Cognitive psychology is traditionally interested in the interaction of perception, cognition, and behavioral control. Investigating eye movements in reading constitutes a field of research in which the processes and interactions of these subsystems can be studied in a well-defined environment. Thereby, the following questions are pursued: How much information is visually perceived during a fixation, how is processing achieved and temporally coordinated from visual letter encoding to final sentence comprehension, and how do such processes reflect on behavior such as the control of the eyes’ movements during reading. Various theoretical models have been proposed to account for the specific eye-movement behavior in reading (for a review see Reichle, Rayner, & Pollatsek, 2003). Some models are based on the idea of shifting attention serially from one word to the next within the sentence whereas others propose distributed attention allocating processing resources to more than one word at a time. As attention is assumed to drive word recognition processes one major difference between these models is that word processing must either occur in strict serial order, or that word processing is achieved in parallel. In spite of this crucial difference in the time course of word processing, both model classes perform well on explaining many of the benchmark effects in reading. In fact, there seems to be not much empirical evidence that challenges the models to a point at which their basic assumptions could be falsified. One issue often perceived as being decisive in the debate on serial and parallel word processing is how not-yet-fixated words to the right of fixation affect eye movements. Specifically, evidence is discussed as to what spatial extent such parafoveal words are previewed and how this influences current and subsequent word processing. Four experiments investigated parafoveal processing close to the spatial limits of the perceptual span. The present work aims to go beyond mere existence proofs of previewing words at such spatial distances. Introducing a manipulation that dissociates the sources of long-range preview effects, benefits and costs of parafoveal processing can be investigated in a single analysis and the differing impact is tracked across a three-word target region. In addition, the same manipulation evaluates the role of oculomotor error as the cause of non-local distributed effects. In this respect, the results contribute to a better understanding of the time course of word processing inside the perceptual span and attention allocation during reading. / Die kognitive Psychologie beschäftigt sich traditionell mit dem Zusammenspiel von Wahrnehmung, Kognition und Verhaltenssteuerung. Die Untersuchung von Blickbewegungen beim Lesen bildet dabei ein Forschungsfeld, in dem die Prozesse und Interaktionen dieser Subsysteme in einem klar definierten Rahmen untersucht werden können. Dabei geht es speziell um die Frage, wie viel Information visuell wahrgenommen wird, wie die kognitive Weiterverarbeitung der visuellen Buchstabeninformation über lexikalische Wortverarbeitung hin zu einem inhaltlichen Satzverständnis zeitlich koordiniert ist, und wie sich diese Prozesse auf das Verhalten – die Steuerung der Blickbewegung – auswirken. Verschiedene Modelle zur Erklärung des spezifischen Blickbewegungsverhaltens beim Lesen wurden vorgeschlagen (für einen Überblick siehe Reichle, Rayner, & Pollatsek, 2003). Einige Modelle basieren auf der Annahme serieller Aufmerksamkeitsverschiebung von Wort zu Wort, wohingegen andere verteilte Aufmerksamkeit auf eine Region mehrerer Wörter im Satz gleichzeitig annehmen. Da Aufmerksamkeit eng mit der eigentlichen Wortverarbeitung assoziiert ist, besteht ein wesentlicher Unterschied zwischen den Modellen darin, dass die eigentlichen Wortverarbeitungsprozesse entweder ebenfalls strikt seriell oder parallel erfolgen. Trotz solch entscheidender Unterschiede im zeitlichen Verlauf der Wortverarbeitung können beide Modellklassen viele der Benchmark-Effekte beim Lesen hinreichend erklären. Tatsächlich scheint es nicht viel empirische Evidenz zu geben, die die Grundannahmen der Modelle falsifizieren könnte. Die Frage, ob und wie noch nicht direkt angesehene Wörter rechts der Fixation die Blickbewegung beeinflussen, wird in der Debatte über serielle oder parallele Wortverarbeitung oft als entscheidend betrachtet. Insbesondere wird diskutiert, bis zu welcher Entfernung parafoveale Wörter vorverarbeitet werden und wie das die gegenwärtige und folgende Wortverarbeitung beeinflusst. In einer Serie von vier Leseexperimenten wurde die Vorverarbeitung von Wörtern an den Grenzen der Wahrnehmungsspanne untersucht. Die vorliegende Arbeit versucht zudem, über einen einfachen Existenzbeweis der Vorverarbeitung von Wörtern in solchen Distanzen hinaus zu gehen. Mit einer Manipulation, die verschiedene Quellen solcher weitreichenden Vorverarbeitungseffekte dissoziiert, können Nutzen und Kosten der parafovealen Vorschau in einer einzigen Analyse untersucht und über eine Zielregion von drei Wörtern hinweg verfolgt werden. Dieselbe Manipulation überprüft gleichzeitig die Rolle okulomotorischer Fehler als Ursache für nicht lokale, verteilte Effekte beim Lesen. Die Ergebnisse tragen zu einem differenzierteren Verständnis der Wortverarbeitung in der Wahrnehmungsspanne und der zeitlich-räumlichen Verteilung der Aufmerksamkeit beim Lesen bei.

