Brains, it has recently been argued, are essentially prediction machines. They are bundles of cells that support perception and action by constantly attempting to match incoming sensory inputs with top-down expectations or predictions. This is achieved using a hierarchical generative model that aims to minimize prediction error within a bidirectional cascade of cortical processing. Such accounts offer a unifying model of perception and action, illuminate the functional role of attention, and may neatly capture the special contribution of cortical processing to adaptive success. This target article critically examines this "hierarchical prediction machine" approach, concluding that it offers the best clue yet to the shape of a unified science of mind and action. Sections 1 and 2 lay out the key elements and implications of the approach. Section 3 explores a variety of pitfalls and challenges, spanning the evidential, the methodological, and the more properly conceptual. The paper ends (sections 4 and 5) by asking how such approaches might impact our more general vision of mind, experience, and agency.

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Whatever next? Predictive brains, situated agents, and the future of cognitive science

Emotion and Adaptation

The measurement of meaning

Many current neurophysiological, psychophysical, and psychological approaches to vision rest on the idea that when we see, the brain produces an internal representation of the world. The activation of this internal representation is assumed to give rise to the experience of seeing. The problem with this kind of approach is that it leaves unexplained how the existence of such a detailed internal representation might produce visual consciousness. An alternative proposal is made here. We propose that seeing is a way of acting. It is a particular way of exploring the environment. Activity in internal representations does not generate the experience of seeing. The outside world serves as its own, external, representation. The experience of seeing occurs when the organism masters what we call the governing laws of sensorimotor contingency. The advantage of this approach is that it provides a natural and principled way of accounting for visual consciousness, and for the differences in the perceived quality of sensory experience in the different sensory modalities. Several lines of empirical evidence are brought forward in support of the theory, in particular: evidence from experiments in sensorimotor adaptation, visual \"filling in,\" visual stability despite eye movements, change blindness, sensory substitution, and color perception.

A sensorimotor account of vision and visual consciousness-Authors' Response-Acting out our sensory experience

Inhibition and impulsivity: Behavioral and neural basis of response control

The anger-superiority hypothesis states that angry faces are detected more efficiently than friendly faces. Previously research used schematized stimuli, which minimizes perceptual confounds, but violates ecological validity. The authors argue that a confounding of appearance and meaning is unavoidable and even unproblematic if real faces are presented. Four experiments tested carefully controlled photos in a search-asymmetry design. Experiments 1 and 2 revealed more efficient detection of an angry face among happy faces than vice versa. Experiment 3 indicated that the advantage was due to the mouth, but not to the eyes, and Experiment 4, using upright and inverted thatcherized faces, suggests a perceptual basis. The results are in line with a sensory-bias hypothesis that facial expressions evolved to exploit extant capabilities of the visual system.

Search asymmetries with real faces: testing the anger-superiority effect.

Emotion theorists assume certain facial displays to convey information about the expresser's emotional state. In contrast, behavioral ecologists assume them to indicate behavioral intentions or action requests. To test these contrasting positions, over 2,000 online participants were presented with facial expressions and asked what they revealed-feeling states, behavioral intentions, or action requests. The majority of the observers chose feeling states as the message of facial expressions of disgust, fear, sadness, happiness, and surprise, supporting the emotions view. Only the anger display tended to elicit more choices of behavioral intention or action request, partially supporting the behavioral ecology view. The results support the view that facial expressions communicate emotions, with emotions being multicomponential phenomena that comprise feelings, intentions, and wishes.

What do facial expressions convey: feeling states, behavioral intentions, or action requests?

is well-known that eye movements are central to visual perception [1]. Visual acuity decreases dramatically in the periphery of vision, and precise eye movements to specific locations are vital to foveate objects of interest and identify them with high accuracy [1–4]. Given the importance of eye movements for visual perception, there has been a surge of interest in the topic, with numerous studies being conducted to clarify the variables that determine our eye movements (for a historical review see [5]).

