Interkey Intervals Research Articles

The fluency vs. disfluency dichotomy in writing processes as reflected in the structure of the inter-key intervals empirical distribution

ABSTRACT The broader aim of this study is the corpus-based investigation of the written language production process. To this end, temporal markers have been keylog recorded alongside the writing processes to exploit pauses to segment the speech product into linear units of performance. However, identifying these pauses requires selecting the relevant interkey intervals (IKI) between production microevents. Different models have been applied to identify such components in the empirical distribution of these delays, in particular Gaussian mixture models (GMM), yet no consensus has emerged regarding the number and interpretation of these components. Here, we analyze IKI distributions from a corpus of keylogs and show that a model with two components is robustly selected across a large range of participants. Furthermore, we show that the contents of these modes are consistent with a fluency vs. disfluency interpretation of the modes by identifying which kinds of events fall into each mode.

The process-disruption hypothesis: how spelling and typing skill affects written composition process and product

This study investigates the possibility that lack of fluency in spelling and/or typing disrupts writing processes in such a way as to cause damage to the substance (content and structure) of the resulting text. 101 children (mean age 11 years 10 months), writing in a relatively shallow orthography (Norwegian), composed argumentative essays using a simple text editor that provided accurate timing for each keystroke. Production fluency was assessed in terms of both within-word and word-initial interkey intervals and pause counts. We also assessed the substantive quality of completed texts. Students also performed tasks in which we recorded time to pressing keyboard keys in response to spoken letter names (a keyboard knowledge measure), response time and interkey intervals when spelling single, spoken words (spelling fluency), and interkey intervals when typing a simple sentence from memory (transcription fluency). Analysis by piecewise structural equation modelling gave clear evidence that all three of these measures predict fluency when composing full text. Students with longer mid-word interkey intervals when composing full text tended to produce texts with slightly weaker theme development. However, we found no other effects of composition fluency measures on measures of the substantive quality of the completed text. Our findings did not, therefore, provide support for the process-disruption hypothesis, at least in the context of upper-primary students writing in a shallow orthography.

Measuring and Assessing Typing Skills in Writing Research

In keyboard writing, typing skills are considered an important prerequisite of proficient text production. We describe the design, implementation, and application of a standardized copy-typing task in order to measure and assess individual typing fluency. A test-retest analysis indicates the instrument’s reliability. While the task has been developed across eleven different languages and the related keyboard layouts, we here refer to a corpus of Dutch copy tasks (n = 1682). Analyses show that copying speed non-linearly varies with age. Bayesian analyses reveal differences in the typing performance and the underlying distributions of inter-key intervals between the different task components (e.g., lexical vs. non-lexical materials; high-frequent vs. lowfrequent bigrams). Based on these findings it is strongly recommended to include copy-task measures in the analysis of keystroke logging data in writing studies. This supports a better comparability and interpretability of keystroke data from more complex or communicatively-embedded writing tasks across individuals. Further potential applications of the copy task for writing research are explained and discussed.

On the cost of unsuccessful searches in search trees with two-way comparisons

Search trees are commonly used to implement access operations to a set of stored keys. If this set is static and the probabilities of membership queries are known in advance, then one can precompute an optimal search tree, namely one that minimizes the expected access cost. For a non-key query, a search tree can determine its approximate location by returning the inter-key interval containing the query. This is in contrast to other dictionary data structures, like hash tables, that only report a failed search. We address the question “what is the additional cost of determining approximate locations for non-key queries”? We prove that for two-way comparison trees this additional cost is at most 1. Our proof is based on a novel probabilistic argument that involves converting a search tree that does not identify non-key queries into a random tree that does.

Influence of virtual keyboard design and usage posture on typing performance and muscle activity during tablet interaction

