Search

This article reports an eye-tracking experiment with 2,500 polymorphemic Dutch compounds presented in isolation for visual lexical decision while readers' eye movements were registered. The authors found evidence that both full forms of compounds (dishwasher) and their constituent morphemes (e.g., dish, washer, er) and morphological families of constituents (sets of compounds with a shared constituent) played a role in compound processing. They observed simultaneous effects of compound frequency, left constituent frequency, and family size early (i.e., before the whole compound has been scanned) and also observed effects of right constituent frequency and family size that emerged after the compound frequency effect. The temporal order of these and other observed effects goes against assumptions of many models of lexical processing. The authors propose specifications for a new multiple-route model of polymorphemic compound processing that is based on time-locked, parallel, and interactive use of all morphological cues as soon as they become even partly available to the visual uptake system. Keywords: morphological structure, lexical processing, eye movements, compounds

In 2 experiments, eye movements were examined during searches in which elements were grouped into four 9-item clusters. The target (a red or blue T) was known in advance, and each cluster contained different numbers of target-color elements. Rather than color composition of a cluster invariantly guiding the order of search though clusters, the use of color was determined by the probability that the target would appear in a cluster of a certain color type: When the target was equally likely to be in any cluster containing the target color, fixations were directed to those clusters approximately equally, but when targets were more likely to appear in clusters with more target-color items, those clusters were likely to be fixated sooner. (The target probabilities guided search without explicit instruction.) Once fixated, the time spent within a cluster depended on the number of target-color elements, consistent with a search of only those elements. Thus, between-cluster search was influenced by global target probabilities signaled by amount of color or color ratios, whereas within-cluster search was directly driven by presence of the target color. Keywords: eye movements, visual search, target color ratio

The authors assessed whether parafoveal perception of emotional content influences saccade programming. In Experiment 1, paired emotional and neutral scenes were presented to parafoveal vision. Participants performed voluntary saccades toward either of the scenes according to an imperative signal (color cue). Saccadic reaction times were faster when the cue pointed toward the emotional picture rather than toward the neutral picture. Experiment 2 replicated these findings with a reflexive saccade task, in which abrupt luminosity changes were used as exogenous saccade cues. In Experiment 3, participants performed vertical reflexive saccades that were orthogonal to the emotional--neutral picture locations. Saccade endpoints and trajectories deviated away from the visual field in which the emotional scenes were presented. Experiment 4 showed that computationally modeled visual saliency does not vary as a function of scene content and that inversion abolishes the rapid orienting toward the emotional scenes. Visual confounds cannot thus explain the results. The authors conclude that early saccade target selection and execution processes are automatically influenced by emotional picture content. This reveals processing of meaningful scene content prior to overt attention to the stimulus. Keywords: attention, emotion, eye movements, scene perception

Media effect studies on children have focused on time spent with media relative to some outcome. We argue that researchers should examine quantity as the sole measure of media input only when it is of theoretical significance. In most circumstances media content and form are more important than time spent. A media diet metaphor is proposed as an alternative approach that includes both amount of exposure and program content across media platforms. Quantity is relevant primarily for hypotheses that concern time displacement (such as TV viewing displacing physical exercise) or other medium-general effects. In addition, technological advances have not yet been exploited that can allow new methodologies for studying media use and impact. As examples, eye tracking and magnetic resonance imaging are discussed to illustrate how new approaches can provide researchers with opportunities to ask different questions and to provide new perspectives on old questions. Keywords: children; media; methodology; television viewing; eye tracking; fMRI

During fixation, the eyes are not still but often exhibit microsaccadic movements. The function of microsaccades is controversial, largely because the neural mechanisms responsible for their generation are unknown. Here, we show that the superior colliculus (SC), a retinotopically organized structure involved in voluntary-saccade target selection, plays a causal role in microsaccade generation. Neurons in the foveal portion of the SC increase their activity before and during microsaccades with sizes of only a few minutes of arc and exhibit selectivity for the direction and amplitude of these movements. Reversible inactivation of these neurons significantly reduces microsaccade rate without otherwise compromising fixation. These results, coupled with computational modeling of SC activity, demonstrate that microsaccades are controlled by the SC and explain the link between microsaccades and visual attention.

