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Cell Phone Induced Perceptual Impairments During Simulated

Driving

David Strayer, Frank Drews, Robert Albert, and William Johnston

Department of PsychologyUniversity of Utah

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Do Cell Phones Interfere With Driving?

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Driver Inattention & Cell Phones

Currently 120 million cell phone subscribers in US

60% of cell phone time is spent while driving

Tens of millions of people driving while using the cell phone each day

Anecdotal evidence suggests that cell phones interfere driving

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Research Questions

Does conversing on a cell phone interfere with driving?

How significant is the interference?

What are the causes the interference?- Peripheral interference (dialing, holding the phone)- Attentional interference (cell phone conversation)

Legislative initiatives tacitly endorse the peripheral interference hypothesis

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Epidemiological Studies

Redelmeier & Tibshirani (1997) New England Journal of Medicine- p(cell phone in use | accident) = 0.24 - 4 fold increase in risk -- comparable to DUI- No advantage of hands-free phones

Increased risks associated with inattention, rather than dexterity

Limitations: correlational, self selection, intervening variables

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Simulator Study I

Conditions

- Hand-Held Cell Phone- Hands-Free Cell Phone- Radio Control- Book on Tape Control

Conversations

- Clinton Impeachment- Olympic Bribery Scandal

Driving & ConversationDriving DrivingWarm-

up

36 minutes

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Response to Simulated Traffic Signals

Subjects responded to red and green traffic signals

Measures:- Probability of missing signals- Reaction time to detected signals

Preliminary Analysis- Hand-Held = Hands-Free - Radio Control = Book on Tape Control

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Cell Phone

Control

Single Dual

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Simulator Study I

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0.01

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p(M

issi

ng

Sig

nal

)

Cell Phone Control

SingleDual

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Simulator Study I

500

510

520

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540

550

560

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Rea

ctio

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Cell Phone Control

SingleDual

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Conclusions

Using a cellular phone while driving impairs performance

- Twice as likely to miss critical/unpredictable events

- Slower to react to critical/unpredictable events

Cell phone conversation itself causes the interference

Hands-free phones do not appear to be the solution, because the deficits appear to be due to attentional demands imposed by the conversation

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Does the Cell Phone Conversation Affect What We

“See” While Driving? Measured perceptual memory for objects presented at

fixation- While driving alone- While driving and conversing on a hands-free cell phone

Phase I -- Same as Study I, except words were presented at fixation and subjects were to respond if the word was an animal

Phase II -- Measured the implicit perceptual memory for these words using dot clearing paradigm

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Dot-Clearing Procedure

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Simulator Study II

Conditions:- Single-task words (driving only)- Dual-task words (driving & phone)- Control words

Measures: Time to correctly identify word

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Simulator Study II

3000

3050

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Rea

ctio

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Cell Phone

Single

Dual

New Words

Baseline

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Simulator Study II

3000

3050

3100

3150

3200

3250

3300

Rea

ctio

n T

ime

Cell Phone

Single

Dual

New Words

Divided Attention Costs

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Conclusions for Study 2

Impaired perceptual memory for objects presented while driving and conversing on a hands-free cell phone

The cell phone conversation alters how you perceive the driving environment by diverted from driving to other engaging activities

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Ongoing Simulator Studies

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Ongoing Simulator Studies

Hands-free cell phone conversations -- call initiated before driving

Cell phone conversations interfered with driving- Drivers reacted slower to cars braking in front of them - Drivers were 4 times more likely to get in traffic accidents

Driving interfered with cell phone conversations- Impaired memory of conversation- Poorer decision making

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Future Directions How do other advanced technologies affect driving

performance?

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Conclusions

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Future Directions

How does this compare with conversations with passengers in the car?

How does the nature of the conversation modulate the effect?

How does this compare with driving under the influence of alcohol?

How does expertise affect these divided attention deficits?

Are these deficits exacerbated with age?

How great are the individual differences in distraction?

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