Planning and representing intentional action

Active inference as a theory of sentient behavior

This review paper offers an overview of the history and future of active inference-a unifying perspective on action and perception. Active inference is based upon the idea that sentient behavior depends upon our brains' implicit use of internal models to predict, infer, and direct action. Our focus is upon the conceptual roots and development of this theory of (basic) sentience and does not follow a rigid chronological narrative. We trace the evolution from Helmholtzian ideas on unconscious inference, through to a contemporary understanding of action and perception. In doing so, we touch upon related perspectives, the neural underpinnings of active inference, and the opportunities for future development. Key steps in this development include the formulation of predictive coding models and related theories of neuronal message passing, the use of sequential models for planning and policy optimization, and the importance of hierarchical (temporally) deep internal (i.e., generative or world) models. Active inference has been used to account for aspects of anatomy and neurophysiology, to offer theories of psychopathology in terms of aberrant precision control, and to unify extant psychological theories. We anticipate further development in all these areas and note the exciting early work applying active inference beyond neuroscience. This suggests a future not just in biology, but in robotics, machine learning, and artificial intelligence.

Children's socio-moral judgments and behaviors toward peers with and without incarcerated parents

Adults often respond negatively toward children with incarcerated parents. Yet, the developmental foundations for such negativity remain unclear. Two studies (N = 331 U.S. residents; plurality White; plurality male; data collected between Winter 2019 and Spring 2021) addressed this topic. Study 1 probed 5- to 6-year-olds' and 7- to 8-year-olds' inferences about peers with and without incarcerated parents. Children reported less certainty that peers with, versus without, incarcerated parents possess moral beliefs. Study 2 showed that among older children, inferences about parental absence did not fully account for this pattern of results. Across studies, children behaved less generously toward peers with, versus without, incarcerated parents. These studies illuminate how early socio-moral judgment may contribute to negativity toward children with incarcerated parents.

Partial repetition between action plans delays responses to ideomotor compatible stimuli

Often one must depart from an intended course of events to react to sudden situational demands before resuming his or her original action retained in working memory. Retaining an action plan in working memory (WM) can delay or facilitate the execution of an intervening action when the action features of the two action plans partly overlap (partial repetition) compared to when they do not overlap. We investigated whether partial repetition costs (PRCs) or benefits (PRBs) occur when the intervening event is an ideomotor-compatible stimulus that is a biological representation of the response required by the participant. Participants viewed two visual events and retained an action plan to the first event (A) while executing a speeded response to the second, intervening event (B). In Experiment 1A, the two visual events were ideomotor compatible, non-ideomotor compatible (abstract), or one was ideomotor compatible, and the other abstract. Results showed PRCs for all event A-B stimulus combinations with reduced PRCs for intervening, ideomotor compatible events. In contrast to previous research, there was no evidence that ideomotor-compatible actions were automatic and bypassed the selection bottleneck. Experiment 1B confirmed PRCs for ideomotor compatible stimuli that more accurately mimicked the required response. Findings suggest that mechanisms for activating, selecting, and retaining action plans are similar between ideomotor compatible and abstract visual events. We conclude that PRCs occur in response to intervening events when action plans are generated offline and rely on WM, including those for ideomotor-compatible stimuli; but PRBs may be restricted to actions generated online. This conclusion is consistent with the perceptual-motor framework by Goodale and Milner (Trends in Neuroscience 15:22-25, 1992).

Motor expertise modulates unconscious rather than conscious executive control

Background

Executive control, the ability to regulate the execution of a goal-directed task, is an important element in an athlete’s skill set. Although previous studies have shown that executive control in athletes is better than that in non-athletes, those studies were mainly confined to conscious executive control. Many recent studies have suggested that executive control can be triggered by the presentation of visual stimuli without participant’s conscious awareness. However, few studies have examined unconscious executive control in sports. Thus, the present study investigated whether, similar to conscious executive control, unconscious executive control in table tennis athletes is superior to that in non-athletes.

Methods

In total, 42 age-matched undergraduate students were recruited for this study; 22 nonathletic students lacking practical athletic experience comprised one group, and 20 table tennis athletes with many years of training in this sport comprised a second group. Each participant first completed an unconscious response priming task, the unconscious processing of visual-spatial information, and then completed a conscious version of this same response priming task.

