Task difficulty in mental arithmetic affects microsaccadic rates and magnitudes.

Microsaccades are involuntary, small-magnitude saccadic eye movements that occur during attempted visual fixation. Recent research has found that attention can modulate microsaccade dynamics, but few studies have addressed the effects of task difficulty on microsaccade parameters, and those have obtained contradictory results. Further, no study to date has investigated the influence of task difficulty on microsaccade production during the performance of non-visual tasks. Thus, the effects of task difficulty on microsaccades, isolated from sensory modality, remain unclear. Here we investigated the effects of task difficulty on microsaccades during the performance of a non-visual, mental arithmetic task with two levels of complexity. We found that microsaccade rates decreased and microsaccade magnitudes increased with increased task difficulty. We propose that changes in microsaccade rates and magnitudes with task difficulty are mediated by the effects of varying attentional inputs on the rostral superior colliculus activity map.

Programme of the 21st European Conference on Eye Movements.

About ECEM ECEM was initiated by Rudolf Groner (Bern), Dieter Heller (Bayreuth at the time) and Henk Breimer (Tilburg) in the 198 to provide a forum for an interdisciplinary group of scientists interested in eye movements. Since the inaugural meeting in Bern, the conference has been held every two years in different venues across Europe until 2021, when it was planned to take place in Leicester but was cancelled due to the COVID pandemic. It was decided to hold the meeting in Leicester in August 2022 instead, and as an in person meeting rather than an online or hybrid event. Incidentally, the present meeting is the third time the conference has come to the English East Midlands, now in Leicester following previous meetings in the neighbouring cities of Derby and Nottingham. The sites of previous ECEMs and webpages can be found here..

Book of Abstracts of the 21th European Conference on Eye Movements in Leicester 2022.

Contents Keynotes: Iain Gilchrist: Integrative Active Vision p 5 Ziad Hafed: A Vision for orienting in Primate Oculomotor Control Circuitry p 6 Fatema Ghasia: Miniscule Eye Movements Play a Major Role in Binocular Vision Disorders p.7 Miriam Spering: Eye Movements as a Window into Human Decision-Making p.8 Monica S. Castelhano: Explorations of how Scene Context and Previous Experience Dynamically Influence Attention and Eye Movement Guidance p.9   Symposia: Eye Tracking and the Visual Arts p.19 Eye Movements during Text Processing and Multiline Reading p.23 Unstable Fixation and Nystagmus with a Focus on the Next Generation of Researchers p.84 Eye Movements as a measure of Higher-Level Text Processing p.97 Eye Movements in Memory Processes Between Working Memory and Long-Term Memory p.178 Symposium to Honour Alexander Pollatsek's Legacy to Eye Movement Research p.204   Talks: Reading p.30 Parafoveal Processing p.36 Cinical and Applied p.39 Visual Search p.92 Eye Movement Control in Reading I & II p.104 & 116 & 225 Reading Development p.110 Decision-Making p.122 Eye-tracking Methods p.128 Real World and Virtual Reality p.134 Chinese Reading p.185 Special Populations p.191 Visuo-motor p.195 Bilingual Reading p.201 & 217 Reading Comprehension p.219 Pupillometry p.235   Poster sessions: Attention p.44 & 139 Cognition p. 49 Visuo-Motor p.62 Memory p.145 Methods p.150 Reading p. 57 & 155 Real World p.169 Social Cognition p.173.

Eye movements in real and simulated driving and navigation control - Foreword to the Special Issue.