Durations of eye fixation were recorded for a numerical Stroop effect experiment. Participants (6 men, 19 women; M age=22 yr.) reported the number of characters present in sequences of variable length (2 to 5 characters) while attempting to ignore the identity of the character. Three conditions were included: congruent (the number of characters and the numeral were matched, e.g., responding 'two' to 22), incongruent (the number of characters and the numeral were mismatched, e.g., responding 'two' to 55), and control (baseline of stimuli made up of 'X's, e.g., responding 'two' to XX). Comparisons among the three conditions produced the longest response times and average durations of fixation for the incongruent condition. The shortest response times and average durations of fixation were obtained for the congruent condition.

To investigate the processing of emotional words by covert attention, threat-related, positive, and neutral word primes were presented parafoveally (2.2[degrees] away from fixation) for 150 ms, under gaze-contingent foveal masking, to prevent eye fixations. The primes were followed by a probe word in a lexical-decision task. In Experiment 1, results showed a parafoveal threat--anxiety superiority: Parafoveal prime threat words facilitated responses to probe threat words for high-anxiety individuals, in comparison with neutral and positive words, and relative to low-anxiety individuals. This reveals an advantage in threat processing by covert attention, without differences in overt attention. However, anxiety was also associated with greater familiarity with threat words, and the parafoveal priming effects were significantly reduced when familiarity was covaried out. To further examine the role of word knowledge, in Experiment 2, vocabulary and word familiarity were equated for low- and high-anxiety groups. In these conditions, the parafoveal threat--anxiety advantage disappeared. This suggests that the enhanced covert-attention effect depends on familiarity with words. Keywords: Anxiety; Attention; Eye movements; Parafoveal; Priming; Threat; Word familiarity.

Four experiments were performed to investigate the contribution of goal-driven modulation in saccadic target selection as a function of time. Observers were required to make an eye movement to a prespecified target that was concurrently presented with multiple nontargets and possibly one distractor. Target and distractor were defined in different dimensions (orientation dimension and colour dimension in Experiment 1), or were both defined in the same dimension (i.e., both defined in the orientation dimension in Experiment 2, or both defined in the colour dimension in Experiments 3 and 4). The identities of target and distractor were switched over conditions. Speed--accuracy functions were computed to examine the flail time course of selection in each condition. There were three major results. First, the ability to exert goal-driven control increased as a function of response latency. Second, this ability depended on the specific target--distractor combination, yet was not a function of whether target and distractor were defined within or across dimensions. Third, goal-driven control was available earlier when target and distractor were dissimilar than when they were similar. It was concluded that the influence of goal-driven control in visual selection is not all or none, but is of a continuous nature. Keywords: Dimensions; Eye movements; Goal-driven control; Time course; Visual selection.

The gaze movements accompanying target localization were examined via human observers and a computational model (target acquisition model [TAM]). Search contexts ranged from fully realistic scenes to toys in a crib to Os and Qs, and manipulations included set size, target eccentricity, and target-distractor similarity, Observers and the model always previewed the same targets and searched identical displays. Behavioral and simulated eye movements were analyzed for acquisition accuracy, efficiency, and target guidance. TAM's behavior generally fell within the behavioral mean's 95% confidence interval for all measures in each experiment/condition. This agreement suggests that a fixed-parameter model using spatiochromatic filters and a simulated retina, when driven by the correct visual routines, can be a good general-purpose predictor of human target acquisition behavior. Keywords: overt visual search, computational models, saccade target selection, population coding, center-of-gravity fixations

The article discusses the development of cultured keratinocytes for the treatment of burns, ocular diseases and gene therapy and how government regulations are curtailing further research. The American regulatory authorities termed the cultured grafts as xenografts since 3T3 mouse cells were used for the multiplication of keratinocytes and raised doubts about the growth of a mouse virus in any leftover irradiated 3T3 cells.