Using the gaze-contingent boundary paradigm with the boundary placed after word n, we manipulated preview of word n+2 for fixations on word n. There was no preview benefit for first-pass reading on word n+2, replicating the results of Rayner, Juhasz, and Brown (2007), but there was a preview benefit on the three-letter word n+1, that is, after the boundary, but before word n+2. Additionally, both word n+1 and word n+2 exhibited parafoveal-on-foveal effects on word n. Thus, during a fixation on word n and given a short word n+1, some information is extracted from word n+2, supporting the hypothesis of distributed processing in the perceptual span.

Numerous theories have been developed in explanation of object perception, such as Feature Integration Theory, which posits that an object is perceived after two stages: a pre-attentive stage and a focused attention stage. It is during the focused attention stage that a representation of the perceived object is formed. Theories such as object file theory account for the maintenance of these object representations following their creation. Evidence for object file theory has been provided by studies of the object specific preview benefit. This thesis seeks to examine the effect that dividing attention has on the maintenance of object representations. Using the tenets of object file theory and the cortical field hypothesis for dual task interference, it is hypothesized that by presenting participants with two simultaneous tasks which make use of overlapping cortical areas the object representation initially formed will be lost resulting in the loss of the object specific preview benefit. Whereas presenting participants with two simultaneous tasks which are associated with spatially separate, or non-overlapping, cortical regions will not result in the loss of the object specific preview benefit.

This thesis explores the relationship between fixation location and the locus of attention during reading. Early theories of eye movement control during reading suggested that a very tight coupling exists between the two (Just & Carpenter, 1980); however, it has since been shown that dissociations do exist. Whether these dissociations necessarily implicate parallel lexical processing, or whether they can be accommodated for within a serial-sequential framework is explored in a series of experiments. Experiment 1 tested whether parallel lexical processing is, at the very least, psychologically plausible. Two horizontally aligned letter strings were presented simultaneously on a screen, the task being to decide whether they were physically identical or not. Even when presentation duration should have been short enough to prohibit the strictly serial processing of each word in turn, the results show clear lexical effects: high frequency words were responded to faster and with fewer errors than low frequency words. Effects of lexicality and orthography were also found. These results suggest that the two words had been processed at a lexical level in an overlapping fashion. Experiments 2 and 3 investigated the nature and range of word n+2 preview effects. In Experiment 2, word n+1 was either a determiner or 3-letter alternative higher frequency word; in Experiment 3, word n+1 was either a 4- or a 6-letter high frequency word. A gaze contingent display change technique was employed, where prior to passing an invisible boundary located immediately after word n, one, the other, neither or both of words n+1 and n+2 received a nonword preview. In addition to showing orthographic parafoveal-on-foveal effects stemming from word n+1, there was also evidence that word n+2 preview influenced targeting decisions on words n and n+1. Word n+2 preview effects are also found on word n+2 and in the spillover region. These effects were most wide ranging when word n+1 length was an average of 5- compared to 3-letters. Higher-level plausibility preview effects were explored in Experiments 4-6, again using a gaze contingent display change technique. In Experiment 4 word n+1 received either an identical preview, a different but plausible one, or an anomalous, or nonword preview. Critically, an effect of plausibility arose on word n+1, with anomalous previews receiving longer inspection times than alternative plausible previews. Experiments 5 and 6 investigated the range over which these effects might occur, testing for a plausibility preview effect on word n+2. Results showed numerical, but not statistical evidence for a plausibility-related preview effect on word n+2. There were, however, clear orthographic word n+2 preview effects. Finally, Experiment 7 experimentally tested the immediate oculomotor response to a mislocated fixation, using a text shift paradigm to simulate saccadic error and measuring the effect on lexical processing. Critically, this experiment showed that a quick error correction strategy appears to be engaged following a simulated saccadic undershoot, rather than a stay and process response. This suggests that a mislocated fixation account coupled with a stay and process response is unlikely to provide a viable explanation for lexical parafoveal-on-foveal effects. Overall, it is suggested that current instantiations of both serial (e.g., Reichle, Warren & McConnell, 2009) and parallel (e.g., Schad & Engbert, 2012) models of eye movement control during reading appear to fail to capture major aspects of these patterns of results. The results do, however, appear to fit most parsimoniously with a perspective on eye movement control that allows for multiple words to be processed in an overlapping fashion.