The control of technological systems by human operators has been the object of study for many decades. The increasing complexity in the digital age has made the optimization of the interaction between system and human operator particularly necessary. In the present thematic issue, ten exemplary articles are presented, ranging from observational field studies to experimental work in highly complex navigation simulators. For the human operator, the processes of attention play a crucial role, which are captured in the contributions listed in this thematic issue by eye-tracking devices. For many decades, eye tracking during car driving has been investigated extensively (e.g. 6; 5). In the present special issue, Cvahte Ojstersek & Topolsek (4) provide a literature review and scientometric analysis of 139 eye-tracking studies investigating driver distraction. For future studies, the authors recommend a wider variety of distractor stimuli, a larger number of tested participants, and an increasing interdisciplinarity of researchers. In addition to most studies investigating bottom-up processes of covered attention, Tuhkanen, Pekkanen, Lehtonen & Lappi (10) include the experimental control of top-down processes of overt attention in an active visuomotor steering task. The results indicate a bottom-up process of biasing the optic flow of the stimulus input in interaction with the top-down saccade planning induced by the steering task. An expanding area of technological development involves autonomous driving where actions of the human operator directly interact with the programmed reactions of the vehicle. Autonomous driving requires, however, a broader exploration of the entire visual input and less gaze directed towards the road centre. Schnebelen, Charron & Mars (9) conducted experimental research in this area and concluded that gaze dynamics played the most important role in distinguishing between manual and automated driving. Through a combination of advanced gaze tracking systems with the latest vehicle environment sensors, Bickerdt, Wendland, Geisler, Sonnenberg & Kasneci (2021) conducted a study with 50 participants in a driving simulator and propose a novel way to determine perceptual limits which are applicable to realistic driving scenarios. Eye-Computer-Interaction (ECI) is an interactive method of directly controlling a technological device by means of ocular parameters. In this context, Niu, Gao, Xue, Zhang & Yang (8) conducted two experiments to explore the optimum target size and gaze-triggering dwell time in ECI. Their results have an exemplary application value for future interface design. Aircraft training and pilot selection is commonly performed on simulators. This makes it possible to study human capabilities and their limitation in interaction with the simulated technological system. Based on their methodological developments and experimental results, Vlacic, Knezevic, Mandal, Rodenkov & Vitsas (11) propose a network approach with three target measures describing the individual saccade strategy of the participants in this study. In their analysis of the cognitive load of pilots, Babu, Jeevitha Shree, Prabhakar, Saluja, Pashilkar & Biswas (3) investigated the ocular parameters of 14 pilots in a simulator and during test flights in an aircraft during air to ground attack training. Their results showed that ocular parameters are significantly different in different flying conditions and significantly correlate with altitude gradients during air to ground dive training tasks. In maritime training the use of simulations is per international regulations mandatory. Mao, Hildre & Zhang (7) performed a study of crane lifting and compared novice and expert operators. Similarities and dissimilarities of eye behavior between novice and expert are outlined and discussed. The study of Atik & Arslan (2) involves capturing and analyzing eye movement data of ship officers with sea experience in simulation exercises for assessing competency. Significant differences were found between electronic navigation competencies of expert and novice ship officers. The authors demonstrate that the eye tracking technology is a valuable tool for the assessment of electronic navigation competency. The focus of the study by Atik (1) is the assessment and training of situational awareness of ship officers in naval Bridge Resource Management. The study shows that eye tracking provides the assessor with important novel data in simulator based maritime training, such as focus of attention, which is a decisive factor for the effectiveness of Bridge Resource Management training. The research presented in the different articles of this special thematic issue cover many different areas of application and involve specialists from different fields, but they converge on repeated demonstrations of the usefulness of measuring attentional processes by eye movements or using gaze parameters for controlling complex technological devices. Together, they share the common goal of improving the potential and safety of technology in the digital age by fitting it to human capabilities and limitations.

Introduction to Special Thematic Issue, part 2 "Microsaccades: Empirical Research and Methodological Advances".

