Perceptual Timing in the Elderley

What differences in timing are found in elderly people? How are these accounted for

by modern timing theory.

Perception of time is a concept that has interested gerontologists for many years.

- Subjective changes- 'Christmas effect'- Christmas comes round quicker each year.

Slowing down of information changes

An increase in age is accompanied by a reduction in verbal & visuospatial processing rate. Peak age=20- 97% processing rate for verbal & visuospatial rate. At 50, 40% visuospatial & verbal 90%. At 70-visuospatial 30% rate, 75% verbal.

Slowing down of internal clock

Waerden, Wearden & Rabbit (1997)- used temporal generalization to investigate possible age-related changes in timing behaviour in participants aged 60-80 years.(divided into 2 groups- 60-69, 70-79).Ps also divided according to IQ (lowest, middle, higher third). The temporal gradients generalization were affected by age- older groups produced flatter gradients compared to younger (i.e. made more errors in identifying comparison durations as the standard). The three IQ groups showed much more marked differences, with the TG gradients for the lowest IQ third being much flatter than for the highest IQ third. Thus, W et al (1997)- results showed a slight decrease in timing precision with increasing age and a mark decrease in precision with decreasing IQ. These findings were attributed to differences in temporal memory variability. Suggesting that prospective timing in the elderly was associated with greater variability of reference memory.

SED theory would explain these finding in terms of 'internal clock pacemaker accumulator'- in order to generate behaviour, clock, memory and decision processes are all involved, so if intergroup differences are found (between elderly participants and younger) this is due to differences at any level at the SED.

Carrasco, Bernal and Redolat (2001)- evaluated age-related differences in the reproduction of a short interval (10 s) using a computerized method. The sample comprised thirteen young adults (M = 26.15 years) and twelve elderly adults (M= 79.1 years). Three parameters of time estimation were measured: estimated time, absolute error, and standard deviation. Results showed that time estimates performed by elderly participants were shorter than those of younger ones, although there were no significant differences between the two age groups in the percentage of absolute errors or standard deviations. These findings could be explained by changes in the rate of the internal clock or to an interaction between more general changes in cognitive processes. However, Carrasco et al (2001) conclude that studies about effects of aging on the estimation of short temporal intervals are not conclusive.

Rammsayer Lima and Wolfgang (1997) In a duration-discrimination experiment, young adults (mean age = 25.1), middle-aged adults (mean age = 45.5), and older adults (mean age = 64.6) were presented with two very brief auditorily marked intervals per trial, and their task was to decide which of the two was longer in duration to a constant standard interval of 50 ms. It was found that duration-discrimination performance was unaffected by age; all three age groups yielded a difference threshold of approximately 17 ms. It was concluded that the ability to discriminate durations of very brief auditory intervals appears to be based on an underlying timing mechanism that does not slow down with advancing adult age.

Wearden (1997) found similar effects using bisection method (Ps initially presentated with 2 standards one short (e.g. 200 ms) and one long (800ms)- then they receive a range of stimulus durations from 200-800ms and have to classify each stimuli in terms of similarity to the long or short version. Findings- No age or IQ effects on bisection points. Furthermore, performance of elderly or low IQ participants were virtually identical to that of undergraduate students 50 years younger. Wearden & Jones (2004)- the finding of consistent age & IQ effects on temporal generalization but bisection is baffling. As ps have 2 remember 2 standards 4 bisection as opposed to one it would seem logical that age and IQ effects would emerge. Allen (2002)- conclusion- participants' are not using the 'standards' in bisection as the standard in temporal generalization. Wearden- this generalization/bisection comparison may tell us more about how timing tasks are performed rather than it does about timing in the elderly per sec.

However, Craik & Hay (1999)- Found very large age effects in a comparison of elderly (M=72.2) with undergrads (22.2). Older groups emitted productions much longer than younger participants and which were very much longer than the real times. Conversely, estimates were smaller than younger groups- (e.g. 120 s estimated as 40 s).

Vanneste, Pouthas and Wearden (2001) tested the spontaneous ticking method. 2 Participant groups (20-30 year olds), (60-76 year olds). The experiment involved either an 'internal temp' condition- ppl tap at rate comfortable to them and 'continuation tapping'- tap rates are synchronised with beeps then tapping continues without beeps. The latter condition is 'calibrated' thus effects of age are eliminated. The internal tempo condition showed that older subjects tapped more slowly than younger and showed greater