Results

Table tennis athletes showed a significant response priming effect, whereas non-athletes did not, when participants were unable to consciously perceive the visual-spatial priming stimuli. In addition, the number of years the table tennis athletes had trained in this sport (a measure of their motor expertise) was positively correlated with the strength of the unconscious response priming effect. However, both table tennis athletes and non-athletes showed a response priming effect when the primes were unmasked and the participants were able to consciously perceive the visual-spatial priming stimuli.

Conclusion

Our results suggest that motor expertise modulates unconscious, rather than conscious, executive control and that motor expertise is positively correlated with unconscious executive control in table tennis athletes.

Action-selection perseveration in young children: Advances of a dynamic model

This study presents an empirical test and dynamic model of perseverative limb selection in children of 14-, 24-, and 36-months old (N = 66 in total). In the experiment, children repeatedly grasped a spoon with a single hand. In two separate conditions, the spoon was presented either four times on their right side or four times on their left side. In both conditions, following this training, the spoon was presented on midline for two more trials. This setup enabled us to determine whether children's limb selection was influenced by their prior choices in the task (i.e., perseveration). Individual children's handedness was determined in a third condition consisting of nine object presentations (laterally or on midline). A dynamic model for limb selection is presented combining external input, motor memory, and preferences. The model was used to simulate the experiment and reproduced the results, including the age-related changes.

Motivational sensitivity of outcome-response priming: Experimental research and theoretical models

Outcome-response (O-R) priming is at the core of various associative theories of human intentional action. This is a simple and parsimonious mechanism by which activation of outcome representations (e.g. thinking about the light coming on) leads to activation of the associated motor patterns required to achieve it (e.g. pushing the light switch). In the current manuscript, we review the evidence for such O-R associative links demonstrated by converging (yet until now, separate) strands of research. While there is a wealth of evidence that both the perceptual and motivational properties of an outcome can be encoded in the O-R association and mediate O-R priming, we critically examine the integration of these mechanisms and the conditions under which motivational factors constrain the sensory O-R priming effect. We discuss the clinical relevance of this O-R priming mechanism, whether it can satisfactorily account for human goal-directed behaviour, and the implications for theories of human action control.

Motor Intention/Intentionality and Associationism - A conceptual review

Motor intention/intentionality (MI) has been investigated from many different angles. Some researchers focus on the purely physical and mechanical aspects of the human motor system, while others emphasize the subjectivity involved in intentionality. While bridging this seemingly dualistic gap between the two concepts ought to be the researcher's' main task, different schools of thought have instead specialized in stressing one (objective) or the other (subjective) part of this construct. Thus, we find everything from neuroscientific to phenomenologically inspired approaches to MI. The purpose of this article is to review the literature regarding these different approaches to the MI construct. In reviewing the literature, we introduce a broadened conception of associationism. In organizing our data in relation to the laws of association, a lack of methodology clearly manifests itself. Hence, 123 articles out of 143 meet the criteria of our definition of associationism. It seems that this old doctrine sneaks in to a big part of the research rather implicitly through a lack of methodology. To shed light on how this happens in the 123 articles, we develop a continuum to show to which extend associationism operates on a transcendent or substantial level in each article. We find only very few articles that seem to try to gap the bridge between motor and intention/intentionality, and thus we suggest that future MI research reintroduce methodological debates concerning the conceptual character of this construct.

Symmetries in action: on the interactive nature of planning constraints for bimanual object manipulation

An important functional question for understanding how people perform physical actions is to understand how they manipulate objects. Previous research suggests that people prefer to move their hands symmetrically. For bimanual object manipulation, such symmetry may take on several forms, however. Actions may be symmetrical when objects are grasped (start symmetry), when they are placed on their target locations (target symmetry), and/or relative to the objects being moved (object symmetry). We studied how these forms of symmetry influenced grasp selection when participants moved two plungers from two start locations to two target locations. We varied the heights of these locations across conditions. The grasp locations participants adopted indicated a preference for object symmetry. This preference was even stronger when initial symmetry coincided with object symmetry. These results provide a tractable illustration of how multiple planning constraints may interact to give rise to both regularity and flexibility in motor behavior.