Microsaccades are at the interface between basic oculomotor phenomena and complex processes of cognitive functioning, and they also have been a challenge for subtle experimentation and adequate statistical analysis. In the second part of the special thematic issue (for the first part see  4) the authors present a series of articles which demonstrate that microsaccades are still an interesting and rewarding area of scientific research the forefront of research in many areas of sensory, perceptual, and cognitive processes.. In their article "Pupillary and microsaccadic responses to cognitive effort and emotional arousal during complex decision making" Krejtz, Zurawska, Duchowski, & Wichary (1) investigate pupillary and microsaccadic responses to information processing during multi-attribute decision making under affective priming. The participants were randomly assigned into three affective priming conditions (neutral, aversive, and erotic) and instructed to make discriminative decisions. As hypothesized by the authors, the results showed microsaccadic rate inhibition and pupillary dilation, depending on cognitive effort prior to decision and moderated by affective priming. Aversive priming increased pupillary and microsaccadic responses to information processing effort. The results indicate that pupillary response is more influenced by affective priming than microsaccadic rate. The results are discussed in the light of neuropsychological mechanisms of pupillary and microsaccadic behavior. In the article "Microsaccadic rate signatures correlate under monocular and binocular stimulation conditions" Essig, Leube, Rifai, & Wahl (2020) investigate microsaccades with respect to their directional distribution and rate under monocular and binocular conditions. In both stimulation conditions participants fixated a Gabor patch presented randomly in orientation of 45° or 135° over a wide range of spatial frequencies. Microsaccades were mostly horizontally oriented regardless of the spatial frequency of the grating. This outcome was consistent between both stimulation conditions. This study found that the microsaccadic rate signature curve correlates between both stimulation conditions, therefore extending the use of microsaccades to clinical applications, since parameters as contrast sensitivity, have frequently been measured monocularly in the clinical studies. The study "Microsaccades during high speed continuous visual search" by Martin, Davis, Riesenhuber, & Thorpe (3) provides an analysis of the microsaccades occurring during visual search, targeting to small faces pasted either into cluttered background photos or into a simple gray background.  Participants were instructed to target singular 3-degree upright or inverted faces in changing scenes.  As soon as the participant's gaze reached the target face, a new face was displayed in a different random location.  Regardless of the experimental context (e.g. background scene, no background scene), or target eccentricity (from 4 to 20 degrees of visual angle), The authors found that the microsaccade rate dropped to near zero levels within 12 milliseconds.  There were almost never any microsaccades after stimulus onset and before the first saccade to the face. In about 20% of the trials, there was a single microsaccade that occurred almost immediately after the preceding saccade's offset.  The authors argue that a single feedforward pass through the visual hierarchy of processing a stimulus is needed to effectuate prolonged continuous visual search and provide evidence that microsaccades can serve perceptual functions like correcting saccades or effectuating task-oriented goals during continuous visual search. While many studies have characterized the eye movements during visual fixation, including microsaccades, in most cases only horizontal and vertical components have been recorded and analyzed. Little is known about the torsional component of microsaccades. In the study "Torsional component of microsaccades during fixation and quick phases during optokinetic stimulation" Sadeghpour & Otero-Millan (5) recorded eye movements around the three axes of rotation during fixation and torsional optokinetic stimulus. The authors found that the average amplitude of the torsional component of microsaccades during fixation was 0.34 ± 0.07 degrees with velocities following a main sequence with a slope comparable to the horizontal and vertical components. The size of the torsional displacement during microsaccades was correlated with the horizontal but not the vertical component. In the presence of an optokinetic stimulus a nystagmus was induced producing  more frequent and larger torsional quick phases compared to microsaccades produced during fixation of a stationary stimulus. The torsional component and the vertical vergence component of quick phases increased with higher velocities. In previous research, microsaccades have been interpreted as psychophysiological indicators of task load. So far, it is still under debate how different types of task demands are influencing microsaccade rate. In their article "The interplay between task difficulty and microsaccade rate: Evidence for the critical role of visual load" Schneider et al. (6) examined the relation between visual load, mental load and microsaccade rate. The participants carried out a continuous performance task (n-back) in which visual task load (letters vs. abstract figures) and mental task load (1-back to 4-back) were manipulated as within-subjects variables. Eye tracking data, performance data as well as subjective workload were recorded. Data analysis revealed an increased level of microsaccade rate for stimuli of high visual demand (i.e. abstract figures), while mental demand (n-back-level) did not modulate microsaccade rate. The authors concluded that microsaccade rate reflects visual load of a task rather than its mental load. This conclusion is in accordance with the proposition of Krueger et al. (2) "Microsaccades distinguish looking from seeing", linking sensory with cognitive phenomena. The present special thematic issue adds several new interesting facets to the research landscape around microsaccades. They still remain an attractive focus of interdisciplinary research and transdisciplinary applications. Thus, as already noted in the first part of this special thematic issue, research on microsaccades will not only endure, but keep evolving as the knowledge base expands.

Vergence Eye Movements: From Basic Science to Clinical Application - Foreword to the Special Issue.

The abstract book of the last European Conference on Eye Movements [1] lists abstracts of 373 presentations, but less than five percent investigate vergence eye movements, i.e. the coordination of the right and left eye. Why then a special issue on this neglected issue? Human vision under natural conditions involves both eyes in coordination controlled by interacting processes subsumed under the concept of vergence.. Further, vergence is important for people in their daily lives since disorders of vergence can have serious consequences: ophthalmologists deal with squinting patients on the basis of heterophoria and heterotropia testing, eye strain or visual complaints can be related to impaired vergence dynamic or less accurate static vergence, remediation by optometrist includes vergence training or prism eye glasses, etc.

