PSYCHOMOTOR SPEED & AGING

• slowing factor of 1.6 - 2.0 in speeded tasks

Birren & Botwinick (1955)

• peripheral nerve conduction velocity not associated w/ slowing

• finger, foot and jaw RTS differed by a constant amount

• peripheral factors - slight effects• central factors - large effects

Theories of Central Slowing

A. Generalized Slowing Hypothesis

• ‘electrical burnout’

• same cognitive operations, but slower rate

• Strong Version: slowing same for all cognitive functions

BUT age differences across tasks depending on type of processing • Weak Version: some slowing evident in all mental operations BUT vague, difficult to validate

B. Resource Reduction Hypothesis

• decrease in quantity of some processing resource(s)

• common attributions:attentional capacity, processing rate, WM

• difficult to access b/c no specific resources identified or measured

• circular reasoning: age differences in performance attributed to reduction inputative resources; reductions in resourcecapacity inferred from performance

C. Disconnection / Neural Network Hypothesis

• processing in neural network w/ links, nodes

• cognitive process = propagation of signal Input Output

• RT = time for signal to reach output node = (# links) x (time/link)

• efficiency fewest links btwn input & output

• aging destroys links, must detour increases number of links

Schematic Neural NetworkNetwork transmits signal left to right. One link in the original,intact route is broken, forcing the signal to detour and addingone more link to the path for a total of nine.From Cerella (1990)

D. Information-Loss Model

4 assumptions:

(1) discrete steps, RT=total time for steps

(2) time/step depends on amount of information available

(3) information is lost during processing

(4) age-related loss in rate of information loss

• not breaks at links, per se, but what happens during processing at each link

E. Increased Cautiousness

• old - decreased tolerance of errors

• difference in speed-accuracy set-point

• lack of exercise of mental functions

• with practice, reduce or eliminate deficits

• to some extent, but biological limit

F. Decreased Use

How can we slow down the slowing?Practice• considerable slowing but old seldom as fast as young

Exercise• physically active older adults faster

Experience (Salthouse,1984)

• 19-72 yr. olds, typing speed, Choice RT, tapping, digit-letter substitution • age-related slowing on CRT but not for typing

• older typists ‘look ahead’, anticipate

Salthouse (1984)

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What is attention?

“Everyone knows what attention is. It is the taking possession by the mind, in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought.” -James, 1890

…but it’s more than simply selecting

ATTENTION & AGING

A redefinition ...

• Focussing on the screen

• Dividing attention between several numbers at once• Inhibiting or Filtering irrelevant information (e.g., blue Es)

• Shifting from one number to another

• Maintenance of an overall state of Vigilance and motivation

SELECTIVE ATTENTION

• choosing what information will be processed

• a lot of information coming in through our senses, but only limited amount can be processed further need to select which information to process

Visual Search Tasks

• find target stimulus among distractors

• as # distractors es, target detection RT es

• older adults - greater RT es

• slope = 0 perfect selectivity

• slope > 0 interference

• slopes for older adults > young adults

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Feature Integration Theory (FI; Treisman & Gelade)

(1) Feature Extraction• representing dimensions

(2) Feature Integration

• putting dimensions together operate serially

Visual processing consists of 2 main steps:

Plude & Doussard-Roosevelt (1989)• acc: FIT, where in sequence of visual info processing is age-related interference?

Plude & Doussard-Roosevelt cont’d ...

• feature search: old and young slope = 0• conjuction search: ed slope for older adults

Only feature integration affected by age

Feature Conjunction

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Plude & Hoyer (1986)Is age-related increased interference just due to age-related reduction in parafoveal acuity?

Search

M Q W V Q

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Plude & Hoyer cont’d ...

• interference greater for old in search condition

When target acuity equated, nontarget interference in visual search with oldConfirms age-related selective attention deficit

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Spatial Cueing Tasks

• advance info re: subsequent target location• when cue location = target location RTs and age differences disappear

Madden (1990)

Noise-Absent: + X

Noise-Present: +

RRRRRXRRRRRRRRRRRRR

Madden cont’d ...

• eccentricity effect was greater for noise- present displays, more pronounced in old

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Retinal Eccentricity

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Some conclusions ...

• age-related differences in feature integration are due in turn to age-related decrements in spatial localization

• however, these differences disappear when information is provided re: location (cueing)

• but, this benefit is reduced for older adults, especially when there is distraction and as the target stimulus moves extrafoveally • practice and experience may help alleviate decrements

Why do older adults sometimes show poor selective attention?