This study aimed to determine the effects of virtual keyboard designs and postures on task performance and muscle activity during tablet use. Eighteen healthy adults were randomly assigned to one of three postures (DESK, LAP, BED) to complete six sessions of 60-minute typing on a tablet with three virtual keyboards (STD, WIDE, SPLIT) twice in an experimental laboratory. Keystroke dynamics and muscle activity of the forearm and neck-shoulder regions were measured by electromyography. The split virtual keyboard was found to be associated with faster typing speed (SPLIT vs STD, p = .015; SPLIT vs WIDE, p < .001) and decreased muscle activity of extensor digitorum communis (SPLIT vs STD, p = .021). Lap posture was associated with faster typing speed (p = .018) and higher forearm muscle activity (p < .05). Typing performance decreased (p < .001) with elevated neck extensor muscle activity (p = .042) when the task duration prolonged. The split virtual keyboard showed potential to improve tablet ergonomics under various postures. Practitioner Summary: Tablets have become widely used for a variety of tasks and have gradually expanded into the realm of mobile productivity and education. Adequate designs of virtual keyboards for tablets show the potential for increased task performance and decreased muscle activity pertinent to typing activity and posture constraints imposed by non-traditional work positions. Abbreviations: WPM: words per minute; IKI: inter-key press interval; EMG: electromyography; EDC: extensor digitorum communis; FDS: flexor digitorum superficialis; CES: cervical erector spinae; UT: upper trapezius; EA: electrical activity; MVC: maximum voluntary contraction; APDF: amplitude probability distribution function

Testing and Evaluating Typing Ability in Research Writing

Before a person can generate writing that can be deemed respectable when using a keyboard, it is usually acknowledged that they must first have exceptional typing talents. This is because learning to type requires much practice. This is an essential requirement in order to operate a computer keyboard. In this lesson, you will learn how to design a standardized copy-typing task, complete with instructions on how to build, execute, and use the job to evaluate a person's level of expertise in typing. This lesson aims to teach you how to design a standardized copy-typing task so that you can evaluate a person's level of expertise in typing. This lesson will show you how to build a task that can be used to determine a person's degree of experience in typing. This lesson aims to teach you how to design a problem. This is done so that we can analyze and determine the individual's skill level with typing, which is why it is done. This is done as follows: An inquiry into the dependability of the instrument may be carried out by doing an analysis that consists of both an initial test and a subsequent test at some point in time.&#x0D; Even though the task has been validated across eleven different languages and the keyboard layouts are specific to each of those languages, we will use a corpus of Dutch copy tasks with a total of 1682 occurrences. This is because we are going to use a Dutch keyboard layout. This is because we will get a Dutch copy job done on the document. According to the findings of several studies, no link can be characterized as being linear between copying speed and age. Nevertheless, this is something that is the case. A Bayesian investigation concluded that there are variations in typing speed and the underlying inter-key interval distributions that occur across the activity's different facets (e.g., lexical vs. non-lexical materials; high-frequent vs. low-frequent bigrams).&#x0D; The findings here support the argument that writing research should add copy-task metrics to analyzing data received from keyboard recording. This proposal was presented here. This makes it possible to more accurately compare and analyze the keystroke data of persons engaged in writing tasks that are more difficult or communicatively integrated. In the study of writing, there are several other potential applications for the copy assignment; this article delves into each of those potential applications in detail and discusses them.

Age Modulates the Effects of Mental Fatigue on Typewriting.

In the present study, we examined whether age influences the effects of mental fatigue on task performance, and if we could validate the use of measures based on typing behavior as an index of the effects of mental fatigue on different aspects of cognition. Young (N = 24, 18–30 years) and middle-aged (N = 24, 50–67 years) participants performed a typewriting task and a mouse targeting task for 120 min. At the beginning and at the end of the experiment the level of subjective fatigue was assessed. During task performance measures based on typing behavior and EEG were recorded. Results showed that subjective fatigue increased over the experiment in both the young and the middle-aged group. Typing speed decreased with time-on-task (ToT) in both age groups, reflected in larger general interkey intervals and in an increase in typing time. In addition, typing accuracy decreased with ToT in the young group, however, not in the middle-aged group, reflected by an increase in typing errors. Moreover, the young group used the backspace key more often with ToT due to delayed error-correction, reflected in larger backspace sequences, resulting in larger interkey intervals and increased typing time. This effect was absent in the middle-aged group. In the young group, the P3 brain potential amplitude decreased over the experiment, which was related to an increase in typing time, longer general interkey intervals, and an increase in typing errors, suggesting that decreased task engagement was related to less efficient typewriting, at least in the young group. These results indicate that measures based on typing behavior could give information about the process of mental fatigue, and in addition suggest that age influences the effect of mental fatigue on typewriting. More specifically, younger adults more often adopt a strategy that emphasizes speed, while middle-aged adults act more error-aversive than younger adults.