Eye Tracking and Visual Arts. Introduction to the Special Thematic Issue.

There is no visual art without the eye, just like no music without the ear. Visual art does not happen in the eye, but it has to go through the eye. Even for artworks with little visual focus, as in Conceptual Art, we need eyes to create and receive them. In order to see we need to move our eyes. It is therefore not surprising that, for centuries, the eye and its movements have been a major topic of literature on art. It is equally unsurprising that along recent technological improvements of eye tracking, this technology has become prolific for studying visual arts. This special issue of the Journal of Eye Movement Research is the first platform that provides a broad picture of recent developments in this area. In this introduction we present a history of eye movement in art literature, followed by a sketch of some of the oculometric parameters used for studies of visual art. In the third section we showcase each contribution to this special issue.

Microsaccades: Empirical Research and Methodological Advances - Introduction to Part 1 of the Thematic Special Issue.

Recent technical developments and increased affordability of high-speed eye tracking devices have brought microsaccades to the forefront of research in many areas of sensory, perceptual, and cognitive processes. The present thematic issue on "Microsaccades: Empirical Research and Methodological Advances" invited authors to submit original research and reviews encompassing measurements and data analyses in fundamental, translational, and applied studies. We present the first volume of this special issue, comprising 14 articles by research teams around the world. Contributions include the characterization of fixational eye movements and saccadic intrusions in neurological impairments and in visual disease, methodological developments in microsaccade detection, the measurement of fixational eye movements in applied and ecological scenarios, and advances in the current understanding of the relationship between microsaccades and cognition. When fundamental research on microsaccades experienced a renaissance at the turn of the millennium (c.f. 4), one could hardly have been so bold as to predict the manifold applications of research on fixational eye movements in clinic and practice. Through this great variety of areas of focus, some main topics emerge. One such theme is the applicability of microsaccade measures to neurological and visual disease. Whereas microsaccade quantifications have been largely limited to participants with intact visual and oculomotor systems, recent research has extended this interest into the realm of neural and ophthalmic impairment (see 1 for a review). In this volume, Becker et al analyze " Saccadic intrusions in amyotrophic lateral sclerosis (ALS)" and Kang et al study " Fixational eye movement waveforms in amblyopia", delving into the characteristics of fast and slow eye movements. Two other articles focus on how the degradation of visual information, which is relevant to many ophthalmic pathologies, affects microsaccadic features. Tang et al investigate the " Effects of visual blur on microsaccades on visual exploration" and conclude that the precision of an image on the fovea plays an important role in the calibration of microsaccade amplitudes during visual scanning. Otero-Millan et al use different kinds of visual stimuli and viewing tasks in the presence or absence of simulated scotomas, to determine the contributions of foveal and peripheral visual information to microsaccade production. They conclude that " Microsaccade generation requires a foveal anchor". The link between microsaccadic characteristics and cognitive processes has been a mainstay of microsaccade research for almost two decades, since studies in the early 2000s connected microsaccade directions to the spatial location of covert attentional cues (2 3). In the present volume, Dalmaso et al report that " Anticipation of cognitive conflict is reflected in microsaccades", providing new insights about the top-down modulation of microsaccade dynamics. Ryan et al further examine the relationship between " Microsaccades and covert attention" during the performance of a continuous, divided-attention task, and find preliminary evidence that microsaccades track the ongoing allocation of spatial attention. Krueger et al discover that microsaccade rates modulate with visual attention demands and report that " Microsaccades distinguish looking from seeing". Taking the ecological validity of microsaccade investigations one step further, Barnhart et al evaluate microsaccades during the observation of magic tricks and conclude that " Microsaccades reflect the dynamics of misdirected attention in magic". Two articles examine the role of individual differences and intraindividual variability over time on microsaccadic features. In " Reliability and correlates of intra-individual variability in the oculomotor system" Perquin and Bompas find evidence for intra-individual reliability over different time points, while cautioning that its use to classify self-reported individual differences remains unclear. Stafford et al provide a counterpoint in " Can microsaccade rate predict drug response?" by supporting the use of microsaccade occurrence as both a trait measure of individual differences and as a state measure of response to caffeine administration. Methodological and technical advances are the subjects of three papers in this volume. In " Motion tracking of iris features to detect small eye movements" Chaudhary and Pelz describe a new video-based eye tracking methodology that relies on higher-order iris texture features, rather than on lower-order pupil center and corneal reflection features, to detect microsaccades with high confidence. Munz et al present an open source visual analytics system called " VisME: Visual microsaccades explorer" that allows users to interactively vary microsaccade filter parameters and evaluate the resulting effects on microsaccade behavior, with the goal of promoting reproducibility in data analyses. In " What makes a microsaccade? A review of 70 years research prompts a new detection method" Hauperich et al review the microsaccade properties reported between the 1940s and today, and use the stated range of parameters to develop a novel method of microsaccade detection. Lastly, Alexander et al switch the focus from the past of microsaccade research to its future, by discussing the recent and upcoming applications of fixational eye movements to ecologically-valid and real-world scenarios. Their review " Microsaccades in applied environments: real-world applications of fixational eye movement measurements" covers the possibilities and challenges of taking microsaccade measurements out of the lab and into the field. Microsaccades have engaged the interest of scientists from different backgrounds and disciplines for many decades and will certainly continue to do so. One reason for this fascination might be microsaccades' role as a link between basic sensory processes and high-level cognitive phenomena, making them an attractive focus of interdisciplinary research and transdisciplinary applications. Thus, research on microsaccades will not only endure, but keep evolving as the present knowledge base expands. Part 2 of the special issue on microsaccades is already in progress with articles currently under review and will be published in 2021.

