Linked linear mixed models: A joint analysis of fixation locations and fixation durations in natural reading

The complexity of eye-movement control during reading allows measurement of many dependent variables, the most prominent ones being fixation durations and their locations in words. In current practice, either variable may serve as dependent variable or covariate for the other in linear mixed models (LMMs) featuring also psycholinguistic covariates of word recognition and sentence comprehension. Rather than analyzing fixation location and duration with separate LMMs, we propose linking the two according to their sequential dependency. Specifically, we include predicted fixation location (estimated in the first LMM from psycholinguistic covariates) and its associated residual fixation location as covariates in the second, fixation-duration LMM. This linked LMM affords a distinction between direct and indirect effects (mediated through fixation location) of psycholinguistic covariates on fixation durations. Results confirm the robustness of distributed processing in the perceptual span. They also offer a resolution of the paradox of the inverted optimal viewing position (IOVP) effect (i.e., longer fixation durations in the center than at the beginning and end of words) although the opposite (i.e., an OVP effect) is predicted from default assumptions of psycholinguistic processing efficiency: The IOVP effect in fixation durations is due to the residual fixation-location covariate, presumably driven primarily by saccadic error, and the OVP effect (at least the left part of it) is uncovered with the predicted fixation-location covariate, capturing the indirect effects of psycholinguistic covariates. We expect that linked LMMs will be useful for the analysis of other dynamically related multiple outcomes, a conundrum of most psychonomic research.     

Investigating the effects of a set of intercorrelated variables on eye fixation durations in reading

The present experiment investigated the influence of 5 intercorrelated variables on word recognition using a multiple regression analysis. The 5 variables were word frequency, subjective familiarity, word length, concreteness, and age of acquisition (AoA). Target words were embedded in sentences and eye tracking methodology was used to investigate the predictive power of these variables. All 5 variables were found to influence reading time. However, the time course of these variables differed. Both word frequency and familiarity showed an early but lasting influence on eye fixation durations. Word length only significantly predicted fixation durations after refixations on the target words were taken into account. This is the 1st experiment to demonstrate concreteness and AoA effects on eye fixations.     

Tracking the mind during reading: the influence of past, present, and future words on fixation durations

Reading requires the orchestration of visual, attentional, language-related, and oculomotor processing constraints. This study replicates previous effects of frequency, predictability, and length of fixated words on fixation durations in natural reading and demonstrates new effects of these variables related to 144 sentences. Such evidence for distributed processing of words across fixation durations challenges psycholinguistic immediacy-of-processing and eye-mind assumptions. Most of the time the mind processes several words in parallel at different perceptual and cognitive levels. Eye movements can help to unravel these processes.     

The time course of predictability effects in reading: Evidence from a survival analysis of fixation durations

To investigate the time course of predictability effects in reading, the present study examined distributions of first-fixation durations on target words in a low predictability versus a high predictability prior context. In a replication of Staub (2011), ex-Gaussian fitting demonstrated that the low predictability distribution was significantly shifted to the right of the high predictability distribution in the absence of any contextual differences in the degree of skew. Extending this finding, the present study used a survival analysis technique to demonstrate a significant influence of predictability on fixation duration as early as 140 ms from the start of fixation, which is similar to prior results obtained with the word frequency variable. These results provide convergent evidence that lexical variables have a fast acting influence on fixation durations during reading. Implications for models of eye-movement control are discussed.     

Direct lexical control of eye movements in reading: evidence from a survival analysis of fixation durations

Participants' eye movements were monitored in an experiment that manipulated the frequency of target words (high vs. low) as well as their availability for parafoveal processing during fixations on the pre-target word (valid vs. invalid preview). The influence of the word-frequency by preview validity manipulation on the distributions of first fixation duration was examined by using ex-Gaussian fitting as well as a novel survival analysis technique which provided precise estimates of the timing of the first discernible influence of word frequency on first fixation duration. Using this technique, we found a significant influence of word frequency on fixation duration in normal reading (valid preview) as early as 145ms from the start of fixation. We also demonstrated an equally rapid non-lexical influence on first fixation duration as a function of initial landing position (location) on target words. The time-course of frequency effects, but not location effects was strongly influenced by preview validity, demonstrating the crucial role of parafoveal processing in enabling direct lexical control of reading fixation times. Implications for models of eye-movement control are discussed.     

The influence of parafoveal word length and contextual constraint on fixation durations and word skipping in reading

The present study examined the relationship between the predictability of words within a sentence and the availability of parafoveal word length information, on when and where the eyes move in reading. Predictability influenced first-pass reading times when parafoveal word length preview information was correct, but not when it was incorrect. Similarly, for saccades launched from near the target word (wordn), predictability influenced the probability with which it was skipped only when the word length preview was correct. By contrast, for saccades launched farther away from wordn, predictability influenced word skipping regardless of the parafoveal word length preview. Taken together, the data suggest that parafoveal word length preview and predictability can act as a joint constraint on the decision of when and where to move the eyes.     

