“Seeing Rain”: Integrating phenomenological and Bayesian predictive coding approaches to visual hallucinations and self-disturbances (Ichstörungen) in schizophrenia

We present a schizophrenia patient who reports “seeing rain” with attendant somatosensory features which separate him from his surroundings. Because visual/multimodal hallucinations are understudied in schizophrenia, we examine a case history to determine the role of these hallucinations in self-disturbances (Ichstörungen). Developed by the early Heidelberg School, self-disturbances comprise two components: 1. The self experiences its own automatic processing as alien to self in a split-off, “doubled-I.” 2. In “I-paralysis,” the disruption to automatic processing is now outside the self in omnipotent agents. Self-disturbances (as indicated by visual/multimodal hallucinations) involve impairment in the ability to predict moment-to-moment experiences in the ongoing perception-action cycle. The phenomenological approach to subjective experience of self-disturbances complements efforts to model psychosis using the computational framework of hierarchical predictive coding. We conclude that self-disturbances play an adaptive, compensatory role following the uncoupling of perception and action, and possibly, other low-level perceptual anomalies.     

Spilling thoughts: configuring attentional resources in infants’ goal-directed actions

The focus and organization of attention in perception-action coupling is systematically examined in two studies involving 9 and 10 -month-old infants engaged in learning goal-directed behaviors. Experiment 1 (discrimination study) observed the influence of an attentionally demanding motor task on learning and cognition, while Experiment 2 (means-ends study) observed the influence of an attentionally demanding goal on motor planning and reaching performance. Taken together the results of these two experiments revealed that when mental processing resources were directed to thinking about movement, discrimination performance became compromised; conversely, when processing resources were directed to thinking about the goal-state, the motor planning and execution became compromised. These results suggest a “spilling forward” of thoughts onto actions and goal-states and thus an attention-driven cognition/action trade-off for infants’ goal-directed actions. Findings highlight the ultimate importance of emerging motor skills on cognition and are contextualized within the on-going dialogues and developmental debates surrounding perceptual-motor skill development and problem-solving strategies during the first year.     

Non-linear gaining in precision aiming: making Fitts' task a bit easier

The role of information in the processes underlying kinematic trajectory-formation was examined by manipulating the relation between effector space (movement of a hand-held stylus on a graphics tablet) and task space (movement of a cursor on a screen where targets were presented) in a precision aiming task with five different levels of task difficulty. Movement patterns were found to evolve as a function of the flow of information in task space, with participants (N = 13) producing more rapid and more fluent movements when the mapping between spaces included the softening-spring characteristics typical of behavioural patterns at higher levels of task difficulty. We conclude that the kinematic changes (movement time and pattern) observed when task difficulty increases result from informational influences. Information affects behavioural dynamics at the level of the parameters without affecting the underlying dynamical structure.     

The perception of nested affordances: An examination of expert climbers

Nested affordances in climbing comprise of multiple sequential actions, encompassing more than isolated reaching and grasping. This study examined the extent to which the perception of (multiple) nested affordances in climbing can be understood relative to body-scaled anthropometrics (arm span) and action-scaled (maximal action capabilities) measures, in relation to sequential task-goals of varying complexity. The utilisation of functionally equivalent actions during the actualisation of nested affordances was also investigated. Participants were required to estimate the maximal distance a handhold could be reached in four conditions of varying complexity: nested affordances (reach to Touch; reach to Grasp) vs. multiple nested affordances (reach to grasp with one hand followed by Removing the other hand from the starting handhold; reach to grasp with one hand followed by Moving up to another handhold). Ten expert climbers first had to estimate their maximal reaching distance in these different conditions (Touch, Grasp, Remove, Move Up) before performing the climbing movement. This sequence of estimation-action was repeated four times in each condition. Results revealed that action-scaling measures better captured nested affordances when multiple sequential behaviours are nested than body-scaled measures. Our findings also suggest that expert climbers utilise functionally equivalent movements during the realisation of multiple nested affordances (Remove and Move Up conditions).     

Changes in children’s perception-action tuning over short time scales: Bicycling across traffic-filled intersections in a virtual environment

This investigation examined short-term changes in child and adult cyclists’ gap decisions and movement timing in response to general and specific road-crossing experiences. Children (10- and 12-year-olds) and adults rode a bicycle through a virtual environment with 12 intersections. Participants faced continuous cross traffic and waited for gaps they judged were adequate for crossing. In the control condition, participants encountered randomly ordered gaps ranging from 1.5 to 5.0 s at all intersections. In the high-density condition, participants encountered high-density intersections sandwiched between sets of control intersections. These high-density intersections were designed to push participants toward taking tighter gaps. Participants in both conditions were more likely to accept 3.5-, 4.0-, 4.5-, and 5.0-s gaps at the last set of intersections than at the first set of intersections, whereas participants in the high-density condition were also more likely to accept very tight 3.0-s gaps at the last intersections than at the first intersections. Moreover, individuals in the high-density condition who waited less and took shorter gaps at the middle intersections were also more likely to take very tight 3.0-s gaps at the last intersections. The 10-year-olds in both conditions had more time to spare when they cleared the path of the oncoming car at the last intersections, whereas the 12-year-olds and adults showed no change in time to spare across intersections. The discussion focuses on linking short-term change in perceptual-motor functioning to longer term perceptual-motor development.     