Modeling Basic Writing Processes From Keystroke Logs

AbstractThe goal of this study is to model pauses extracted from writing keystroke logs as a way of characterizing the processes students use in essay composition. Low‐level timing data were modeled, the interkey interval and its subtype, the intraword duration, thought to reflect processes associated with keyboarding skills and composition fluency. Heavy‐tailed probability distributions (lognormal and stable distributions) were fit to individual students' data. Both density functions fit reasonably well, and estimated parameters were found to be robust across prompts designed to assess student proficiency for the same writing purpose. In addition, estimated parameters for both density functions were statistically significantly associated with human essay scores after accounting for total time spent writing the essay, a result consistent with cognitive theory on the role of low‐level processes in writing.

Typing competencies in Alzheimer's disease: An exploration of copy tasks

BackgroundThe diagnostic work-up of Alzheimer Disease (AD) is complex, time-consuming, expensive, and quite demanding for the patients. Therefore, there is a growing need for simple non-invasive tools that add to the diagnostic work-up of patients. ObjectivesThis paper investigates a new method for monitoring motor functions in AD using everyday interactions related to writing with a computer, i.c. executing a copy task. MethodsAn experimental exploratory study was set up in which a carefully designed copy task was presented to three groups of participants: young adults (n = 20), cognitively healthy elderly (n = 20) and age-matched elderly with mild cognitive impairment (MCI) or mild dementia due to AD (n = 12). The task consisted of ten different sub-tasks in which specific bigram characteristics were manipulated. The participants' typing behavior was monitored with keystroke logging. ResultsThe three groups differed significantly from each other in performing the copy task. Typing speed gradually decreased with age. Moreover, the cognitively impaired age-matched adults performed slower on all subtasks expressed in longer interkey intervals within the targeted bigrams. Integrative multilevel modelling showed that all the manipulated bigram characteristics contributed significantly to the model. ConclusionThis explorative study shows the potential relevance of using a typing copy task in the diagnostic work-up of patients with neurodegenerative brain disorders. It relates to a natural task, is non-invasive and easy to automatize. In comparison to other motor tasks it allows for fine-grained measurements at an individual level and combines different aspects of complex and fine motor activities in one task.

Investigation of timing preparation during response initiation and execution using a startling acoustic stimulus.

The purpose of the current study was to examine the processes involved in the preparation of timing during response initiation and execution through the use of a startling acoustic stimulus (SAS). In Experiment 1, participants performed a delayed response task in which a two key-press movement was to be initiated 200ms after an imperative signal (IS) with either a short (200ms) or long (500ms) interval between key-presses. On selected trials, a SAS was presented to probe the preparation processes associated with the initiation delay and execution of the inter-key interval. The SAS resulted in a significant decrease in the initiation time, which was attributed to a speeding of pacemaker pulses used to time the delay interval, caused by an increased activation due to the SAS. Conversely, the SAS delayed the short inter-key interval, which was attributed to temporary interference with cortical processing. In Experiment 2, participants performed a 500-ms delayed response task involving two key-presses 200ms apart. In this condition, the SAS resulted in significantly decreased initiation time and a delayed inter-key interval (p=.053). Collectively, these results support a different timeline for the preparation of the delay interval, which is thought to be prepared in advance of the IS, and the inter-key interval, which is thought to be prepared following the IS. This conclusion provides novel information with regard to timing preparation that is consistent with models in which response preparation, initiation, and execution are considered separate and dissociable processes.

Cascaded processing in written compound word production.

In this study we investigated the intricate interplay between central linguistic processing and peripheral motor processes during typewriting. Participants had to typewrite two-constituent (noun-noun) Finnish compounds in response to picture presentation while their typing behavior was registered. As dependent measures we used writing onset time to assess what processes were completed before writing and inter-key intervals to assess what processes were going on during writing. It was found that writing onset time was determined by whole word frequency rather than constituent frequencies, indicating that compound words are retrieved as whole orthographic units before writing is initiated. In addition, we found that the length of the first syllable also affects writing onset time, indicating that the first syllable is fully prepared before writing commences. The inter-key interval results showed that linguistic planning is not fully ready before writing, but cascades into the motor execution phase. More specifically, inter-key intervals were largest at syllable and morpheme boundaries, supporting the view that additional linguistic planning takes place at these boundaries. Bigram and trigram frequency also affected inter-key intervals with shorter intervals corresponding to higher frequencies. This can be explained by stronger memory traces for frequently co-occurring letter sequences in the motor memory for typewriting. These frequency effects were even larger in the second than in the first constituent, indicating that low-level motor memory starts to become more important during the course of writing compound words. We discuss our results in the light of current models of morphological processing and written word production.