Early experience of sex hormones as a predictor of reading, phonology, and auditory perception

Previous research has indicated possible reciprocal connections between phonology and reading, and also connections between aspects of auditory perception and reading. The present study investigates these associations further by examining the potential influence of prenatal androgens using measures of digit ratio (the ratio of the lengths of the index and ring fingers). Those with low digit ratios (shorter index finger and therefore in the masculine direction) are hypothesised to have experienced greater "masculinisation" in the uterus. ANCOVA analyses using a verbal reasoning task as a covariate showed that only phonology was influenced by digit ratio in the right hand indicating that hypothesised androgen effects were inhibiting phonology; however this effect in the left hand was reduced and instead there was an effect indicating an inhibition of androgens on reading. Furthermore, subjects with low right-hand digit ratios were also impaired compared to those with high right-hand digit ratios in an auditory saltation task. These findings are discussed in terms of the possible effects of androgens on early brain development impairing aspects of the temporal processing of sounds by the left hemisphere, which could also have a secondary influence on developing phonology and literacy skills.     

Tracking the mind during reading via eye movements: comments on Kliegl, Nuthmann, and Engbert (2006)

R. Kliegl, A. Nuthmann, and R. Engbert reported an impressive set of data analyses dealing with the influence of the prior, present, and next word on the duration of the current eye fixation during reading. They argued that outcomes of their regression analyses indicate that lexical processing is distributed across a number of words during reading. The authors of this comment question their conclusions and address 4 different issues: (a) whether there is evidence for distributed lexical processing, (b) whether so-called parafoveal-on-foveal effects are widespread, (c) the role of correlational analyses in reading research, and (d) problems in their analyses because they use only cases in which words are fixated exactly once.     

Saccade programming during short duration fixations: an examination of copy typing, letter detection, and reading.

Three experiments examined saccade programming during short duration fixations between 50 ms and 150 ms. In experiment 1, subjects copy typed text, in experiment 2, subjects read and executed a letter detection task, and in experiment 3, subjects read for comprehension only. Fixation duration had no effect on the size of the departing saccade in the copy typing task; however, saccades leaving short duration fixations were larger than saccades leaving all other fixation durations in the letter detection task and smaller than saccades leaving long fixation durations in the standard reading task. Within Morrison's (1984) model, these results imply, first, that consecutive shifts of attention during a fixation can take different directions and, second, that successive shifts of attention during a fixation support different purposes. Within Fischer's (1986, in press) model, the results imply that the engagement/disengagement of attention and saccade programming do not constitute independent events.     

Regression analyses as a tool for studying reading processes: Comment on Just and Carpenters eye fixation theory

Just and Carpenter (1980) presented a theory of reading based on eye fixations wherein their “psycholinguistic” variables accounted for 72% of the variance in word gaze durations. This comment raises some statistical and theoretical problems with their use of simultaneous regression analysis of gaze duration measures and with the resulting theory of reading. A major problem was the confounding of perceptual with psycholinguistic factors. New eye fixation data are presented to support these criticisms. Analysis of fixations within words revealed that most gaze duration variance was contributed by number of fixations rather than by fixation duration.     

Sometimes a noun is just a noun: comments on Bird, Howard, and Franklin (2000)

Bird, Howard, and Franklin (2000) have proposed a semantic-conceptual explanation of grammatical category-specific deficits that attributes impairments in noun and verb processing to two distinct mechanisms. According to their account, apparent deficits in verb production are not category specific, but rather result from the lower imageability of verbs compared to concrete nouns. Noun deficits are said to result from differences in the distribution of semantic feature types such that damage to sensory features results in disproportionate impairments in naming nouns, especially animate nouns, compared to verbs. However, this hypothesis, which we call the "extended sensory/functional theory" (ESFT), fails on several counts. First, the assumption that representations of living things are more heavily freighted with sensory features than are those of nonliving objects does not have any reliable empirical basis. Second, the ESFT incorrectly predicts associations between deficits in processing sensory features and living things or functional features and nonliving things. Finally, there are numerous cases of patients with grammatical category-specific deficits that do not seem to be consistent with damage at the semantic level. All of this suggests that the ESFT is not a useful model for considering grammatical (or semantic) category-specific deficits.     