Three eye movement studies with novel lexicons investigated the role of semantic context in spoken word recognition, contrasting 3 models: restrictive access, access-selection, and continuous integration. Actions directed at novel shapes caused changes in motion (e.g., looming, spinning) or state (e.g., color, texture). Across the experiments, novel names for the actions and the shapes varied in frequency, cohort density, and whether the cohorts referred to actions (Experiment 1) or shapes with action-congruent or action-incongruent affordances (Experiments 2 and 3). Experiment 1 demonstrated effects of frequency and cohort competition from both displayed and non-displayed competitors. In Experiment 2, a biasing context induced an increase in anticipatory eye movements to congruent referents and reduced the probability of looks to incongruent cohorts, without the delay predicted by access-selection models. In Experiment 3, context did not reduce competition from non-displayed incompatible neighbors as predicted by restrictive access models. The authors conclude that the results are most consistent with continuous integration models. Keywords: spoken word recognition, artificial lexicons, context integration

The association of increased attention to the more stable internal face features of eyes, nose, and mouth with more accurate face-matching performance is investigated. Unfamiliar face matching is a decision process requiring several seconds to achieve maximum performance is suggested.

Contrasting predictions of serial and parallel views on the processing of foveal and parafoveal information during reading were tested. A high-frequency adjective (young) was followed by either a high-frequency word. (child) or a low-frequency [word.sub.n] (tenor), which in turn was followed by either a correct (performing) or an orthographic illegal [word.sub.n+1] (performing) as a parafoveal preview. A limited parafoveal-on-foveal effect was observed: There were inflated fixation times on [word.sub.n] when the preview of [word.sub.n+1] was orthographically illegal. However, this parafoveal-on-foveal effect was (a) independent of the frequency of [word.sub.n], (b) restricted to those instances when the eyes were very close to [word.sub.n+1], and (c) associated with relatively long prior saccades. These observations are all compatible with a mislocated fixation account in which parafoveal-on-foveal effects result from saccadic undershoots of [word.sub.n+1] and with a serial model of eye movement control during reading.

ABSTRACT. Many animal species use reaching for food to place in the mouth (reach-to-eat) with a hand, and it may be a primitive movement. Although researchers (I. Q. Whishaw, 2005; [...]

ABSTRACT. On the basis of recent observations of a modulation of Fitts's law for manual pointing movements in structured visual arrays (J. J. Adam, R. Mol, J. Pratt, & M. [...]

Individual differences in eye movements during picture viewing were examined across image format, content, and foveal quality in 3 experiments. Experiment 1 demonstrated that an individual's fixation durations were strongly related across 3 types of scene formats and that saccade amplitudes followed the same pattern. In Experiment 2, a similar relationship was observed for fixation durations across faces and scenes, although the amplitude relationship did not hold as strongly. In Experiment 3, the duration and amplitude relationships were observed when foveal information was degraded and even removed. Eye movement characteristics differ across individuals, but there is a great deal of consistency within individuals when viewing different types of images. Keywords: eye movements, individual differences, visual perception cognitive processes Au moyen de trois experiences, les differences individuelles des mouvements oculaires effectues pendant le visionnement d'une image ont ete etudiees en fonction du format de l'image, de son contenu et de la qualite foveale. L'experience 1 a demontre que les durees de fixation etaient fortement liees aux trois types de scenes presentes et qu'il en etait de meme des amplitudes saccadiques. A l'experience 2, on a observe un lien similaire pour ce qui est des durees de fixation des visages et des scenes, mais dans le cas de l'amplitude saccadique, le lien n'etait pas aussi evident. Au cours de l'experience 3, on a observe une relation entre la duree et l'amplitude lorsque l'information foveale etait degradee, voire inexistante. Les caracteristiques du mouvement oculaire sont differentes d'une personne a l'autre, mais, dans le cas du visionnement de differents types d'images, elles presentent des similarites certaines.