In fact, Google Scholar shows that eye movements are discussed in over a million publications, and a Web of Science search reveals 17,000 publications with eye movement in the title or abstract. As shown in Figure 1, the number of publications with eye movement in the title or abstract has also steadily increased over years, culminating in about 200 papers published in 2013.



Figure 1

The number of publications with the “eye movement” in the title or abstract, according to a Web of Science search 2014.



Despite the surge of interest in eye movements, many questions remain unresolved. This is also reflected in this special issue on eye movement control. First, there are a variety of different eye movements [2, 4]. Among the most widely known eye movements are the fast, ballistic saccades (including superfast express saccades) (e.g., B. de Gelder et al., this issue), smooth-pursuit eye movements (J. N. van der Geest et al., this issue), and vergence eye movements (e.g., P. M. Grove et al., this issue) required to fixate objects at different depths. Less well-known and yet intensely researched are microsaccades, tremor, slow drift, and vestibuloocular and optokinetic eye movements that stabilize gaze during motions of the head and motions of large regions of the image on the retina [2, 4].

Secondly and more importantly for the current special issue, eye movements are also controlled by a variety of different factors [1, 4]. Apart from being subject to diverse muscular and ocular constraints, successful voluntary control over eye movements critically depends on the quality of the visual input, which in turn depends on a variety of internal and external factors [1, 6, 7]. The contributions to the present special issue clarify key elements of both internal and external factors in eye movement control (G. W. Alpers et al., U. Ansorge et al., B. de Gelder et al., P. M. Grove et al., D. R. Hardwick et al., W. E. Huddlestone et al., J. Kassubek et al., A. Khan et al., A. Piras et al., N. D. Smith et al., J. N. van der Geest et al., and D. Venini et al., this issue).

In the present contributions, eye movements have also been used to provide new insights into ocular and neurological disorders (J. Kassubek et al., N. D. Smith et al., this issue) and shed new light on the relationship between covert attention and eye movements (e.g., G. W. Alpers et al., U. Ansorge et al., D. R. Hardwick et al., and A. Khan et al., this issue; see also [6–9]). Together, the papers in this special issue provide a timely update on eye movement control that reflects current hot topics in the field, spanning the range from cognitive science over applied psychology to clinical psychology and neuroscience.


Stefanie I. Becker

Gernot Horstmann

Arvid Herwig

Eye Movement Control

Evidence on the coherence between emotion and facial expression in adults from laboratory experiments is reviewed. High coherence has been found in several studies between amusement and smiling; lo...

Coherence between Emotion and Facial Expression: Evidence from Laboratory Experiments:

Three experiments were conducted to investigate whether surprising color singletons capture attention. Participants performed a visual search task in which a target letter had to be detected among distractor letters. Experiments 1 and 2 assessed accuracy as the dependent variable. In Experiment 1, the unannounced presentation of a color singleton 500 ms prior to the letters (and in the same position as the target letter) resulted in better performance than in the preceding conjunction search segment, in which no singleton was presented, and performance was as good in this surprise-singleton trial as in the following feature search segment, in which the singleton always coincided with the target. In contrast, no improvement was observed when the color singleton was presented simultaneously with the letters in Experiment 2, indicating that attentional capture occurred later in the surprise trial than in the feature search segment. In Experiment 3, set size was varied, and reaction time was the dependent variable. Reaction time depended on set size in the conjunction search segment, but not in the surprise trial nor in the feature search segment. The results of the three experiments support the view that surprising color singletons capture attention independently of a corresponding attentional set.

Gernot Horstmann

Papers

Search asymmetries with real faces: testing the anger-superiority effect.

What do facial expressions convey: feeling states, behavioral intentions, or action requests?

Eye Movement Control

Coherence between Emotion and Facial Expression: Evidence from Laboratory Experiments:

Evidence for attentional capture by a surprising color singleton in visual search