AGE-RELATED EFFECTS ON DRIVING

AGING, DRIVING AND CONVERSATION

• Are age-related differences in driving performance present when driver is engaged in a conversation?

• older adults exhibit greater cost when performing dual-task as well as slower response in variety of tasks

• does greater experience in driving offset the decline in multi-tasking?

• If present, does the cost of driving while conversing effect both tasks equally?

• previous research has found poorer driving performance while conversing, but what about the speech performance?

• do drivers distribute resources evenly between the two task?

• do older drivers exhibit the same strategy as younger while conversing?

• Does the location of conversation partner affect driving performance?

• does viewing the same environment lead to modulation of speech performance of a passenger?

Age-related effects of conversation with a passenger or a caller on driving performance

Ensar Becic, Tate Kubose, Kathryn Bock, Gary Dell, Susan Garnsey and Arthur KramerUniversity of Illinois at Urbana-Champaign

PARTICIPANTS

ABSTRACTThe effects of conversation and age-related differences on driving performance were investigated while drivers conversed with an in-vehicle passenger or an outside-vehicle caller. All participants completed two single-task blocks and one dual-task block. The results showed greater variability in velocity, lane keeping and steering control under single-task than under dual-task conditions. However, when crossing an intersection, a task requiring greater attentional resources, drivers exhibited a cost due to the dual task. Older drivers exhibited greater variability in velocity, stayed closer to the center of the lane, and waited longer to cross intersections than their younger counterparts, suggesting that they compensate for their declining perceptual and cognitive abilities through changes in driving behavior. Drivers exhibited greater variability in steering under single-task conditions when talking to an outside-vehicle caller, and older drivers showed greater variability in velocity when conversing with an outside-vehicle caller. Older adults recalled fewer details from the speech task compared to younger participants. Drivers exhibited poorer recollection of the speech task than their partners and participants in an in-vehicle condition showed a more accurate recollection of the speech task than those in an outside-vehicle condition.

CONCLUSIONS

• 48 pairs of Younger Participants

• 18-24 years of age (mean = 19.6 years)

• 48 pairs of Older Participants

• 57-88 years of age (mean = 71 years)

• All participants demonstrated normal or corrected to normal vision

In-vehicle Outside-vehicle24 pairs 24 pairs driver/passenger driver/caller

• two single blocks (driving and conversing only)• one dual-task block (driving while conversing)

Driving Task

- driving through an urban environment- crossing busy intersections- obeying rules of the road- drive at 30 m/h- stay in the center of the lane- cross intersections safely and in a timely manner

Speech TaskStory Retelling Task (Brown & Dell, 1987)• pair member 1 hears a story

- retells it to pair member 2• pair member 2 hears a story

-retells it to pair member 1

• at the end of speech block, both members are required to recall the stories told to them by their partners

METHODS

Average Lane Position

Location of the non-driver

Inside-vehicleOutside-vehicle

Ave

rage

Lan

e P

ositi

on (

m)

.32

.30

.28

.26

.24

.22

.20

.18

Older Single

Older Dual

Young Single

Young Dual

• older drivers stayed closer to the center of the lane

Additional Findings

• older drivers exhibited greater variability in velocity on straight-aways

• age effects present under single-task condition, but absent under dual-task

• older drivers took longer to cross intersections

EFFECTS OF DUAL TASK ON DRIVING

Variability of Lane Position Keeping

Main Effects• older participants recalled fewer stories

• drivers recalled fewer story details than passenger/caller

• participants in the outside-vehicle condition recalled fewer stories

Additional Findings

• drivers exhibited greater variability in velocity under single-task conditions

• drivers stayed closer to the center of the lane under dual-task conditions

• drivers drove more slowly under dual-task conditions

SPEECH TASK PERFORMANCE

• Additional cost in speech production as a result of more demanding driving situation• Demanding driving imposes greater cost on production than comprehension

Location of the non-driver

In-vehicleOutside-vehicle

Var

iabi

lity

of V

eloc

ity (

m/s

)

1.4

1.2

1.0

.8

.6

.4

Older Single

Older Dual

Young Single

Young Dual

• older drivers exhibited greater variability in velocity than younger when talking to a cell-phone caller

• age difference is reduced when talking to a passenger

Variability of Velocity

LOCATION OF THE CONVERSATION PARTNER AND

AGING

• average and standard deviation on measures of velocity, lane position and steering• time to cross intersection• # of stories recalled• gist scoring, percentage of propositions correctly recalled

Design

2 x 2 x 2 mode ANOVA • task (single, dual)• age (older, younger)• location of the conversation partner

• (in-vehicle, outside-vehicle)

• role (driver, passenger/caller)

MEASURES

• greater variability in lane position keeping when driving only

• Conversing with a passenger/caller produced less variable lane position keeping and velocity• Conversing with a passenger of a cell-phone caller resulted in more consistent driving performance

• A large dual-task cost is exhibited in speech task, rather than in driving performance suggesting prioritization of tasks

• Language use suffers as a result of a routine driving• Additional driving demands impose greater cost on language use

• Attention demanding task imposes additional cost on speech production

ACKNOWLEDGEMENTSSupport: We are grateful to for the support from General Motors

and Beckman Institute for this research.

End

Start

Route

Retelling

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Driver Non-Driver

Pro

po

rtio

n C

orr

ec

t

Straight-away

Intersection

Recall

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Driver Non-Driver

Pro

po

rtio

n C

orr

ect

Straight-away

Intersection

Driving Demands and Speech Performance

Age-related Effects in Language While Driving

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Retelling Recall

Pro

po

rtio

n C

orr

ect

Older Single

Older Dual

Younger Single

Younger Dual

• Older drivers do no exhibited additional dual-task cost