A Lifespan View on Modulation of Peripersonal and Extrapersonal Reach Space via Tool Use

This study examined lifespan characteristics associated with tool use in the modulation of peripersonal and extrapersonal space. Three age groups: Children (7-12 years), Young Adults (19-23 years), and Older Adults (65-92 years) were presented with two experiments using an estimation of reach paradigm involving arm and tool conditions and a switch-block of the opposite condition. Experiment 1 tested Arm and Tool (20 cm length) estimation and switch-block conditions (from Arm to Tool and Tool to Arm) and found a significant effect for Age and Condition (ps <.05). Post-hoc analysis for Age indicated that children were significantly less accurate than young and older adults. Analysis for condition revealed significant differences for the Arm Switch-Block condition (Retraction) when compared to Tool and Arm estimations. Experiment 2 was similar to Experiment 1 with the exception of using a 40 cm length tool. Results were analogous to those found in Experiment 1. Considered together, these results hint that: (1) the ability to be as accurate when estimating reach with a tool and arm is present across the lifespan, (2) development and decline of action representation follow distinct paths, and (3) retraction of space seems to be more difficult than extension.

Children’s use of allocentric cues in visually- and memory-guided reach space

Theory suggests that the vision-for-perception and vision-for-action processing streams operate under very different temporal constraints ( Glover, 2004 ; Goodale, Jackobson, & Keillor, 1994 ; Graham, Bradshaw, & Davis, 1998 ; Hu, Eagleson, & Goodale, 1999 ). With the present study, children and young adults were asked to estimate how far a cued target was from a response target in immediate and response-delay conditions. Based on maximum reach of each participant, target locations in peripersonal and extrapersonal space were created. ANOVA results for accuracy indicated differences between Age within Condition and Space. Overall, adults were more accurate than children. Analysis revealed that with delays of superior or equal to 2 s, performance affected all groups, but most notably the 5- and 7-year-olds. In summary, these findings suggest that young children have greater difficulty processing allocentric cues in the context of reach in delay paradigms.

When estimating reachability in space, young children and the elderly are similar

This study examined the age-related ability to mentally represent action in the context of reach estimation via use of motor imagery in children, young adults, and a group of older adults. Participants were instructed to estimate whether randomly presented targets in peripersonal (within actual reach) and extrapersonal (beyond reach) space were within or out of reach of their dominant limb while seated. In regard to total accuracy, results indicated that children and older adults were similar, but scores were significantly lower than those of young adults. Whereas all groups displayed greater error in extrapersonal space, once again children and older adults were similar, but significantly different than young adults. That is, children and older adults displayed greater overestimation responses. Although other factors are discussed, the literature provides a hint that differences are due in part to distinctions in brain structure and functioning.