Review Article


DOI :10.26650/SP2023-1378279   IUP :10.26650/SP2023-1378279    Full Text (PDF)

Eye Movements and Active Visual Attention Processes

Belgüzar Nilay Türkan

The eye is not just an organ limited by anatomical and physical boundaries but is solely associated with the sense of sight. Since the Renaissance, the eye has been used in art as a symbol of the viewer's imaginative life. It has also played an important role as a material for understanding the human mind. Research on the anatomy and movements of the eye has a long history, spanning a wide geographical range from ancient Greece to the civilisations of Babylon, Mesopotamia, and Egypt. Eye movement is a behaviour shared by all animal species with basic visual structures. The fundamental function of this behaviour is to create a stable representation of the visual world on the retina at any given time and to facilitate exploration of the environment. The study of eye movements provides important insights into how organisms perceive the world by revealing how they look at it. Within the repertoire of human eye movements, saccadic and fixational movements are the most frequently measured and studied in attention literature. The eye-tracking method offers an objective measurement approach for testing previously proposed attention hypotheses and allows the investigation of parameters such as where a person looks at any given moment and for how long. These parameters are particularly important for visual attention studies. Through the window opened by the eyes, cognitive psychology and its different disciplines can explore numerous topics related to human visual attention and, consequently, the mind. In addition to its role in psychology, eye tracking remains an important methodological tool in many fields related to human attention and perception mechanisms, such as art, advertising, and industry. This review briefly covers the origins of the eye-tracking technique, followed by the basic mechanics of eye movements. Finally, the study discusses the relationship between eye movements and attentional processes, which are essential for various mental tasks. 

DOI :10.26650/SP2023-1378279   IUP :10.26650/SP2023-1378279    Full Text (PDF)

Göz Hareketleri ve Aktif Görsel Dikkat Süreçleri

Belgüzar Nilay Türkan

Göz, anatomik ve fiziksel sınırları içinde sadece görme duyusundan ibaret bir organ değildir. Resim sanatında Rönesans’tan bu yana bakışın, bakanın imgesel hayatına gönderme yapan bir sembol olarak göz, bilim insanlarının zihni anlamak için kullandığı önemli bir malzeme niteliğindedir. Gözün anatomisi ve hareketleri üzerine yapılan araştırmalar, antik Yunan'dan Babil, Mezopotamya ve Mısır uygarlıklarına kadar uzanan geniş bir coğrafyada, oldukça köklü bir geçmişe sahiptir. Göz hareketleri insan gibi temel görme yapılarına sahip olan tüm hayvan türleri ile ortak sahip olduğumuz bir davranıştır. Bu davranışın temel işlevi, belirli bir anda görsel dünyanın retinada sabit bir temsilini oluşturmak ve ardından çevrenin keşfedilmesini sağlamaktır. Göz hareketlerini incelemek, organizmanın dünyaya nasıl baktığıyla ilgili bilgi vererek dünyayı nasıl algıladığı konusunda önemli ipuçları sağlamaktadır. İnsanın göz hareketleri repertuvarı arasından sıçrama ve odaklama türü hareketler alan yazında en sık ölçülen ve dikkat ile ilişkisi çalışılan hareketlerdir. Özellikle daha önce ortaya atılmış olan dikkat hipotezlerinin test edilmesinde objektif bir ölçüm yöntemi sunan göz izleme yöntemi ile bir kişinin belirli bir anda nereye, ne kadar süreyle baktığı gibi parametreler incelenebilmektedir. Bu parametreler özellikle görsel dikkat çalışmaları için önemli ölçüm ve analiz imkanı sağlamaktadır. Bilişsel Psikoloji ve psikolojinin farklı disiplinleri gözler aracılığıyla açılan pencereden, insan görsel dikkati ve dolayısıyla zihnine dair pek çok konuyu araştırabilmektedir. Psikoloji disiplinindeki rolüne ek olarak, göz izleme yöntemi, sanat, reklamcılık ve endüstri gibi insanların dikkat ve algı mekanizmaları ile ilişkili birçok alanda önemli bir yöntemsel araç olmaya devam etmektedir. Bu derleme yazısında kısaca göz izleme yönteminin tarihçesi, ardından temel göz hareketleri sistematiği ve son olarak da göz hareketleri ile çeşitli zihinsel görevler için gerekli olan dikkat süreçleri arasındaki ilişkiler ele alınmaktadır. 


EXTENDED ABSTRACT


The human eye is not merely a physical organ responsible for vision; it has also held symbolic significance in art, representing the imaginative life of the beholder since the Renaissance. Moreover, it is a valuable tool for comprehending the human mind, with a rich history of anatomical and movement-related research dating back to ancient civilizations (Belting, 2020). Across all species with visual structures, eye movements are a shared behaviour that plays a pivotal role in creating a stable visual representation on the retina and facilitating environmental exploration. The primary function of eye movements can be summarized as maintaining a constant image on the retina in the face of a dynamically changing visual environment, enabling a stable and meaningful representation of the observed surroundings, and allowing for detailed information acquisition (Fooken et al., 2021).