Cognitive processing in new and practiced discrete keying sequences

This study addresses the role of cognitive control in the initiation and execution of familiar and unfamiliar movement sequences. To become familiar with two movement sequences participants first practiced two discrete key press sequences by responding to two fixed series of 6-key specific stimuli. In the ensuing test phase they executed these two familiar and also two unfamiliar keying sequences while there was a two-third chance a tone was presented together with one randomly selected key specific stimulus in each sequence. In the counting condition of the test phase participants counted the low pitched (i.e., target) tones. By and large the results support the dual processor model in which the prime role of the cognitive processor shifts from executing to initiating sequences while the gradual development of motor chunks allows a motor processor to execute the sequences. Yet, the results extend this simple model by suggesting that with little practice sequence execution is based also on some non-cognitive (perhaps associative) learning mechanism and, for some participants, on the use of explicit sequence knowledge. Also, after extensive practice the cognitive processor appears to still contribute to slower responses. The occurrence of long interkey intervals was replicated suggesting that fixed 6-key sequences include several motor chunks. Yet, no indication was found that the cognitive processor is responsible for concatenating these chunks.

Effects of input methods on inter-key press intervals during continuous typing

Two popular input methods for Chinese typing, Microsoft New Phonetic and Boshiamy, were compared in terms of hand and finger loading, key-pressing speed and typing efficiency. Sixteen subjects typed an English and a Chinese text for 30 min each during two test sessions and all keystrokes and their inter-key press intervals were recorded by electronic activity monitoring software. Typing with Microsoft New Phonetic and with Boshiamy was found to have equal hand loadings, but typing with Microsoft New Phonetic was associated with a higher proportion of keystrokes at the number row. The subjects who used Boshiamy typed significantly more words per min than those who used Microsoft New Phonetic, though both groups had similar English typing speeds. The features of requiring fewer keystrokes to build a character and no need to choose matched words among homophones made Boshiamy a more efficient tool, but the risk of musculoskeletal disorders should be studied further. This study examined two input methods for typing Chinese and showed that typing with Boshiamy had a higher efficiency, including a higher proportion of key presses on the home row, required fewer key presses to build characters and resulted in a faster speed than with Microsoft New Phonetic. However, the potential risk of development of upper limb symptoms warrants further study.

Written production of German compounds

In this study, we present an experiment in which we examined the time course of typing German compounds. The compounds varied according to three criteria: (1) whole word frequency (high vs. low), (2) head frequency (high vs. low) and (3) semantic transparency (transparent vs. opaque). In this experiment, we recorded the interkey intervals (IKIs) and concentrated on the IKI measurements found at the boundary of the two immediate constituents in compounds. We refer to this boundary type as an SM-boundary because (S)yllable and (M)orpheme boundaries coincide at this word position. As we found effects of lexical frequency for SM-IKIs in a series of previous studies, we argue that possible differences in SM-IKIs found for compounds of different frequency classes and of different degrees of semantic transparency can give an insight into the processes involved in the written production of German compounds: whole word procedures and/or compositional procedures. Our findings show that SM-IKIs are affected by compound frequency, head frequency and semantic transparency. We therefore argue that both whole word procedures and compositional procedures are involved in the written production of German compounds. These findings are in line with those versions of dual-route models which postulate that the two routes run in parallel and interact.

Processing modes and parallel processors in producing familiar keying sequences.

Recent theorizing indicates that the acquisition of movement sequence skill involves the development of several independent sequence representations at the same time. To examine this for the discrete sequence production task, participants in Experiment 1 produced a highly practiced sequence of six key presses in two conditions that allowed little preparation so that interkey intervals were slowed. Analyses of the distributions of moderately slowed interkey intervals indicated that this slowing was caused by the occasional use of two slower processing modes, that probably rely on independent sequence representations, and by reduced parallel processing in the fastest processing mode. Experiment 2 addressed the role of intention for the fast production of familiar keying sequences. It showed that the participants, who were not aware they were executing familiar sequences in a somewhat different task, had no benefits of prior practice. This suggests that the mechanisms underlying sequencing skills are not automatically activated by mere execution of familiar sequences, and that some form of top-down, intentional control remains necessary.