• selective attention = excitation + inhibition

• old have difficulty inhibiting the processing of irrelevant information (Hasher & Zacks, 1988)• measures of brain activity suggest reduced attention-related activity in frontal regions in older adults plus, increased brain responses to irrelevant/ distracting information in modality-specific brain regions in older adults

May & Hasher (1998)

• Stroop Task

green

• ‘synchrony effect’ - older better in the morning

yellow yellowred green

• ability to inhibit may be modulated by time of day in older adults

• old - morning-type • young - evening/neutral-type

• Frontal lobe activity changes with time of day?

CAPACITY• how much information can be processed• automatic minimal demands on attention unaware

Divided Attention (DA) Tasks• simultaneous processing of multiple sources of information, i.e, dual-tasks• success depends on attentional capacity• older adults report difficulties w/ dual-tasks

• controlled demands some/all attention requires awareness

• Craik (1977) - age-related decrements in DA are inevitable

BUT• age-related differences on single-task performance were not considered

• Somberg & Salthouse (1982)

• considered each task alone • equated performance on 2 tasks alone

• age-related DA effect eliminated

• some DA tasks affected by age, some not ...

McDowd & Craik (1988)

• Salthouse & Somberg’s tasks automatic processing require minimal attnal capacity?

• manipulated difficulty of tasks • auditory: listen to list of spoken words

easy female difficult living things

• visual: alphanumeric character on 4-sq. grid easy position difficult cons/vowel/ even#/odd#

• perform each task alone • all combinations of auditory and visual tasks

McDowd & Craik (1988)

task complexity, not DA per se, that accounts for age-related deficits

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position character position character

SUSTAINED ATTENTION (SA)• how well one is able to maintain attention in order to perform a task for a long time

• 2 main measures of SA:

(2) vigilance decrement

• processes involved in vigilance tasks• alertness• adaptation & expectancy

(1) vigilance performance

• sustained allocation of attentional capacity• development of automaticity

Alertness

• related to vigilance performance

• old poorer, related to physiological arousal

Expectancy

• target 10%, informed pr.=10% or pr.=50%

• told incorrect prob. info no age-effect • vary uncertainty of target location• no age-effects w/ low level of uncertainty• age-effect on vigilance performance w/ increasing uncertainty

Automatic vs Controlled Processes

Automatic = fast, reliable, demand little attention, insensitive to cognitive demands

Controlled = slow, variable, demand attention insensitive to cognitive demands

Sustaining controlled attentional processing may be more difficult for older adults• old more susceptible to lapses on Stroop task

• old show more intrusion errors • longer lapses in old• greater fluctuation of attention in old

Can old ‘automatize’ controlled processes?

Rogers et al. (1994)

• train/practice on 1 of 2 visual search tasks

(a) consistent mapping (CM) nonoverlapping target & distractor, same target

e.g., N (target) B D F N T (search) N (target) G N O M Q (search)

(b) varied mapping (VM) target differs on each trial, items server inter-

changeably as targets and distractors

e.g., N (target) B D F N T (search) F (target) G N O F Q (search)

Rogers et al. cont’d ...

• Results: VM task w/ Memory Search - both young and old show DA decrements

• Conclusions:

CM task w/ Memory Search - only old still show DA decrements

old unable to automatize CM task

well-trained target in CM automatically captured attention for young, but not old

DRIVING & AGING

• drivers 75yrs+ have crash rates of 16-24 yr olds• age alone is not the issue, avoid stereotypes• driving = independence • self-restriction is obviously not enough• Ontario physicians must report unsafe drivers

How do we determine when driving is safe? • compendium of illnesses, drugs that make

older drivers unsafe • tests of mental competence• evaluate actual driving performance

Owsley et al. (1998)

• visual acuity weakly associated w/ crash risk• what about visual attention and processing?

• Useful Field of View Test:

• area over which visual info processed rapidly • rapid localization in periphery simultaneous w/ target discrimination centrally • vary eccentricity and duration • score = % reduction in UFOV (0-90%)

• older drivers w/ 40%+ reduction 2.2x more likely to incur crash in 3yr. follow-up

DriveABLE

• develop road test that identifies older drivers who are not competent• observed healthy young and old drivers, as well drivers 65ys+ w/ cognitive impairment

• came up w/ 3 classes of driver error

• Errors That Do Not Count

• Discriminating Errors • Criterion Errors

• many drivers too unsafe, even for road test

DriveABLE Competence Screen

(1) Motor Speed and Control(2) UFOV(3) Complex Judgement(4) Attention Switching (5) Executive Function (6) Component Driving Abilities

• develop competency screen that accurately predicts who is likely to fail/pass road test

• computerized (touch screen),empirically-based

• video clips from driver’s perspective, choose best action to take

DriveABLE Competence Screen, cont’d...

• 2 criterion points set, high accuracy at endpoints

LowerCriterion

Intermediate

UpperCriterion

Low probability offailing road test

PASS

High probability offailing road test

FAIL

No accurate predictionROAD TEST NEEDED