Eye-tracking technology has become a valuable tool for objectively measuring attention, allowing researchers to investigate where and how long a person looks at specific points. In the early 20th century, objective applications replaced the original observation-based methods of studying eye movements (Wade, 2010). These earlier methods involved invasive techniques that required direct contact with the eyes, usually while the participant was performing a reading task. Today, non-invasive devices with sampling rates ranging from 60 to 2000 Hz offer a reliable approach across various psychological research domains, particularly relevant in the study of visual attention. This technology provides valuable insights into how humans perceive their surroundings, making it a beneficial asset for cognitive psychology as it delves into subjects related to visual attention and the human mind. Furthermore, eye tracking is crucial in psychological research and other fields, such as art, advertising, and industry.

When individuals decide to allocate their overt attention to a particular object, they often perform a saccadic eye movement to bring that object into their central, high-resolution vision area, known as the fovea. Depending on our head-body movements or the movements of objects in the environment, various eye movements have the function of directing the fovea to the region of interest. Among these movements, vestibular-ocular reflex (VOR) and optokinetic nystagmus (ON) have a more reflexive nature (Distler & Hoffmann, 2011; Hess, 2011). The most typical example of ON movement in daily life is following a view through the window of a moving train with eye movements. VOR, on the other hand, is a result of the coordination between the sense of balance and the oculomotor system (Hess, 2011). Moreover, when a viewer is in motion while observing a moving object, the eye movement that allows the fovea to maintain the center of interest is called smooth pursuit (Dodge, 1903). 

Among the various eye movements, saccades and fixations are frequently studied in the context of overt attention mechanisms. When individuals remain stationary while observing an unchanging image, they tend to generate saccadic and fixational eye movements (Gilchrist, 2011; Rayner, 2009). Consequently, the saccade-fixate repertoire is one of the most extensively studied aspects of human eye movements (Foulsham, 2019). Saccades, characterized by their rapid and ballistic nature, efficiently redirect gaze from one point to another. Their primary function is to position the eye so that the fovea can scrutinize a new target (Buswell, 1935; Henderson et al., 2003; Rayner, 2009). Fixations, however, are brief pauses during which the eye remains "relatively" still and allow attentive visual information processing at the fixation point (Findlay & Gilchrist, 2003). Fixations facilitate in-depth analysis of visual information within the attended area. Thus, the dynamic interplay between saccades and fixations is essential for humans to gain knowledge and make sense of the world through eye movements.

Saccades are the most frequently occurring eye movements throughout the day, occurring approximately three to four times per second. When obtaining detailed information from a scene between a series of saccades, we refer to eye movements that last between 50 and 600 ms as fixations (Findlay & Gilchrist, 2003). Fixations have a significant function in accomplishing cognitive tasks, and their fundamental characteristics vary depending on the nature of the task at hand (Rayner, 1998). Rayner (2009) observed that viewers typically made fixations lasting approximately 225-325 ms during reading tasks, often accompanied by saccades within one to two degrees. Conversely, fixations typically last between 180 and 330 ms during scene perception or visual search tasks, with corresponding saccades occurring within three to five degrees.

During fixations, the eyes remain "relatively" fixed, signifying that the eye is never entirely stationary but exhibits greater stability than other eye movements. Within fixations, continuous subtle movements occur, both vertically and horizontally. These are referred to as fixational eye movements and include microsaccades, drifts, and tremors (Kowler, 2011). The most popular explanation for the function of these micro eye movements, which increase during focusing, is that they maintain the perceived visual information and detailed information from the scene (Martinez-Conde et al., 2006). Moreover, these movements prevent neural adaptation of the nerve cells in the retina, ensuring that they continue firing and thereby preventing perceptual fading of the visual input (Martinez-Conde et al., 2004).

Attention can be executed without eye movements; however, with attention, it is possible to plan and initiate eye movements (Liversedge & Findlay, 2000). Covert attention and mental processes can be carried out even without explicit and measurable eye movements, especially in a stimulus-rich visual environment, to select some of the stimuli to be directed to the fovea, which is the area of sharp vision, and to determine the future of the movement. The timing, location, and duration of eye movements were systematically analyzed to provide an objective behavioural representation of overt attention. Overt attention refers to the conscious and selective allocation of attention to particular areas or objects in the visual field. The relationship between eye movements and overt attentional mechanisms is pivotal to understanding how humans engage with their visual surroundings. 

When individuals are presented with a complex visual scene, several factors come into play that influence their eye movements. These factors encompass both top-down and bottom-up information processing. The spatial and temporal allocation of attention involves top-down processing, such as the goal of an observer, the task at hand, and individual differences. For instance, in a visual search task, eye movements may be driven by the goal of locating a specific target, whereas during a reading task, eye movements are closely linked to word processing. Additionally, contextual cues, such as the presence of salient objects or the spatial arrangement of a visual scene, can also influence the timing and location of eye movements.