On the role of the SMA in the discrete sequence production task: a TMS study

Participants practiced two discrete six-key sequences for a total of 420 trials. The 1×6 sequence had a unique order of key presses while the 2×3 sequence involved repetition of a three-key segment. Both sequences showed a long interkey interval halfway the sequence indicating hierarchical sequence control in that not only the 2×3 but also the 1×6 sequence was executed as two successive motor chunks. Besides, the second part of both sequences was executed faster than the first part. This supports the earlier notion of a motor processor executing the elements of familiar motor chunks and a cognitive processor triggering either these motor chunks or individual sequence elements. Low-frequency, off-line transcranial magnetic stimulation (TMS) of the supplementary motor area (SMA) counteracted normal improvement with practice of key presses at all sequence positions. Together, these results are in line with the notion that with moderate practice, the SMA executes short sequence fragments that are concatenated by other brain structures.

The learning of novel finger movement sequences.

1. Experienced typists typed phrases containing words in which one isolated letter was typed with one hand, while the remaining letters were typed with the contralateral hand. 2. The translational and rotational motion of the fingers and wrist of the right hand were obtained optoelectronically from the location of reflective markers placed on the fingers. 3. Midway through the experiment, the key corresponding to the isolated letter was physically switched with another key on the keyboard, and subjects typed the letter in its new location (for 140 trials). The letter "n," typed with the right index finger, was either switched with letters normally typed with the same finger (u), with a different finger but same hand (o), with the same finger of the left hand (v), or with a different finger of the left hand (w). 4. When the words were typed normally, the interkey intervals were relatively short, and the onset of movement of the right hand began before the preceding keypress with the left hand. Thus the movement of the two hands overlapped. Furthermore, the movement to the isolated key was highly stereotypical, with little trial-to-trial variability. 5. After the transposition of keys, there were prolongations in the interkey intervals, with the largest delay occurring directly before the typing of the transposed key. Switches between homologous fingers (involving mirror movements) delayed the onset of keypresses to a lesser extent than did other switches. With practice, these delays were reduced but never reached the control level. 6. After the keyswitch, the onset of movement to the isolated key did not occur on average until after the last keypress with the contralateral hand, except when the switch involved the use of homologous fingers. In the latter case, overlapping movement of the two hands was maintained. Thus the learning of a series of discrete movements does not necessarily require that each movement segment be performed sequentially. 7. After the transposition of keys, the movement pattern and time course to a given key were similar to the movement patterns for that key observed during control trials in all conditions. Thus the learning of a series of movements may involve the use of previously learned movements under new conditions. 8. The results suggest that typing movements may be organized at several levels, including the individual keystroke and word level.

Evidence for the development of concurrent processing in a sequential keypressing task

This paper describes an experiment that aimed at examining the effects of extended practice in a sequential keypressing task. More specifically, predictions of three execution model were tested. First, the classic subprogram-retrieval model (Sternberg et al., 1978) assumes that an action sequence is programmed entirely before sequence execution while later, during sequence execution, instructions for the individual units in the sequence are retrieved. It predicts that keypressing rate decreases with sequence length but specific effects of practice are not predicted. The second mechanism, concurrent processing, assumes that various forms of information processing become increasingly concurrent in the course of practice. More specifically, it is proposed that with practice motor programming and retrieval of individual motor units from a short-term motor buffer concur with actual keypressing which, however, may delay execution of individual actions. Finally, associative motor unitization asserts that sequence execution comes to rely to an increasing degree on the automatic spread of activation among representations of the individual sequence units so that keypressing rate increases with position in the sequence. These and other predictions were verified with a two-choice sequence production task. One sequence contained four, the other two keypresses. The main results are: (a) a reduction with practice of the difference between the times to initiate long and short sequences, (b) practice had a larger effect on final keypresses than on earlier keypresses, and (c) practice had a larger effect on the final keypress of the long than that of the short sequence. An interesting additional effect was the occurrence of a pronounced ‘warming-up’ effect for all interkey intervals at the second and third day of practice. The results were taken as evidence for the development of concurrent programming and concurrent retrieval while little support was observed for associative motor utinization and subprogram-retrieval.