Following up on research suggesting an age-related reduction in the rightward extent of the perceptual span during reading (Rayner, Castelhano, & Yang, 2009), we compared old and young adults in an N+2-boundary paradigm in which a nonword preview of word N+2 or word N+2 itself is replaced by the target word once the eyes cross an invisible boundary located after word N. The intermediate word N+1 was always three letters long. Gaze durations on word N+2 were significantly shorter for identical than nonword N+2 preview both for young and for old adults with no significant difference in this preview benefit. Young adults, however, did modulate their gaze duration on word N more strongly than old adults in response to the difficulty of the parafoveal word N+1. Taken together, the results suggest a dissociation of preview benefit and parafoveal-on-foveal effect. Results are discussed in terms of age-related decline in resilience towards distributed processing while simultaneously preserving the ability to integrate parafoveal information into foveal processing. As such, the present results relate to proposals of regulatory compensation strategies older adults use to secure an overall reading speed very similar to that of young adults.

本研究探討中文讀者對於中文雙字詞的早期語意處理，特別要探討的是中文讀者是否能在凝視一個中文雙字複合詞之前，即可提取該詞的語意資訊。在中文的閱讀研究中曾經發現單字的語意資訊可以在該單字被凝視之前提取，不論是成詞的單字或是多字詞其中的組成單字。也有證據顯示中文雙字詞或雙字複合詞呈現在中央視野時的處理方式是整詞處理。由於事實上就詞長來看，雙字詞的詞類數量為中文詞類的最大宗，也是最常被使用的詞類，因此中文雙字詞語意處理的時間歷程便是本研究的研究目標。 　　實驗一旨在檢視雙字詞的語意資訊是否能和單字一樣，在被凝視之前即被提取。本實驗採用邊界典範（Boundary paradigm, Rayner, 1975），除了目標詞預視（identical preview）之外，本實驗亦包含語意相關預視（semantic-related preview）、語意無關預視（semantic-unrelated preview）及非詞預視（nonword preview）。實驗發現語意相關預視能促進目標詞的處理。然而和預視空間（preview space）及預視時間（preview time）的交互作用則顯示語意預視效益（benefit）在預視空間較大的時候會隨著預視時間拉長而增加，在預視空間較小的時候，則會隨著預視時間漸減。 　　在實驗一中，語意關聯性的高低和該詞合理性（plausibility）的高低是共變的，因此這兩個要素構成一個混淆的因子。語意相關預視和語意無關預視之間的效果有可能來自語意關聯性的差異，或是來自在句中合理性的差異。合理性同時也能解釋在為何在實驗一中，不合理的語意無關預視在目標前詞（pretarget）上造成較短的閱讀時間。為了解決這項混淆的因子，實驗二因此採用對目標詞預視、語意相關預視、及語意無關預視都合理的句子。結果發現，語意預視的主要效果消失。然而交互作用的模式則顯示出，語意預視效益在較長的預視時間、較大的預視空間下仍會存在。但在較小的預視空間下，會隨著較長的預視時間而轉為耗損（cost）。實驗二的結果因此提供證據支持在沒有合理性的交互作用下，中文雙字詞的語意預視效應仍會發生。最後，兩個實驗的差異顯示在中文閱讀中存在合理性的預視效益，此結論和之前中文閱讀的研究結果一致。 / The present study investigates the early semantic processing of Chinese two-character words by Chinese readers. Specifically, whether Chinese readers are able to extract semantic information of an up-coming two-character compound as a whole when the word is yet being fixated. In Chinese, it has been demonstrated that semantic information can be extracted from a single character, whether it is a word or part of a word, before the character is being fixated. There is also evidence for whole word processing of foveally presented two-character compounds/words. Since two-character words actually constitute the majority of word type and are used most frequently in total, the time course of processing the meaning of such combination of characters during reading is then the goal of this study. The first experiment aimed to examine whether semantic information of a two-character word can be extracted before it is fixated, as what have been found for single characters. Boundary paradigm (Rayner, 1975) was used, with identical, semantic-related, and semantic-unrelated words, as well as nonwords as preview. Semantic-related preview did facilitate target word processing. The interaction pattern of the effects with preview space and preview time, however, showed that semantic preview benefit could increase with preview time with small preview space, but decrease with preview time under large preview space. A possible confounding factor in the first experiment was the overlap between semantic relatedness and plausibility. The effect between semantic-related and semantic-unrelated previews could be of semantic or plausibility nature. Plausibility may also explain the shortened fixation duration found in Experiment 1 when implausible semantic-unrelated preview was presented parafoveally. Experiment 2 then solved this confounding by using sentence frames which are plausible for identical, semantic-related, and semantic-unrelated previews. In Experiment 2, main effect of semantic preview benefit disappeared, while the interaction patterns showed that such benefit existed for large preview space with long preview time, but became cost for small preview space with long preview time. The results of Experiment 2 thus provide evidence for semantic preview effect of Chinese two-character words without the interaction with plausibility. Finally, the discrepancies between the two experiments indicate the existence of plausibility preview benefit, which previous studies have suggested to exist in Chinese.