Opinion
The (Under)Use of Eye-Tracking in Evolutionary Ecology

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Highlights

  • Sensory ecology has so far focused on the way organisms perceive their environments, but rarely drills down to consider the specific features of the environment that organisms attend to.

  • The speed and accuracy of decision making is central to the success of behavioural strategies in complex environments, so the choice and prioritisation of information is paramount.

  • The unique spatio-temporal resolution of eye-tracking data offers great insight into attentional processing compared with other behavioural measures.

  • Techniques and concepts from experimental psychology offer the potential for novel insights into animal behaviour through the incorporation of attentional sampling and filtering.

  • Eye-tracking approaches have given unique insights into how animals make the goal-directed decisions that represent the substrate of natural selection.

To survive and pass on their genes, animals must perform many tasks that affect their fitness, such as mate-choice, foraging, and predator avoidance. The ability to make rapid decisions is dependent on the information that needs to be sampled from the environment and how it is processed. We highlight the need to consider visual attention within sensory ecology and advocate the use of eye-tracking methods to better understand how animals prioritise the sampling of information from their environments prior to making a goal-directed decision. We consider ways in which eye-tracking can be used to determine how animals work within attentional constraints and how environmental pressures may exploit these limitations.

Section snippets

Eye Tracking for Sensory Ecology

Sensory ecology (see Glossary) studies the ways species sample information from their environment and how they use this information to interact with the world around them. The ability of individuals to locate food, avoid predation (and other hazards), and acquire mate(s) is key to their reproductive success. Each of these activities involves making decisions based on the available sensory information, such as whether a habitat is safe or whether a potential mate is desirable. In the field of

The Importance of (the Limitations of) Attention

Sensory ecologists explicitly acknowledge the substantial interspecific variation in the way in which species acquire (sample) and process (filter and use) sensory information [3,4] (Box 1). At a purely physiological level, this may include differences in the acuity of the various senses due to limitations within the sensory organs themselves. Much of this variation exists because a species will tend to evolve the ability to sample information relevant to their survival [5]. For example, many

Feasibility of Using Eye-Tracking Methodology in Ecology

When using eye-tracking equipment, spatial accuracy (the calibration between the estimated and actual gaze direction) and precision (spread or dispersion) of the recorded raw gaze samples [12] are extremely important considerations, particularly when the visual task includes regions of interest that are separated by a small distance (<8°). Further, the temporal resolution of eye-tracking data can range from 60 to 1250 Hz, with the choice of resolution being dictated by both the temporal

The Present and Future Utility of Eye-Tracking in Evolutionary Ecology

Eye-tracking studies of non-primate animals have been scarce to date, but have already shown potential to provide greater insight into how animals manage to be successful at survival despite relatively limited attentional capabilities. The classic visual-search eye-tracking paradigms employed by experimental psychologists directly lend themselves to understanding how animals search the world during activities such as foraging or maintaining vigilance for predators. However, the uses are by no

Concluding Remarks

Visual attention has an important role to play in ecology and evolution research. It is hoped that adoption of eye-tracking will facilitate the measurement of visual attention to better explain how animals make decisions to optimise fitness. Recent innovations in eye-tracking technology have afforded more opportunities for mobile eye-tracking and measurement of eye-movement in species with eye architecture very different to the human. It is timely that the field of ecology reconsiders the

Acknowledgements

Jac Billington was funded by The Leverhulme Trust during the writing of this article.

Glossary

Area centralis
a small region of the retina which is specialised for high acuity vision. Primates and other mammals have a sophisticated foveated visual system, comprising of the highest density of rods and cones in a higher acuity central region. In the human this high spatial resolution region makes up around 2° of visual angle, with light from the point of fixation falling onto the foveal region.
Attention
a weakly defined phenomenon, whereby limited cognitive resources are directed to a

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