Body posture modulates action perception

Recent studies have highlighted cognitive and neural similarities between planning and perceiving actions. Given that action planning involves a simulation of potential action plans that depends on the actor's body posture, we reasoned that perceiving actions may also be influenced by one's body posture. Here, we test whether and how this influence occurs by measuring behavioral and cerebral (fMRI) responses in human participants predicting goals of observed actions, while manipulating postural congruency between their own body posture and postures of the observed agents. Behaviorally, predicting action goals is facilitated when the body posture of the observer matches the posture achieved by the observed agent at the end of his action (action's goal posture). Cerebrally, this perceptual postural congruency effect modulates activity in a portion of the left intraparietal sulcus that has previously been shown to be involved in updating neural representations of one's own limb posture during action planning. This intraparietal area showed stronger responses when the goal posture of the observed action did not match the current body posture of the observer. These results add two novel elements to the notion that perceiving actions relies on the same predictive mechanism as planning actions. First, the predictions implemented by this mechanism are based on the current physical configuration of the body. Second, during both action planning and action observation, these predictions pertain to the goal state of the action.

The case of Watson vs. James: effect-priming studies do not support ideomotor theory

In this paper we show that response facilitation in choice reaction tasks achieved by priming the (previously perceived) effect is based on stimulus-response associations rather than on response-effect associations. The reduced key-press response time is not accounted for by earlier established couplings between the key-press movement and its subsequent effect, but instead results from couplings between this effect and the contingent key-release movement. This key-release movement is an intrinsic part of the entire performed response action in each trial of a reaction-time task, and always spontaneously follows the key-press movement. Eliminating the key-release movement from the task leads to the disappearance of the response facilitation, which raises the question whether response-effect associations actually play a role in studies that use the effect-priming paradigm. Together the three experiments presented in the paper cast serious doubts on the claim that action-effect couplings are acquired and utilized by the cognitive system in the service of action selection, and that the priming paradigm by itself can provide convincing evidence for this claim. As a corollary, we question whether the related two-step model for the ideomotor principle holds a satisfying explanation for how anticipation of future states guides action planning. The results presented here may have profound implications for priming studies in other disciplines of psychology as well.

Resolution of outcome-induced response conflict by humans after extended training

Studies of incongruent discrimination learning, where the outcome event of one response acts as the discriminative stimulus for the opposite response, suggest that humans rely on habitual stimulus-response (S-R) associations when outcome-response (O-R) associations would cause response conflict. Here, two experiments were conducted to investigate the robustness of this habitual strategy. In Experiment 1, we found that extensive instrumental discrimination training supported learning about the incongruent R → O contingencies, as assessed by an outcome devaluation test. Differential representations of the stimulus and the (associatively retrieved) outcome may have allowed for goal-directed incongruent performance. Experiment 2 failed to provide evidence for this possibility; direct presentation as well as associative retrieval of the incongruent events (by Pavlovian stimuli) activated the response that was associated with each event in its role of stimulus as opposed to outcome. We did find that participants successfully acquired explicit knowledge of the incongruent contingencies, which raises the possibility that propositional encoding allowed them to overcome the response conflict caused by O-R associations. Alternative associative and propositional accounts of successful goal-directed incongruent performance with extensive training will be discussed.

Understanding motor resonance

The discovery of mirror neurons in monkeys, and the finding of motor activity during action observation in humans are generally regarded to support motor theories of action understanding. These theories take motor resonance to be essential in the understanding of observed actions and the inference of action goals. However, the notions of "resonance," "action understanding," and "action goal" appear to be used ambiguously in the literature. A survey of the literature on mirror neurons and motor resonance yields two different interpretations of the term "resonance," three different interpretations of action understanding, and again three different interpretations of what the goal of an action is. This entails that, unless it is specified what interpretation is used, the meaning of any statement about the relation between these concepts can differ to a great extent. By discussing an experiment we will show that more precise definitions and use of the concepts will allow for better assessments of motor theories of action understanding and hence a more fruitful scientific debate. Lastly, we will provide an example of how the discussed experimental setup could be adapted to test other interpretations of the concepts.

Differential engagement of the ventromedial prefrontal cortex by goal-directed and habitual behavior toward food pictures in humans

According to dual-system accounts, instrumental learning is supported by both a goal-directed and a habitual system. Although behavioral control by the goal-directed system, through outcome-action associations, dominates with moderate training, stimulus-response associations are thought to form concurrently in the habit system. It is therefore challenging to isolate the neural substrate of the goal-directed system in neuroimaging research with healthy human volunteers. Recently, however, de Wit et al. (2007) developed an instrumental discrimination task that distinguishes between goal-directed and habit-based responding. In this task, cues are congruent, unrelated, or incongruent with subsequent outcomes. Whereas performance on congruent and control trials can be supported by both the goal-directed and habitual system, performance on the incongruent discrimination relies solely on the habit system. In the present study, we used this task with healthy participants undergoing functional magnetic resonance imaging to demonstrate that engagement of the goal-directed system during learning is reflected in increased activity in the ventromedial prefrontal cortex. Moreover, using a subsequent outcome devaluation manipulation, we show that this area is involved in guiding decision making when goal values change, even in the absence of external cues to guide performance. We can therefore exclude a purely Pavlovian account of ventromedial prefrontal function and unequivocally demonstrate its involvement in the acquisition as well as deployment of goal-directed knowledge.