The application of eye-tracking in music research.

Though eye-tracking is typically a methodology applied in the visual research domain, recent studies suggest its relevance in the context of music research. There exists a communityof researchers interested in this kind of research from varied disciplinary backgrounds scattered across the globe. Therefore, in August 2017, an international conference was held at the Max Planck Institute for Empirical Aesthetics in Frankfurt, Germany,to bring this research community together. The conference was dedicated to the topic of music and eye-tracking, asking the question: what do eye movements, pupil dilation, and blinking activity tell us about musical processing? This special issue is constituted of top-scoring research from the conference and spans a range of music-related topics. From tracking the gaze of performers in musical trios to basic research on how eye movements are affected by background music, the contents of this special issue highlight a variety of experimental approaches and possible applications of eye-tracking in music research.

Abstracts of the 20th European Conference on Eye Movements, 18-22 August 2019, in Alicante (Spain).

This document contains all abstracts of the 20th European Conference on Eye Movements, August 18-22, 2019, in Alicante, Spain Video stream "Glimpses at 20th ECEM": https://vimeo.com/user43478756.

Microsaccades Distinguish Looking From Seeing.

Understanding our visual world requires both looking and seeing. Dissociation of these processes can result in the phenomenon of inattentional blindness or 'looking without seeing'. Concomitant errors in applied settings can be serious, and even deadly. Current visual data analysis cannot differentiate between just 'looking' and actual processing of visual information, i.e., 'seeing'. Differentiation may be possible through the examination of microsaccades; the involuntary, smallmagnitude saccadic eye movements that occur during processed visual fixation. Recent work has suggested that microsaccades are post-attentional biosignals, potentially modulated by task. Specifically, microsaccade rates decrease with increased mental task demand, and increase with growing visual task difficulty. Such findings imply that there are fundamental differences in microsaccadic activity between visual and nonvisual tasks. To evaluate this proposition, we used a high-speed eye tracker to record participants in looking for differences between two images or, doing mental arithmetic, or both tasks in combination. Results showed that microsaccade rate was significantly increased in conditions that require high visual attention, and decreased in conditions that require less visual attention. The results support microsaccadic rate reflecting visual attention, and level of visual information processing. A measure that reflects to what extent and how an operator is processing visual information represents a critical step for the application of sophisticated visual assessment to real world tasks.

Eye Tracking and Visualization: Introduction to the Special Thematic Issue of the Journal of Eye Movement Research.

There is a growing interest in eye tracking technologies applied to support traditional visualization techniques like diagrams, charts, maps, or plots, either static, animated, or interactive ones. More complex data analyses are required to derive knowledge and meaning from the data. Eye tracking systems serve that purpose in combination with biological and computer vision, cognition, perception, visualization, human-computer-interaction, as well as usability and user experience research. The 10 articles collected in this thematic special issue provide interesting examples how sophisticated methods of data analysis and representation enable researchers to discover and describe fundamental spatio-temporal regularities in the data. The human visual system, supported by appropriate visualization tools, enables the human operator to solve complex tasks, like understanding and interpreting three-dimensional medical images, controlling air traffic by radar displays, supporting instrument flight tasks, or interacting with virtual realities. The development and application of new visualization techniques is of major importance for future technological progress.

