anagram solution. One common measure of orthographic structure is the sum of the frequencies of consecutive bigrams in the word. Traditionally, researchers have relied on token-based norms of bigram frequencies. These norms confound bigram frequency with word frequency because each instance (i.e., token) of a particular word in a corpus of running text increments the frequencies of the bigrams that it contains. In this article, the authors report a set of type-based bigram frequencies in which each word (i.e., type) contributes only once, thereby unconfounding bigram frequency from word frequency. The authors show that type-based bigram frequency is a better predictor of the difficulty of anagram solution than is token-based frequency. These norms can be downloaded from www.psychonomic.org/archive/.

Visual word recognition: the first half second

We used magnetoencephalography (MEG) to map the spatiotemporal evolution of cortical activity for visual word recognition. We show that for five-letter words, activity in the left hemisphere (LH) fusiform gyrus expands systematically in both the posterior–anterior and medial–lateral directions over the course of the first 500 ms after stimulus presentation. Contrary to what would be expected from cognitive models and hemodynamic studies, the component of this activity that spatially coincides with the visual word form area (VWFA) is not active until around 200 ms post-stimulus, and critically, this activity is preceded by and co-active with activity in parts of the inferior frontal gyrus (IFG, BA44/6). The spread of activity in the VWFA for words does not appear in isolation but is co-active in parallel with spread of activity in anterior middle temporal gyrus (aMTG, BA 21 and 38), posterior middle temporal gyrus (pMTG, BA37/39), and IFG.

Letter position coding in printed word perception: Effects of repeated and transposed letters

We report four experiments investigating the effects of repeated and transposed letters in orthographic processing. Orthographically related primes were formed by removing one letter from the target word, by transposing two adjacent letters, or by replacing two adjacent letters with different letters. Robust masked priming in a lexical decision task was found for primes formed by removing a single letter (e.g., mircle-MIRACLE), and this was not influenced by whether or not the prime contained a letter repetition (e.g., balace vs. balnce as a prime for BALANCE ). Target words containing a repeated letter tended to be harder to respond to than words without a letter repetition, but the nonwords formed by removing a repeated letter (e.g., BALNCE) were no harder to reject than nonwords formed by removing a non-repeated letter (e.g., MIRCLE, BALACE). Significant transposition priming effects were found for 7-letter words (e.g., sevrice-SERVICE), and these priming effects did not vary as a function of the position of the transposition (initial, final, or inner letter pair). Priming effects disappeared when primes were formed by replacing the two transposed letters with different letters (e.g., sedlice-SERVICE), and five-letter words only showed priming effects with inner letter transpositions (e.g., ponit-POINT). We present a revised “open-bigram” scheme for letter position coding that accounts for these data.

Problem Variables that Promote Incubation Effects

AbstractThree studies sought to determine whether incubation effects could be reliably generated in a problem‐solving task. Experimental variables manipulated were the duration of the interval between two problem‐solving opportunities and the activity performed by the problem solvers during the interval. A multi‐solution anagram task was used which required problem solvers to generate five‐letter words from the letters in a ten‐letter “starter” word until they could produce no more words. After a break (the incubation period) the problem solvers returned to the anagram task anew. Some participants also engaged in an activity related to the anagram task during the break which was expected to prime potential solutions that would emerge during the second problem‐solving attempt. In all conditions problem solvers were able to generate new responses after the break, thus demonstrating a reliable incubation effect. The optimal incubation period was between 15 and 30 min long. The priming task increased the number of solutions to the anagram task on the second attempt, suggesting that exposure to solution ideas during the incubation period may facilitate an incubation effect during problem solving.

