Is binding decline the main source of the ageing effect on prospective memory? A ride in a virtual town

Figures & data

Table 1. Sample characteristics.

	Young Group	Older Group
Age (± SD)	24.80 ± 5.70	65.28 ± 7.49
Years of schooling (± SD)	14.17 ± 2.39	12.86 ± 3.40
Mattis (± SD)		141.24 ± 2.01
Sex ratio (women/men)	12/23	14/15

SD = standard deviation.

Figure 1. Illustration of the virtual environment including a view from the virtual driving seat during the experiment (left) and a map of the city (right) showing the location of the prospective cues.

Figure 2. Recall of each component (prospective vs. retrospective) for each type of intentions (Link-EB vs. NoLink-EB vs. TB) among the young (left) and older (right) groups. * p < .05. ** p < .01. *** p < .001. Age effects highlighted on all PM measures are not depicted.

Table 2. Young and older groups’ performances (mean ± standard deviation) on the complementary cognitive assessment.

Cognitive function	Test	Young	Older	p
Retrospective episodic memory
Free recall	RL/RI-16	53.64 ± 5.07	45.00 ± 6.88	<.001
Processing speed	Stroop color	53.68 ± 6.25	58.09 ± 7.27	.003
Executive functions
Shifting	TMT B-A	123.83 ± 67.51	120.51 ± 81.10	.91
Inhibition	Stroop interference	.61 ± .19	1.12 ± .54	<.001
Updating	Running span	34.80 ± 8.34	28.34 ± 7.77	.002
Planning	Zoo	6.84 ± 2.56	4.68 ± 3.50	.003
Binding	Original task	18.96 ± 0.98	15.09 ± 2.96	<.001
Time estimation	Original task	38.30 ± 46.14	37.51 ± 15	.94

Table 3. Forward stepwise regressions on the different PM scores with complementary neuropsychological scores as predictors for the whole sample.

	Step	Predictors	R^2	F	β	p
Link-EB	1	Binding	0.32	28.70	0.56	<.001
NoLink-EB	1	Planning	0.20	16.68	0.46	<.001
	2	Planning	0.29	9.55	0.36	0.003
		Retros. memory		6.43	0.29	0.014
TB	1	Binding	0.30	26.50	0.55	<.001
Prospective	1	Binding	0.44	48.62	0.66	<.001
component	2	Binding	0.48	33.82	0.57	<.001
		Processing speed		6.26	−0.25	0.015
Retrospective	1	Binding	0.39	39.00	0.62	<.001
component	2	Binding	0.48	23.52	0.49	<.001
		Retros. memory		10.27	0.32	0.009

Figure 3. Mediation of the effect of ageing on prospective memory for (1) Link-EBPM intentions, (2) NoLink-EBPM intentions, (3) TBPM intentions, (4) the prospective component (ProCom), and (5) the retrospective component (RetCom). Coefficients correspond to the beta weights. ns = nonsignificant. * p < .05. ** p < .01. *** p < .001.

Table A1. List of intentions.

Link-EB	NoLink-EB	TB
Buy a TV magazine at the newsstand	Buy glasses at the fountain	Call the restaurant to book a table after 2 minutes
Check the bus timetables at the bus shelter	Make an appointment with the dentist at the car park	Fill up with gas after 3 minutes
Buy a book of stamps at the post office	Buy a calendar at the city hall	Take a pill after 4 minutes

Table A2. Two-sample t-tests for participants’ performance in post-test free and cued recalls of intentions.

Post-test recall /3	Young	Older	p
Free recall
Link-EB	2.66 ± 0.54	2.00 ± 0.76	<.001
NoLink-EB	2.56 ± 0.62	2.00 ± 0.80	.002
TB	2.63 ± 0.59	1.90 ± 1.05	<.001
Cued recall
Link-EB	3.00 ± 0.00	2.83 ± 0.38	.010
NoLink-EB	2.76 ± 0.49	2.38 ± 0.78	.021
TB	2.71 ± 0.57	2.17 ± 0.85	.003