The flow of activation from concepts to phonological forms within the word production system was examined in 3 experiments. In Experiment 1, participants named pictures while ignoring superimposed distractor pictures that were semantically related, phonologically related, or unrelated. Eye movements and naming latencies were recorded. The distractor pictures affected the latencies of gaze shifting and vocal naming. The magnitude of the phonological effects increased linearly with latency, excluding lapses of attention as the cause of the effects. In Experiment 2, no distractor effects were obtained when both pictures were named. When pictures with superimposed distractor words were named or the words were read in Experiment 3, the words influenced the latencies of gaze shifting and picture naming, but the pictures yielded no such latency effects in word reading. The picture-word asymmetry was obtained even with equivalent reading and naming latencies. The picture-picture effects suggest that activation spreads continuously from concepts to phonological forms, whereas the picture-word asymmetry indicates that the amount of activation is limited and task dependent. Keywords: attention, cascade processing, eye movements, word production

System identification problems often arise where the only modeling records available consist of multiple short-time-duration signals. This motivates the development of a modeling approach that is tailored for this situation. An identification algorithm is presented here for parameter estimation based on minimizing the simulated prediction error, across multiple signals. The additional complexity of estimating the initial states corresponding to each signal is removed from the estimation algorithm. A numerical simulation demonstrates that the proposed algorithm performs well in comparison to the often-used least squares method (which leads to biased estimates when identifying systems from measurement noise corrupted signals). The approach is applied to the identification of the passive oculomotor plant; parameters are estimated that describe the dynamics of the plant, which represent the time constants of the visco-elastic elements that characterize the plant connective tissue. Index Terms--Initial conditions, oculomotor plant, output error, parameter estimation, state-space.

Eye movements were measured during the performance of a computerized Tower of London task to specify the source of planning abnormalities in patients with 1st-episode schizophrenia or schizoaffective disorder. Subjects viewed 2 arrays of colored balls in the upper and lower parts of the screen. They were asked to plan the shortest sequence of moves required to rearrange the balls in the lower screen to match the upper arrangement. Compared with healthy controls, patients made more planning errors, and decision times were longer. However, the patients showed the same gaze biases as controls prior to making a response, indicating that they understood the requirements of the task, approached the task in a strategic manner by identifying the nature of the problem, and used appropriate fixation strategies to plan and elaborate solutions. The patients showed increased duration of long-gaze periods toward both parts of the screen. This suggests that the patients had difficulty in encoding the essential features of the stimulus array. This finding is compatible with slowing of working memory consolidation. Keywords: schizophrenia, eye movements, Tower of London planning task, cognitive impairments, working memory

The study investigated biases for negative information in component processes of visual attention (initial shift vs. maintenance of gaze) in dysphoric and nondysphoric individuals. Eye movements were recorded while participants viewed a series of picture pairs depicting negative, positive, and neutral scenes (each pair presented for 3 s). Biases in initial orienting were assessed from the direction and latency of the initial shift in gaze, whereas biases in the maintenance of attention were assessed from the duration of gaze on the picture that was initially fixated. Results indicated that the dysphoric group showed a significantly greater bias to maintain gaze longer on negative pictures, relative to control pictures, compared with the nondysphoric group. There was no evidence of a dysphoria-related bias in initial shift of orienting to negative cues. Results are consistent with a depression-related bias that operates in the maintenance of attention on negative material. Keywords: dysphoria, emotional pictures, attentional bias, eye tracking

R. Kliegl, A. Nuthmann, and R. Engbert (2006) 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. Keywords: reading, eye movements, fixation times, models of eye-movement control