Implicit memory formation in sedated ICU patients after cardiac surgery

Recent research into memory formation under sedation has generated conflicting results. We investigated explicit and implicit memory in ICU patients during moderate to deep propofol sedation following cardiac surgery. Two different methods of memory testing were used; (1). free-association (F-A) word-pair testing (n=33) to test conceptual implicit memory and (2). process dissociation procedure (PDP) (n=26) to detect perceptual implicit and explicit memory. One hour after surgery, whilst sedated, the F-A group received one of two lists of 10 category-exemplar word-pairs through headphones, while the PDP group was presented with one of two lists of 16 five-letter words. When awake and co-operative, the F-A group was tested using F-A testing, and the PDP group was tested using the PDP. The F-A group had a mean (SD) correct response rate of 7 (9)% for the target list, and 9 (8)% for the distractor list. The PDP group had a mean (SD) correct response rate of 11 (14) and 10 (13)% for the inclusion and exclusion lists, respectively, with mean correct response rates of 13 (14)% for both the corresponding distractor lists. Neither group showed any significant differences between their responses and a list of distractor words (Wilcoxon tests). We found no evidence for memory formation in post-cardiac surgery patients under moderate to deep propofol sedation.

Compound Pre-Access Decomposition: Effects of Constituent Disruption

In this study, we report three experiments that investigate whether recognition of existing English compounds is dependent on the recognition of their constituent morphemes. A constituent disruption paradigm was employed with compounds of fixed length, but variable constituent length. The results of Experiment 1 confirmed that disrupting a single character in a three-character word by replacing it with a crosshatch (e.g., way → w#y) interfered with recognition rates more than the disruption of a single character of a five-letter word (e.g., drive → dr#ve). However, in Experiment 2, when these constituents were embedded in eight-character compounds (e.g., driveway), no differential effect of constituent disruption was found for either naming accuracy or latency. In Experiment 3, this effect was replicated in a masked priming lexical decision paradigm in which disrupted compounds served as primes and intact compounds served as targets. The results of the three experiments were interpreted to offer counter-evidence to the claim that compound recognition is dependent on the prelexical recognition of constituent morphemes. We argue that although English compound processing may indeed be characterized by both whole-word recognition and constituent activation, access to individual morphemes is not a necessary condition in the recognition process.

Is the optimal viewing position in reading influenced by familiarity of the letter string?

An optimal viewing position (OVP) for word recognition has been proposed by several authors. The location of this position would be located at the center of the word or just left of it. Several hypotheses ranging from perceptual to hemispheric factors have been proposed to explain this phenomenon. In the experiment presented here, the effect of the nature of the stimulus was tested: word, pseudo-word, or nonword on the existence and location of this position. Little research has investigated this issue. Five-letter words, pseudo-words, and non-words were presented, with the subject fixating initially on one of the five possible letter positions. The number of letters correctly identified and reading performance were recorded for each stimulus. Results show that an initial fixation on the third letter entails better letter identification for all kinds of stimuli. However, in terms of reading, only word reading benefit from a fixation on the third letter. These results are discussed in relation to the different hypotheses of OVP in reading. These are (1) hemispheric specialization, (2) reading habits, and (3) lexical constraints.

Parafoveal processing in word recognition.

Two experiments investigated the degree to which properties of a word presented in the parafovea influenced the time to process a word undergoing concurrent foveal inspection. In Experiment 1, subjects viewed a set of five-letter words at a fixed point, with words in parafoveal vision varying in length, word frequency, and both the type and token frequency of occurrence of their initial three letters. The results showed that the frequency of the target and the type frequency of its initial letters influenced foveal fixation time. In Experiment 2, subjects executed a sequence of saccades before initial fixation on the experimental items. Under these circumstances, fixation time was shorter overall. Lexical properties of parafoveal words had no effect on foveal processing, but the length and the type frequency of their initial letters exerted a strong influence. Parafoveal-on-foveal effects of this form are incompatible with models of reading in which attention is allocated sequentially to successive words. The data are more consistent with the proposition that foveal and parafoveal processing occurs in parallel, with processing distributed over a region larger than a single word. Subsidiary analyses showed little influence of any of the manipulated variables on saccade extent.

