Age effects in mental rotation are due to the use of a different strategy

ABSTRACT

Older participants are slower than younger individuals in rotating objects in their minds. One possible explanation for this age effect in mental rotation (MR) relies on the different strategies used. To explore this possiblity, in the present study, younger and older participants were assessed with two MR tasks with three- (Exp.1) and two-dimensional objects (Exp.2)with different complexity levels. In both experiments, the performance of the two age groups was comparable in simple objects. However, systematic differences were observed between the MR rates of younger and older adults while processing complex objects. Younger participants were faster in processing complex than simple objects, whereas older participants were slower in rotating complex as compared to simple objects. These results revealed that different strategies were selected by the two age groups when rotating complex objects. A simplified representation of the objects was transformed by younger participants, while older participants rotated the objects piece-by-piece.

KEYWORDS:

• Mental rotation
• strategy selection
• aging
• unfamiliar objects

Acknowledgments

We thank Dorothy Lawrenson for proofreading the article.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1. In our previous study, poor imagers were defined as those scoring 100 or less on the VVIQ. Therefore, we used this cut-off score to exclude poor imagers in the present experiment.

2. The design of the non-Standard stimuli was different from that of our previous study (Zhao & Della Sala, 2018). In our previous study, the non-Standard objects were designed by withdrawing two cubes from the Standard stimulus, so that a similar configuration characterized both Standard and non-Standard stimuli. However, participants might have mentally filled the missing cube spontaneously on non-Standard trials. In this case stimuli could be considered as volumetric primitives. Therefore, we used a different stimuli design to prevent this possibility.

3. Practice affects MR processing; the RTs drop rapidly after sufficient practice (Mumaw et al., 1984). According to Mumaw et al. (1984), this practice effect modulates the strategy selection in MR by applying the more efficient holistic strategy in well-learned stimuli, whereas using piecemeal transformation in trials before the practice. However, it is notable that such practice effect works for trained types of stimuli only but not for the untrained ones. Therefore, different stimuli types were used for practice.

4. It has been suggested that distinct brain mechanisms are responsible for the discrimination between mirror images and between rotated identical images (e.g. Martinaud et al., 2016). Furthermore, electrophysiological evidence has shown that an additional “flip-over” process is required for the rotation of mirror stimuli in addition to the planar rotation engaged during the rotation of identical stimuli (e.g., Hamm, Johnson, & Corballis, 2004). Because the additional out-of-plane (or non-planar) rotation occurring during the mental transformation of mirror images is still poorly understood and is difficult to isolate from the ongoing planar rotation, we analyzed only trials with identical objects, in line with existing literature (e.g., Khooshabeh, Mary, & Thomas, 2013).