A haphazard reading of McHugh and Barlow (2010)

Replies to comments on Do haphazard reviews provide sound directions for dissemination efforts? (see record 2010-24768-012) by Eileen Gambrill and Julia H. Littell on the current authors' article The dissemination and implementation of evidence-based psychological treatments: A review of current efforts (see record 2010-02208-010) by Kathryn R. McHugh and David H. Barlow. In their commentary, Gambrill and Littell (2010, this issue) suggested that we provided misleading guidance on the selection of treatments for dissemination in our recent article (McHugh & Barlow, February- March 2010) on the dissemination and implementation of evidence-based treatments. These authors misread our article as an affirmation of the evidence base of the treatments involved in the dissemination and implementation efforts we described. In fact, we explicitly disclaimed in the third paragraph that "we do not revisit controversies surrounding the identification or appropriateness of [evidence-based psychological treatments] . . . rather, we focus on the status and adequacy of [dissemination and implementation] efforts currently under way (McHugh & Barlow, 2010, p. 73). Thus, our review was not intended as a guideline for which treatments to disseminate, nor was it a thorough review of the evidence base for the treatments included in the efforts we reviewed. We chose several programs for illustrative purposes as representative efforts from three general domains: national, state, and investigator initiated.     

Early phonological skills as a predictor of reading acquisition: a follow-up study from kindergarten to the middle of grade 2

The purpose of this study was to investigate the power of early measures of phonological skills (phonemic awareness, rapid naming, short-term memory) in predicting later reading skills at various points of time. About 70 children were followed from the end of kindergarten to the middle of grade 2. Correlation analyses were performed as well as a linear growth curve analyses. In the traditional regression analysis, phonemic awareness in kindergarten explained about 27% of the variance in word reading six months later and about 9.5% of the variance at the end of grade 1. Even when prior level of reading skill was included in the predictive equation, a significant amount of variance was still explained by phonemic awareness. The other predictor variables did not explain any variance in word reading, and phonemic awareness did not predict any variance in reading skills in grade 2. When using sentence reading as the dependent variable, phonemic awareness explained about 16% of unique variance after six months, and about 13% of the variance in the middle of grade 2. Similarly, when employing growth curve analysis, phonemic awareness was the only phonological factor that accounted for significant variance in the word reading slope, explaining about 25% of its variance, whereas naming and short-term memory did not explain any unique variance. The lack of predictive power of phonemic awareness on the sentence b-slope is assumed to be caused by unreliable sentence scores in kindergarten.     

Rhythms of dialogue in infancy: comments on Jaffe,Beebe, Feldstein,Crown, and Jasnow (2001)

Analysis of coordinated interpersonal timing has become an important tool for the study of infant-adult, peer, and marital interactions. Past research suggests that social coordination is informative about the quality of the caregiver-child social relationship. Does infant experience of certain types of coordination and pattern in early social interactions with caregivers predict better cognitive and social developmental outcomes? The recent monograph "Rhythms of dialogue in infancy" (Jaffe, Beebe, Feldstein, Crown, & Jasnow, 2001) provides the strongest evidence to date that it does. Moderately coordinated social interactions in early infancy predicted the most favorable developmental outcomes, and degree of coordination was influenced by contextual factors such as setting and nature of the relationship between the infant and its social interaction partner. This study provides a model for future research in this area and points toward important questions for future research on infant-caregiver social interactions.     

Motivation as a predictor of outcomes in school‐based humanistic counselling

Background: Recent years have seen a growth in the provision of counselling within UK secondary schools, and research indicates that it is associated with significant reductions in psychological distress. However, little is known about the moderators and mediators of positive therapeutic benefit. In the field of adult mental health, motivation has been found to be one of the strongest predictors of therapeutic outcomes, and it was hypothesised that this may also be a predictor of outcomes for young people in school‐based counselling services. Aims: To assess the relationship between young people's motivation for counselling and its effectiveness within a secondary school setting. Sample: Eighty‐one young people (12–17 years old) who attended school‐based humanistic counselling services in Scotland. Method: Clients completed a measure of motivation for counselling at the commencement of their therapeutic work and a measure of psychological wellbeing at the commencement and termination of counselling. Results: Motivation for counselling was not found to be significantly related to outcomes. Discussion: The results indicate that the association between motivation and outcomes may be weaker in young people as compared with adults. However, a number of design factors may also account for the non‐significant findings: insufficient participants, marginal reliability of the motivation measure and social desirability effects.     

Hand inversion in sinistrals and lateral preference: Comments on Searleman, Porac, and Coren (1984)

A reanalysis of data from left-handers presented by A. Searleman, C. Porac, and S. Coren, (1984, Brain and Cognition, 3, 86–93) cautions against premature conclusions that an inverted handwriting posture is more prevalent for sinistral men with leftward lateral preferences and for women with rightward or mixed lateral preferences. Although this may eventually prove to be true, the findings of Searleman et al. (1984) are insufficient for supporting this inference.