Given that our eyes can focus on only one location at a time, determining where the viewer initially gazes can be regarded as a parameter of selective visual attention, while the examination of where the eyes fixate and for how long constitutes a parameter of focused attention (Deubel & Schneider, 1996). The analysis of eye movement direction and regions of interest provides valuable insights into the trajectory of attention. Examining the sequence and location of eye movements helps to understand the scan path of these movements (Noton & Stark, 1971). Eye movement patterns are often compared to investigate how different types of stimuli affect attention, explore individual differences, examine visual attention and perception processes between experts and non-experts in a given field, identify biological markers in clinical groups, and evaluate critical cues in social interactions.

In addition to the spatial aspects of eye movements, the temporal dynamics of eye movements represent another critical facet for understanding attention mechanisms. Among the time-related parameters of eye movements, the first fixation latency is often used to measure how quickly attention shifts toward a stimulus. This is commonly referred to as the attentional attraction hypothesis. On the other hand, fixation duration is typically used to measure the duration for which attention remains fixed on a specific location or stimulus, thus embodying the attentional disengagement hypothesis (Henderson & Hollingworth, 2000). Although the average duration of fixations, typically around 300 ms, varies depending on factors like the intention of an observer, stimulus characteristics, and individual differences, people often exhibit shorter, more exploratory eye movements when initially encountering a scene (Foulsham, 2019; Rayner, 2009). Conversely, individuals trying to recall a scene or object tend to direct their gaze longer (Foulsham, 2015). 

In summary, the relationship between the timing of eye movements and the allocation of overt attention to specific objects or regions within the visual field represents a multifaceted interplay. Various factors influence this relationship, including the nature of the visual scene, task demands, and individual differences. This review article provides robust results on eye movements and attention mechanisms, tracing the historical evolution of eye-tracking techniques, categorizing fundamental eye movements through human research, and elucidating the pivotal relationship between eye movements and attention processes, which underpin all cognitive activities. The relationship between eye movements and attention is described according to the temporal and spatial basis of cognitive performance. Additionally, apart from the explicit eye movements discussed in this review, it is argued that individuals can direct their attention to specific regions through implicit attention (Liversedge & Findlay, 2000); hence, more studies should be conducted on eye movement parameters associated with implicit attention mechanisms in the future. Furthermore, it is anticipated that the external validity of these studies will expand with the integration of virtual reality and artificial intelligence-based methods into eye movements and attention research.


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APA

Türkan, B.N. (2024). Eye Movements and Active Visual Attention Processes. Studies in Psychology, 44(2), 144-178. https://doi.org/10.26650/SP2023-1378279


AMA

Türkan B N. Eye Movements and Active Visual Attention Processes. Studies in Psychology. 2024;44(2):144-178. https://doi.org/10.26650/SP2023-1378279


ABNT

Türkan, B.N. Eye Movements and Active Visual Attention Processes. Studies in Psychology, [Publisher Location], v. 44, n. 2, p. 144-178, 2024.


Chicago: Author-Date Style

Türkan, Belgüzar Nilay,. 2024. “Eye Movements and Active Visual Attention Processes.” Studies in Psychology 44, no. 2: 144-178. https://doi.org/10.26650/SP2023-1378279


Chicago: Humanities Style

Türkan, Belgüzar Nilay,. Eye Movements and Active Visual Attention Processes.” Studies in Psychology 44, no. 2 (Nov. 2024): 144-178. https://doi.org/10.26650/SP2023-1378279


Harvard: Australian Style

Türkan, BN 2024, 'Eye Movements and Active Visual Attention Processes', Studies in Psychology, vol. 44, no. 2, pp. 144-178, viewed 2 Nov. 2024, https://doi.org/10.26650/SP2023-1378279


Harvard: Author-Date Style

Türkan, B.N. (2024) ‘Eye Movements and Active Visual Attention Processes’, Studies in Psychology, 44(2), pp. 144-178. https://doi.org/10.26650/SP2023-1378279 (2 Nov. 2024).


MLA

Türkan, Belgüzar Nilay,. Eye Movements and Active Visual Attention Processes.” Studies in Psychology, vol. 44, no. 2, 2024, pp. 144-178. [Database Container], https://doi.org/10.26650/SP2023-1378279


Vancouver

Türkan BN. Eye Movements and Active Visual Attention Processes. Studies in Psychology [Internet]. 2 Nov. 2024 [cited 2 Nov. 2024];44(2):144-178. Available from: https://doi.org/10.26650/SP2023-1378279 doi: 10.26650/SP2023-1378279


ISNAD

Türkan, BelgüzarNilay. Eye Movements and Active Visual Attention Processes”. Studies in Psychology 44/2 (Nov. 2024): 144-178. https://doi.org/10.26650/SP2023-1378279



TIMELINE


Submitted19.10.2023
Accepted04.04.2024
Published Online14.08.2024

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