# Automation Technology and Human Performance: Current Research and Trends

By Mark W. Scerbo | Go to book overview

on the speed, closing rate, and headway (distance) between pairs of motor vehicles traveling over this stretch of the highway. Sufficient data were collected for a simulation analysis of 35,689 pairs of vehicles. The simulation, a Monte Carlo analysis, was conducted in order to evaluate the potential effectiveness of different collision-warning systems. Without collision warning, Farber and Paley estimated a crash rate of 173 for every million lead vehicle stops. This gives a prior probability or base rate p of .000173. Note that this figure refers to impending collisions, or traffic events that would lead to a collision if the driver took no evasive action. However, because drivers took appropriate action, the data are filtered by human response, so that the base rate of events when the human takes no action is not known. As a first approximation, and in the absence of other data, we assume that the base rate of all impending collisions can be represented by this value. Given this base rate, a detection system with d′ = 5, would yield posterior odds of a true alarm of only I in 3. Even for an extraordinarily sensitive system, with a hit rate of .9999 and a false alarm rate of .0001 (d′ = 7.4), the posterior odds of a true alarm would be only about 2 in 3. These numbers attest to the powerful influence of the base rate on the true alarm rate.

How high should the posterior probability be? Certainly as high as possible; and it seems clear that P(SR) should be greater than .5 for people to attend to alarms. But how much greater? It is known that low posterior probabilities discourage user action ( Parasuraman & Riley, 1997) and also delay speed of response ( Casey, 1993; Getty, Swets, Pickett, & Gounthier, 1995). Assume that the minimum acceptable value of the posterior probability P(SR) = m lies somewhere between .5 and 1.0. The design question now is, given a system with accuracy s and a measured base rate of the collision event of p = b, what should the appropriate decision threshold (ßm) be to achieve a posterior probability of at least m? Equations [1], [2], and [4] can be used to answer this question. Since z[ ] and y[ ] represent non-linear functions, a simple, tractable analytical solution is not possible. But a graphical analysis easily points to the correct solution.

Fig. 1
shows posterior probability functions for a system with d' = 5. The stippled area represents the space of desired performance: posterior probability greater than the minimum m for an a priori probability that is at least b. The decision threshold ßm that guarantees a posterior probability of pm can then be determined by iteration and forward solution of equations [1],
[2]
, and [4]. For example, to achieve m = .8 when b = .001, ßm must be at least 181.1.

Given a specified base rate, our analysis shows how to set ß = ßm in order to optimize performance by achieving a high desired posterior probability m. Of course, the base rate will vary with collision type and with the definition of a impending collision event as a signal. As was mentioned earlier, many collision-warning systems are designed so that the driver can adjust or pre-set the warning distance to be relatively long or short.

CONCLUSIONS

The rapid growth of automation has led to a proliferation of warning and alarm systems. Unfortunately, many warning systems are prone to false alarms, and it is not clear that existing collision- warning systems can be used effectively by drivers to prevent crashes. The quantitative, analytical approach we have presented, based on SDT and Bayesian statistics, provides step-by-step procedures for setting alarm parameters to avoid these problems.

The first step is to specify a maximum false alarm rate for the system. The minimum decision threshold ßf that an alarm system with given sensitivity d' must be set at can then be computed. However, setting a minimum alarm decision threshold to achieve a maximum permissible false alarm rate is necessary but not sufficient for effective alarm performance. In addition, alarm parameters must be designed so that the posterior probability of a true alarm is relatively high for collision events associated with particular base rates of occurrence. Functions relating the required decision threshold ßm to achieve a posterior probability of at least m can be derived for alarm systems of given sensitivity d'.

The analysis we have presented provides a set of standards against which the performance of collision- warning systems can be tested. Although sensitive alarm systems with high detection rates and low false alarm

-66-

If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Default project is now your active project.
Project items
Notes

#### Cited page

Style
Citations are available only to our active members.
Buy instant access to cite pages or passages in MLA 8, MLA 7, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

(Einhorn 25)

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

#### Cited page

Automation Technology and Human Performance: Current Research and Trends

Settings

#### Settings

Typeface
Text size Reset View mode
Search within

Look up

#### Look up a word

• Dictionary
• Thesaurus
Please submit a word or phrase above.

Why can't I print more than one page at a time?

Help
Full screen
Items saved from this book
• Bookmarks
• Highlights & Notes
• Citations
/ 348

### How to highlight and cite specific passages

1. Click or tap the first word you want to select.
2. Click or tap the last word you want to select, and you’ll see everything in between get selected.
3. You’ll then get a menu of options like creating a highlight or a citation from that passage of text.

## Cited passage

Style
Citations are available only to our active members.
Buy instant access to cite pages or passages in MLA 8, MLA 7, APA and Chicago citation styles.

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

## Thanks for trying Questia!

Please continue trying out our research tools, but please note, full functionality is available only to our active members.

Your work will be lost once you leave this Web page.