Effects of arm weight on C-not-B task performance: implications for the motor inhibitory deficit account of search failures

Toddlers have been found to fail on a three-location search task involving the invisible displacements of an object, namely the C-not-B task. In this task, a child is shown the experimenter's hand that contains a toy. The toy then successively disappears under the three cloths (A, B, then C). The examiner silently releases the toy under the second cloth (B). The hidden object makes a bump in the B cloth that covers it. Young children emit a strong bias toward the last cloth that the experimenter's hand passes under, and this has been labeled the C-not-B error. One possible explanation for toddlers' failures in the C-not-B task is that children lack the motor inhibitory mechanisms. To test this hypothesis, the robustness of the C-not-B error was tested, in a first experiment, against variations in body parameters. By putting additional weights on the arm, the C-not-B error was reduced substantially and the C-not-B task had a higher rate of success. Indeed, in contrast to control participants, who ignored a visual clue indicating the correct location of the hidden object and reached for the last location of the experimenter's hand, the participants with arm weights initiated their reaching movements by using the visual clue. The findings from the second control group indicate that the dramatic increase in successful performance by children with arm weights is not merely a consequence of the focus on the attention to arm movements. The motion of the experimenter's hand in space appears to have made the task difficult because toddlers had no problems inferring that a lump under a cloth indicates the existence of an object without actually having watched an object be hidden there, as demonstrated in a second experiment. The findings are consistent with the hypothesis that C-not-B task content activates a prepotent motor response that preempts full consideration of a visual clue indicating the correct location of the hidden object. We propose that the success in the C-not-B task of toddlers with additional arm weights could result from a disruption of automatic hand movement that is triggered by sensory signals, namely salient features of the C-not-B task.     

Increasing task precision demands reveals that the reach and grasp remain subject to different perception-action constraints in 12-month-old human infants

The reach and grasp follow different developmental trajectories, but are often considered to have achieved nearly adult-like precision and integration by 12 months of age. This study used frame-by-frame video analysis to investigate whether increasing precision demands, by placing small reaching targets on a narrow pedestal rather than on a flat table, would influence the reach and grasp movements of 12-month-old infants in a complementary or differential fashion. The results reveal that placing the target atop a pedestal impaired the infants’s ability to direct an appropriate digit towards the small target, but did not produce a corresponding decrease in the frequency with which they used an index-thumb pincer grip to grasp the target. This was due to the fact that, although infants were more likely to contact the target with a suboptimal part of the hand in the pedestal condition, a greater proportion of these suboptimal contacts ultimately transitioned to a successful index-thumb pincer grip. Thus, increasing task precision demands impaired reach accuracy, but facilitated index-thumb grip formation, in 12-month-old infants. The differential response of the reach and grasp to the increased precision demands of the pedestal condition suggests that the two movements are not fully integrated and, when precision demands are great, remain sensitive to different perception-action constraints in 12-month-old infants.     

When the going gets tough,what happens to quiet eye? The role of time pressure and performance pressure during basketball free throws

In aiming sport contexts, the quiet eye (QE) - the final ocular fixation before movement initiation - is a crucial perceptual-cognitive skill. Indeed, an extended QE permits athletes to achieve high performances, aiding optimal attentional control, particularly in situations in which athletes are "under pressure." Such situations are common in sport, especially when time runs out, and even just a few points can mean the difference between victory and defeat. Although QE has been widely investigated across several sports and tasks, no previous studies have considered both the role of time pressure and performance pressure on QE. The current study aimed to comprehend the effect of tough sport situations on QE characteristics. Accordingly, we tested basketball players (competitive-élites and semi-élites) in free throw trials, manipulating both the time available to perform the task and the relevance of the performance. The results showed that time pressure and performance pressure impaired QE characteristics, regardless of expertise levels. Also, time pressure led to a decrease in free throw accuracy. Interestingly, the match between task demands and the ability to cope seemed to play a role on QE, especially in the competitive-élite players, with negative QE characteristics (short and late) when task demands exceeded the ability to cope. These findings suggest that QE research and QE training protocols should account for time pressure, performance pressure, and the players' perceived ability to cope with the requested task.     

Visual information and body sway coupling in infants during sitting acquisition

The purpose of this study was to examine if there is any developmental change in the coupling between visual information and trunk sway in infants as they acquire the sitting position. Twenty-four infants distributed in four groups (6-, 7-, 8-, and 9-month-old) were sat inside a moving room that oscillated back and forward at frequencies of 0.2 and 0.5 Hz. The results revealed that trunk sway matched to the moving room at both frequencies but did not differ among the four age groups. Coherence and gain revealed that the coupling was weaker at 0.2 than at 0.5 Hz. Relative phase showed that at 0.2 Hz, infants were swaying with no lag but at 0.5 Hz they were lagging the room. These results showed that the coupling between visual information and trunk sway in infants varies with the visual stimulus but does not change as infants acquire the sitting position.     

Sensory information affords exploration of posture in newly walking infants and toddlers

The development of posture and locomotion provides a valuable window for understanding the ontogeny of perception-action relations. In this study, 13 infants were examined cross-sectionally while standing quietly either hands-free or while lightly touching a contact surface. Mean sway amplitude results indicate that infants use light touch for sway attenuation (≈28–40%) as has been seen previously with adults (Jeka & Lackner, 1994). Additionally, while using the contact surface, movement patterns of the head and trunk show reduced temporal coordination (≈25–40%), as well as increased temporal variability, as compared to no touch conditions. These findings are discussed with regard to the ontogeny of perception-action relations, with the overall conclusion that infants use somatosensory information in an exploratory manner to aid in the development of an accurate internal model of upright postural control.