Atypical maternal behavior toward feeding‐disordered infants before and after intervention

The display of atypical behaviors and disrupted communication during parent–infant interactions, as assessed by the Atypical Maternal Behavior Instrument for Assessment and Classification (AMBIANCE), has been linked to disorganized infant attachment, which, in turn, has been linked to psychopathology. The present study examined the usefulness of the AMBIANCE as an indicator of the efficacy of two brief interventions in reducing atypical behaviors and disrupted communication during play interactions. Twenty‐eight mother–infant dyads participated (14 per intervention). All infants had feeding problems. One intervention, Interaction Guidance, focused on training caregivers to respond sensitively to their infants (play‐focused intervention). The other intervention focused on training mothers to use new feeding techniques (feeding‐focused intervention). Results showed a significant decrease in AMBIANCE scores in the play‐focused group from pre‐ to postintervention, but not in the feeding‐focused group. There was a significant decrease in the level of disrupted communication from pre‐ to postintervention sessions in the play‐focused group but not in the feeding‐focused group. 73% of mothers from the play‐focused group and 17% of mothers from the feeding‐focused group initially classified as “disrupted” attained a classification of “nondisrupted” at the postintervention session. Some limitations of the study include small sample size, differences in timing of assessment for each intervention, and use of samples of convenience. Nonetheless, these findings provide preliminary evidence both of the usefulness of AMBIANCE as an instrument for assessing clinical efficacy and the efficacy of Interaction Guidance. ©2001 Michigan Association for Infant Mental Health.     

Influences of head and torso movement before and during affordance perception

Previous research has shown that body sway (both standing and seated) is related to the accuracy of affordance judgments. The authors investigated the influence of seated head and torso movement on the perception of a novel affordance for wheelchair locomotion. Healthy adults without prior wheelchair experience judged the lowest lintel under which they could roll in the wheelchair. Prior to judgments, participants were given brief (≈ 2 min) practice at self-controlled wheelchair locomotion. During practice, the participant's head either was or was not restrained within the wheelchair. During the subsequent judgment session, the participant's head was or was not restrained. The accuracy of affordance judgments was influenced by restraint during the practice session and also by restraint during the judgment session. The authors collected data on head movement during the judgment session (when participants were not restrained). These data revealed that movement during judgment sessions was influenced by whether or not participants were restrained during the practice session. Overall, the results reveal that the availability of head movements (i.e., being unrestrained) and the nature of head movements (during unrestrained judgment sessions) were causally related to the accuracy of affordance judgments.     

Judging the 'passability' of dynamic gaps in a virtual rugby environment

Affordances have recently been proposed as a guiding principle in perception–action research in sport (Fajen, Riley, & Turvey, 2009). In the present study, perception of the ’passability’ affordance of a gap between two approaching defenders in rugby is explored. A simplified rugby gap closure scenario was created using immersive, interactive virtual reality technology where 14 novice participants (attacker) judged the passability of the gap between two virtual defenders via a perceptual judgment (button press) task. The scenario was modeled according to tau theory (Lee, 1976) and a psychophysical function was fitted to the response data. Results revealed that a tau-based informational quantity could account for 82% of the variance in the data. Findings suggest that the passability affordance in this case, is defined by this variable and participants were able to use it in order to inform prospective judgments as to passability. These findings contribute to our understanding of affordances and how they may be defined in this particular sporting scenario; however, some limitations regarding methodology, such as decoupling perception and action are also acknowledged.     

Perception-action coupling and expertise in interceptive actions

The goal of this experiment was to show that expertise in interceptive actions can be explained by a shorter delay in movement regulation. In this contribution, we tested tennis experts and non-experts using a simulated interceptive task. The experimental device simulated linear motion of an object toward a target on a horizontal runway. Participants had to intercept the simulated moving object with their right hand holding a cart that could slide along a horizontal track perpendicular to the runway. Three different velocity conditions were used: a constant velocity condition that maintained the initial velocity (2m/s) constant until arriving on the target; the decelerated and accelerated velocity conditions, in which the velocity suddenly changed (400 ms before its arrival on the target) from 2 to 1m/s or 3m/s, respectively. Timing accuracy and movement correction after the unexpected velocity change were analysed. The experts were more accurate in the decelerative case (-29 and -124 ms respectively), in the accelerative case (69 and 116 ms respectively), but not in the constant velocity case (2 and 13 ms respectively). Findings can be explained by the shorter visuo-motor delay (VMD: the time required to adapt the movement to the new velocity) for the experts (162 ms) than for the non-experts (221 ms). This shorter VMD offers more time to adapt the interceptive movement to the new velocity. These results can be interpreted as an optimization of the perception-action coupling with expertise.