Parafoveal processing in word recognition

Two experiments investigated the degree to which properties of a word presented in the parafovea influenced the time to process a word undergoing concurrent foveal inspection. In Experiment 1, subjects viewed a set of five-letter words at a fixed point, with words in parafoveal vision varying in length, word frequency, and both the type and token frequency of occurrence of their initial three letters. The results showed that the frequency of the target and the type frequency of its initial letters influenced foveal fixation time. In Experiment 2, subjects executed a sequence of saccades before initial fixation on the experimental items. Under these circumstances, fixation time was shorter overall. Lexical properties of parafoveal words had no effect on foveal processing, but the length and the type frequency of their initial letters exerted a strong influence. Parafoveal-on-foveal effects of this form are incompatible with models of reading in which attention is allocated sequentially to successive words. The data are more consistent with the proposition that foveal and parafoveal processing occurs in parallel, with processing distributed over a region larger than a single word. Subsidiary analyses showed little influence of any of the manipulated variables on saccade extent.

The recognition potential and word priming.

The effect of priming on the latency of the recognition potential (RP) was tested using rapid stream stimulation. Subjects detected five-letter words in a stream of nonword images. Lifting the right index finger signalled detection of a word. Rapid responses were rewarded and false alarms were penalized. Just before generating an image stream, a computer briefly displayed either the specific target word or or five-letter string that indicated the target was any one of ten previously studied words. Precise target specification was expected to produce more rapid detection than the provision of less definite information. Since the RP was thought to reflect the speed of perception, it was predicted that its latency would be less when the target word was beforehand than when less specific information was provided. The results for 10 subjects confirmed the hypothesis.

Frequency of word usage and perceived word difficulty: Ratings of Kučera and Francis words

Twenty-four judges estimated the conceptual difficulty level of 870 five-letter words, using a 5-point scale. The words were selected from three word-frequency categories (1, 5–10, and 50–3,562/million) based on the word counts provided by Kučera and Francis (1967). The ratings were reliable. Tables in this paper list the means and standard deviations of the ratings for each word. Reaction time (RT) for valid word identification was tested in 20 subjects, using four sets of 50 words designed to test the effects of word frequency and word difficulty. RT was longer for more difficult words when word frequency was held constant. A word-frequency effect on RT was present when difficulty was held constant. The relationship of the results to subjective estimates of word familiarity is discussed.

Spatial Representations of Words and Nonwords

The first two experiments investigated whether the representations of words, besides being unitary, are also spatial in nature. Subjects were required to search for target letters in either five-letter words or five-letter nonwords. They were instructed to press the right-side key for one target and the left-side key for the other target. The center item of the letter string was always at fixation. Targets appeared one at a time, located at the second (left side) or the fourth (right side) position within the letter string.The results showed that: a) responses to targets within words were faster than responses to targets within nonwords (the word-superiority effect); b) responses to compatible stimulus-response pairings were faster than responses to incompatible stimulus-response pairings (the spatial compatibility, or, more precisely, the Simon effect); and c) in Experiment 2, leftside targets were responded to faster than right-side targets within nonwords (the left-right scanning effect). It was concluded that representations of both words and nonwords are spatial in nature. Experiment 3 was aimed at testing whether the spatial layout of the representations of words is always along the left-right horizontal dimension, regardless of the topographic transformation of the stimulus. The same words and nonwords used in the previous experiments were shown vertically and the subjects were required to make left-right discriminative responses to upper and lower target letters. The results showed the word-superiority effect but no spatial compatibility effects. It was concluded that the representation of a vertically presented word is vertically arranged.

Neighborhood frequency effects and letter visibility in visual word recognition.

