Effectiveness of adults' spontaneous exploration while perceiving affordances for squeezing through doorways

Performance variability and affordance perception: practice effects on perceptual judgments for walking versus throwing

To judge whether an action is possible, people must perceive "affordances"-the fit between features of the environment and aspects of their own bodies and motor skills that make the action possible or not. But for some actions, performance is inherently variable. That is, people cannot consistently perform the same action under the same environmental conditions with the same level of success. Decades of research show that practice performing an action improves perception of affordances. However, prior work did not address whether practice with more versus less variable actions is equally effective at improving perceptual judgments. Thirty adults judged affordances for walking versus throwing a beanbag through narrow doorways before and after 75 practice trials walking and throwing beanbags through doorways of different widths. We fit a "success" function through each participant's practice data in each task and calculated performance variability as the slope of the function. Performance for throwing was uniformly more variable than for walking. Accordingly, absolute judgment error was larger for throwing than walking at both pretest and posttest. However, absolute error reduced proportionally in both tasks with practice, suggesting that practice improves perceptual judgments equally well for more and less variable actions. Moreover, individual differences in variability in performance were unrelated to absolute, constant, and variable error in perceptual judgments. Overall, results indicate that practice is beneficial for calibrating perceptual judgments, even when practice provides mixed feedback about success under the same environmental conditions.

Towards a common code for difficulty: Navigating a narrow gap is like memorizing an extra digit

What makes a task hard or easy? The question seems easy, but answering it has been hard. The only consensus has been that, all else being equal, easy tasks can be performed by more individuals than hard tasks, and easy tasks are usually preferred over hard tasks. Feghhi and Rosenbaum (Journal of Experimental Psychology: Human Perception and Performance, 45, 983–994, 2019) asked whether task difficulty might reflect a single amodal quantity. Based on their subjects’ two-alternative forced-choice data from tasks involving choices of tasks with graded physical and mental challenges, the authors showed that the difficulty of passing through a narrow gap rather than a wide gap was psychologically equivalent to memorizing an extra .55 digits. In the present study, we extended this approach by adding new arguments for the hypothesis that task difficulty might reflect a single amodal quantity (inspired by considerations of physics, economics, and the common code hypothesis for the study of perception and action), and we tested narrower gaps than before to see whether we would find a larger equivalent memory-digit. Consistent with our prediction, we obtained a value of .95. We suggest that our multi-modal two-alternative forced-choice procedure can pave the way toward a better understanding of task difficulty.

Calibration of perception fails to transfer between functionally similar affordances

Prior work shows that the calibration of perception and action transfers between actions depending on their functional similarity: Practising (and thus calibrating perception of) one affordance will also calibrate perception for an affordance with a similar function but not for an affordance with a disparate function. We tested this hypothesis by measuring whether calibration transferred between two affordances for passing through openings: squeezing sideways through doorways without becoming stuck and fitting sideways through doorways while avoiding collision. Participants wore a backpack to alter affordances for passage and create a need for perceptual recalibration. Calibration failed to transfer between the two actions (e.g., practising squeezing through doorways calibrated perception of squeezing but not fitting). Differences between squeezing and fitting affordances that might have required different information for perception and recalibration are explored to understand why calibration did not transfer. In light of these results, we propose a revised hypothesis-calibration transfers between affordances on the basis of both functional and informational similarity.

Development of affordance perception and recalibration in children and adults

Changes in the body over developmental time (e.g., physical growth) as well as over shorter timescales (e.g., wearing a backpack, carrying a large object) alter possibilities for motor action. How well can children recalibrate their perception of action possibilities to account for sudden changes to body size? The current study compared younger children (4-7 years), older children (8-11 years), and adults as they decided whether they could squeeze through doorways of varying widths. To test for age-related changes in recalibration to modified abilities versus perception of unmodified abilities, half of the participants wore a backpack while making judgments and squeezing through doorways and half did not. Results indicated that judgment accuracy improved with age but that participants had more difficulty when recalibrating to modified abilities. Bias in decision making also changed with age; whereas younger children made riskier decisions by attempting to fit through impossibly small doorways, older children were more cautious. Some particularly cautious participants never generated practice feedback by attempting (and failing) to fit through smaller doorways, which prevented them from recalibrating. Taken together with previous literature, the results of the current study suggest that the development of perception for unmodified versus modified ability proceeds at different rates and depends on the particular motor task.