Associative theories of goal-directed behaviour: a case for animal-human translational models

Associative accounts of goal-directed action, developed in the fields of human ideomotor action and that of animal learning, can capture cognitive belief-desire psychology of human decision-making. Whereas outcome-response accounts can account for the fact that the thought of a goal can call to mind the action that has previously procured this goal, response-outcome accounts capture decision-making processes that start out with the consideration of possible response alternatives followed only in the second instance by evaluation of their consequences. We argue that while the outcome-response mechanism plays a crucial role in response priming effects, the response-outcome mechanism is particularly important for action selection on the basis of current needs and desires. We therefore develop an integrative account that encapsulates these two routes of action selection within the framework of the associative-cybernetic model. This model has the additional benefit of providing mechanisms for the incentive modulation of goal-directed action and for the development of behavioural autonomy, and therefore provides a promising account of the multi-faceted process of animal as well as human instrumental decision-making.

Special Section: Towards an Embodiment of Goals

This paper discusses both a dissociation view and a dynamic view with respect to the study of voluntary, goal-directed behavior. The dissociation view builds on the recently reintroduced ideomotor principle, and conceives of clearly dissociated and hierarchical roles for the planning and control of action. The dynamic view has a more integral and dynamic conception of how planning, control, and timing merge in the guidance of behavior. This view, however, lacks a clear way of encompassing the goaldirectedness of behavior. For behavior to be effective and efficient, sensory information has to play an equally important role in guiding action as goal-related information does. As a third view, a dynamic action-selection approach is introduced by combining aspects of the former two. This model is able to merge ideomotor and sensorimotor processes continuously and in real time. In discussing the action-selection approach, a special emphasis is given to the role of long-term influences like preferences and goals.

Integration of posture and movement: contributions of Sherrington, Hess, and Bernstein

Neural mechanisms that integrate posture with movement are widespread throughout the central nervous system (CNS), and they are recruited in patterns that are both task- and context-dependent. Scientists from several countries who were born in the 19th century provided essential groundwork for these modern-day concepts. Here, the focus is on three of this group with each selected for a somewhat different reason. Charles Sherrington (1857-1952) had innumerable contributions that were certainly needed in the subsequent study of posture and movement: inhibition as an active coordinative mechanism, the functional anatomy of spinal cord-muscle connectivity, and helping set the stage for modern work on the sensorimotor cortex and the corticospinal tract. Sadly, however, by not championing the work of his trainee and collaborator, Thomas Graham Brown (1882-1965), he delayed progress on two key motor control mechanisms: central programming and pattern generation. Walter Hess (1881-1973), a self-taught experimentalist, is now best known for his work on CNS coordination of autonomic (visceral) and emotional behavior. His contributions to posture and movement, however, were also far-reaching: the coordination of eye movements and integration of goal-directed and "framework" (anticipatory set) motor behavior. Nikolai Bernstein (1896-1966), the quintessence of an interdisciplinary, self-taught movement neuroscientist, made far-reaching contributions that were barely recognized by Western workers prior to the 1960s. Today, he is widely praised for showing that the CNS's hierarchy of control mechanisms for posture and movement is organized hand-in-hand with distributed and parallel processing, with all three subject to evolutionary pressures. He also made important observations, like those of several previous workers, on the goal focus of voluntary movements. The contributions of Sherrington, Hess, and Bernstein are enduring. They prompt thought on the philosophical axioms that appear to have driven their research, and the continual need for emphasis on interdisciplinary, comparative, and transnational approaches to advance movement neuroscience.

Event files: feature binding in and across perception and action

The primate brain codes perceived events in a distributed fashion, which raises the question of how the codes referring to the same event are related to each other. Recent findings suggest that they are integrated into 'object files', episodic bindings of object-related information. However, the problem of integrating distributed codes is not restricted to perception but applies to action planning and sensorimotor processing as well. Here I argue that the brain addresses these problems by creating multi-layered networks of bindings - 'event files' - that temporarily link codes of perceptual events, the current task context, and the actions performed therein. These bindings produce systematic but often surprising and counter-intuitive interactions between, and impairments in, perception and action planning.