Figure 2. Relationship between spatial memory performance and age. Spatial memory performance as reflected by the number of errors was determined with Barnes maze test and was measured in young (grey symbols, range: 2.4 to 3.5 years old) and middle-aged (black symbols, range: 4.1 to 6.1 years old) mouse lemurs. Spearman correlation of error number and age. The horizontal dotted line illustrates the threshold differentiating good and poor performers.