Individual differences in fixation duration distributions in reading

Abstract

The present study investigated the relationship between the location and skew of an individual reader's fixation duration distribution. The ex-Gaussian distribution was fit to eye fixation data from 153 subjects in five experiments, four previously presented and one new. The τ parameter was entirely uncorrelated with the μ and σ parameters; by contrast, there was a modest positive correlation between these parameters for lexical decision and speeded pronunciation response times. The conclusion that, for fixation durations, the degree of skew is uncorrelated with the location of the distribution's central tendency was also confirmed nonparametrically, by examining vincentile plots for subgroups of subjects. Finally, the stability of distributional parameters for a given subject was demonstrated to be relatively high. Taken together with previous findings of selective influence on the μ parameter of the fixation duration distribution, the present results suggest that in reading, the location and the skew of the fixation duration distribution may reflect functionally distinct processes. The authors speculate that the skew parameter may specifically reflect the frequency of processing disruption.

It Takes Time to Prime: Semantic Priming in the Ocular Lexical Decision Task

“…The concentration of the priming effect in the slower tail of the ocular LD distribution suggests that participants were able to flexibly recruit prime information when target resolution was difficult. Although there is no direct evidence that slower trials were associated with more difficult LDs, this interpretation is consistent with previous interpretations of τ-based effects on measures of word recognition as reflecting increased effort White & Staub, 2011; Yap et al., 2012) or a disruption of processing (Staub & Benatar, 2013). In addition, several empirical observations support the notion that the amount of required effort is particularly related to the difficulty of the lexicality decision.…”

“…While different types of distribution models may be suitable for capturing RTs, ex-Gaussian distributions have become increasingly popular within psycholinguistics, showing stable results both within and across experiments (Balota, Yap, Cortese & Watson, 2008;Staub & Benatar, 2013), and have been successfully applied to data obtained using isolated word recognition as well as eye tracking during sentence reading (Staub, White, Drieghe, Hollway & Rayner, 2010;Staub & Benatar, 2013). The exGaussian distribution is a convolution of the Gaussian and exponential distributions and can be described by three parameters (Ratcliff, 1979); μ and σ respectively represent the mean and standard deviation of the Gaussian distribution and τ represents the mean and standard deviation of the exponential distribution, reflecting the degree of skew.…”

Morphology of Primary Visual Cortex Predicts Individual Differences in Fixation Duration during Text Reading

“…Fixation durations average 225 msec across readers, with considerable interindividual variability in this average (Henderson & Luke, in press;Rayner, Li, Williams, Cave, & Well, 2007). Individual differences in fixation duration can provide important data informing basic reading theory (Henderson & Luke, in press;Veldre & Andrews, 2014;Staub & Benatar, 2013;Kuperman & Van Dyke, 2011) and can also provide a behavioral index of reading ability and its change over time (Miller & OʼDonnell, 2013;Blythe & Joseph, 2011). However, despite the importance of individual differences in fixation durations during reading, little is known about the neurocognitive processes that give rise to them.…”

“…The use of fixation duration distributions to explore eye movement control has become an important tool in reading research (Henderson & Luke, in press;Staub & Benatar, 2013;Reingold, Reichle, Glaholt, & Sheridan, 2012;White & Staub, 2012;Staub, White, Drieghe, Hollway, & Rayner, 2010;Rayner et al, 2007;Yang & McConkie, 2001). The ex-Gaussian distribution provides three parameters (Figure 2), mu (μ) capturing central tendency, sigma (σ) capturing variability, and tau (τ) capturing the rightward skew of the distribution.…”

Effect of verbal working memory load during the oculomotor activity in visual search

“…№ 2 щения экспоненциального компонента экспоненциально-гауссовского распределения впра-во. Моделирование распределения длительности фиксаций с помощью экспоненциально-гауссовского распределения получили сегодня определенное распространение (см., напри-мер: Staub, Benatar, 2013). Особый интерес при использовании этого метода представляет анализ параметра , отражающего долю «сверхдлинных фиксаций», связанных с процессами сознательной, фокальной зрительной обработки .…”