[Short-, middle and long-term effects of training in phonological awareness and letter-sound correspondence on phonological awareness and on reading and spelling]. / Kurz-, mittel- und längerfristige Effekte eines Trainings in phonologischer Bewusstheit und in Buchstaben-Laut-Korrespondenz auf die phonologische Bewusstheit und die Lese- und Rechtschreibleistung.

OBJECTIVE: The present study intended to evaluate the short-, middle and long-term effects of preschool training in phonological awareness and letter-sound correspondence, conducted in Swiss dialect in Swiss kindergartens, on the basis of the outcome variables phonological awareness and reading and spelling competence. METHOD: From a total sample of 109 children with complete datasets over all measurement points, a paired sample of 26 children each from the experimental and from the control group was selected for statistical analyses. Evaluated on the one hand were the short- middle and longer-term effects of the training on the development of the phonological awareness, while on the other, the average reading and spelling competencies and the percentage of reading-and-spelling disabled children in the training and in the control group were compared for the 1st and 2nd grades. RESULTS: Effects of the training on phonological awareness could be documented up to the beginning of the 1st grade. The average reading and spelling competencies did not differ be-tween the groups, whereas the percentage of spelling-disabled children was markedly reduced in the training group. CONCLUSIONS: As a whole, the results are seen as a confirmation of the efficacy of the training in the primary prevention of reading and writing disorders.

On the relation between metacontrast masking and suppression of visible persistence.

Does the introduction of additional contours in a display sequence (an operation known to reduce the strength of suppression in metacontrast) also reduce suppression of visible persistence? In three experiments, duration of visible persistence was estimated by a method in which successful performance depends on the temporal integration of a pattern whose elements are displayed in two successive frames. In this procedure, the arrival of the trailing frame is known to exert a suppressive influence on the visible persistence of the leading frame. Embedding the elements of the leading frame within additional contours (a line grid) reduced the degree of suppression exerted by the trailing frame. This did not occur when the grid was part of the trailing display. We conclude that suppression of visible persistence and metacontrast masking belong to the same class of events.

The effect of spatial frequency content on parameters of eye movements.

Two experiments were conducted to examine the influence of the spatial frequency content of natural images on saccadic size and fixation duration. In the first experiment 10 pictures of natural textures were low-pass filtered (0.04-0.76 cycles/deg) and high-pass filtered (1.91-19.56 cycles/deg) and presented with the unfiltered originals in random order, each for 10 s, to 18 participants, with the instruction to inspect them in order to find a suitable name. The participants' eye movements were recorded. It was found that low-pass filtered images resulted in larger saccadic amplitudes compared with high-pass filtered images. A second experiment was conducted with natural stimuli selected for different power spectra which supported the results outlined above. In general, low-spatial frequencies elicit larger saccades associated with shorter fixation durations whereas high-spatial frequencies elicit smaller saccades with longer fixation durations.

Does excessive memory load attenuate activation in the prefrontal cortex? Load-dependent processing in single and dual tasks: functional magnetic resonance imaging study.

Functional magnetic resonance imaging was used to investigate the relationship between cortical activation and memory load in dual tasks. An n-back task at four levels of difficulty was used with auditory-verbal and visual-nonverbal material, performed separately as single tasks and simultaneously as dual tasks. With reference to single tasks, activation in the prefrontal cortex (PFC) commonly increases with incremental memory load, whereas for dual tasks it has been hypothesized previously that activity in the PFC decreases in the face of excessive processing demands, i.e., if the capacity of the working memory's central executive system is exceeded. However, our results show that during both single and dual tasks, prefrontal activation increases continuously as a function of memory load. An increase of prefrontal activation was observed in the dual tasks even though processing demands were excessive in the case of the most difficult condition, as indicated by behavioral accuracy measures. The hypothesis concerning the decrease in prefrontal activation could not be supported and was discussed in terms of motivation factors. Similar changes in load-dependent activation were observed in two other regions outside the PFC, namely in the precentral gyrus and the superior parietal lobule. The results suggest that excessive processing demands in dual tasks are not necessarily accompanied by a diminution in cortical activity.