Even though consistent changes have been observed using correlational designs, studies that compared performance across age ranges by decades have found most prominent changes in adults older than 70 years (Arena, Hutchinson, & Shimozaki,
2012; Bennett, Sekuler, & Sekuler,
2007; Bogfjellmo et al.,
2013). Most studies indeed compared thresholds between just two age groups, i.e., between younger adults, typically aged between 18 and 30 years, and older adults, typically older than 60 years. Findings often show substantial age-related increase in coherence thresholds (Allen, Hutchinson, Ledgeway, & Gayle,
2010; Andersen & Atchley,
1995; Atchley & Andersen,
1998; Gilmore, Wenk, Naylor, & Stuve,
1992; Snowden & Kavanagh,
2006; Wojciechowski, Trick, & Steinman,
1995; but see also Porter et al.,
2017). Moreover, speed discrimination (Genova & Bocheva,
2013; Norman, Ross, Hawkes, & Long,
2003) as well as motion direction discrimination (Ball & Sekuler,
1986; Bennett et al.,
2007; Bocheva, Angelova, & Stefanova,
2013; Bogfjellmo et al.,
2013) have been found to decline with increasing age. However, results seem to vary largely depending on stimulus parameters such motion direction (Ball & Sekuler,
1986; Pilz, Miller, & Agnew,
2017), stimulus size (Hutchinson, Ledgeway, & Allen,
2014), contrast (Allen et al.,
2010), stimulus duration (Bennett et al.,
2007; Conlon, Power, Hine, & Rahaley,
2017), or location (Wojciechowski et al.,
1995). Indeed, the mechanisms that modulate age effects are often not well understood, but call for caution when trying to derive overall conclusions on functional changes. In the following, the most prominent parameters that modulate age effects on motion perception are considered.