Two experiments are described that measured lexical decision latencies and errors to five-letter French words with a single higher frequency orthographic neighbor and control words with no higher frequency neighbors. The higher frequency neighbor differed from the stimulus word by either the second letter (e.g., ASTRE-AUTRE) or the fourth letter (CHOPE-CHOSE). Neighborhood frequency effects were found to interact with this factor, and significant interference was observed only to CHOPE-type words. The effects of neighborhood frequency were also found to interact with the position of initial fixation in the stimulus word (either the second letter or the fourth letter). Interference was greatly reduced when the initial fixation was on the critical disambiguating letter (i.e., the letter P in CHOPE). Moreover, word recognition was improved when subjects initially fixated the second letter relative to when they initially fixated the fourth letter of a five-letter word, but this second-letter advantage practically disappeared when the stimulus differed from a more frequent word by its fourth letter. The results are interpreted in terms of the interaction between visual and lexical factors in visual work recognition.

Tachistoscopic presentation of verbal stimuli for assessing cerebral dominance: Reliability data and some practical recommendations

reliability data point to rather high test-retest correlations (⩾0.65) for VHF data with four-and five-letter words as stimuli, but replicate previous findings that the first test score correlates poorly with later test scores. The same results are obtained for accuracy and latency data, though small differences exist. All laterality indices lead to the same conclusions and have high intercorrelations. The point-biserial correlation coefficient is, however, a slightly more reliable index of naming latency than the mere difference between LVF and RVF. No such superiority is found for the indices based on accuracy data. The results also point to the need to present a sufficient number of stimuli before firm conclusions can be drawn.

A Comparison of Computer Input Devices: Linus Pen, Mouse, Cursor Keys and Keyboard

Four input devices were compared in a data entry task by speed and accuracy scores. The input devices were: Linus pen (a handwriting recognition system), optical mouse, cursor keys, and alphabetic keys on a keyboard. Data entry consisted of twenty 5-letter words and 100 single letters. Two different screen designs (QWERTY and ALPHA) were used for the mouse and cursor keys conditions. Results showed the keyboard to be fastest and the cursor keys to be slowest in data entry. The mouse and Linus pen had comparable latency scores. Overall, five-letter words were entered faster than five single letters. Latency decreased over trials, and ALPHA conditions required more time than QWERTY conditions. The Linus pen was the least accurate input device. The cursor QWERTY condition produced the highest accuracy scores for letter entry while the keyboard produced the highest accuracy scores for word entry.

Lexical Decision, Parafoveal Eccentricity and Visual Hemifield

The effect of the eccentricity of parafoveal stimulation on a lexical decision task was studied using stimuli presented to the two visual hemifield. Five-letter word and nonword stimuli were presented to three parafoveal locations ranging over 1° angle of eccentricity. Subjects responded manually. The results of the analyses indicated that the average RT to words was approximately 48 msec. shorter than to nonwords. The average RT to a stimulus presented to the RVF was approximately 11 msec. shorter than to a stimulus presented to the LVF. As parafoveal location became more eccentric, RT to all stimuli increased by approximately 37 msec. per degree of eccentricity. A very significant interaction was found between the visual hemifield stimulated and the direction of response to the type of stimulus presented (word/nonword).

Spatial extent of attention to letters and words.

The spatial extent of attention to visually presented letters and words was investigated using a probe technique. The primary task required subjects to categorize (a) five-letter words, or to categorize the middle letter of (b) five-letter words or (c) five-letter nonwords. The probe task required the subjects to respond when the digit 7 appeared in one of the five letter positions. Probe trials were inserted at the onset of letter and word processing in Experiment 1 and 500 msec after letter and word processing in Experiment 2. In both experiments, probe trials produced a V-shaped function of reaction times across probe positions for the letter-categorization task for word and nonword stimulus conditions. In contrast, a relatively flat reaction time function was found for the word-categorization tasks. An analysis of the data based on a quantitative model of attentional spotlight distributions suggests that the spotlight width in the letter tasks is one letter space, and the spotlight width in the word task is typically five spaces.