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Overview


The Behavioral Assessment and Research System (BARS) is a computerized testing program that characterizes neurobehavioral function in populations. The program and user interface have been optimized for use with non-mainstream populations, such as those with limited education or literacy (Rohlman et al 2003). This program has been used in a variety of settings with a broad range of populations, including agricultural workers, adolescents, specific cultural groups, and military members.

Background


The fundamental goal, when developing BARS, was to make a program that optimized computerized neurobehavioral testing for mainstream and non-mainstream populations that would require little examiner interference. Simpler user-interface and instruction styles we ought to be improved upon in BARS versus previous computerized batteries like the Neurobehavioral Evaluation System (NES). BARS was programmed in the early 1990s with Supercard and is administered on Apple Powerbooks running OS9. Predecessors include NES and WHO, but the BARS is an attempt to apply computerized testing to wider populations, who may have not had exposure to computers. This instruction simplification and the use of simple hardware standardizes the process even further reducing the potential for confounding due to personal history or at least making the battery widely applicable. Although BARS is still used today, aging hardware and limited availability of computers has dictated a software upgrade. BARSpc was developed to run on modern hardware using Microsoft Windows operating system. In addition, a new response unit (9Button) that utilizes a USB port has been developed to replace the more complex connections, equipment and independent power source necessary in the older version. BARSpc was recently programmed in Eiffel and is administered on computers running Windows XP as BARSpc.

BARS Components


Instructions

In an attempt to make the tests easier to follow and more accessible, the instructions were split into different steps in which the participant learns the task incrementally. The language is straight-forward and simple. Positive and negative feedback (smiling faces and frowning faces) is given after each correct and incorrect response. In addition to stepped instructions, they all have a auditory component in the form of recorded voices rather than digitize text into sound. Spoken instructions effectively reduces the amount of education required to complete the tests without introducing uncertainty through human instruction. These types of instructions result in less variation due to less potentially uneven examiner variability. Without the spoken instructions, the minimum education required is 10 years.

9button

The 9button interface has been instrumental in administering the tests to multiple populations. Larger buttons on a metal plate is placed over the keyboard have been designed specifically for repeated testing. Simplified interactions with the computer let the subject focus on his or her performance and have had a marked effect on the progression of BARS as an effective, reliable computerized neurobehavioral testing system. Redesigned recently to be used with BARSpc, the 9button unit has been simplified into a USB unit that no longer requires an external power source.

Adjustable parameters

Each test has certain parameters, such as test length, difficulty, stimulus presentation, interval length, that can be changed. The transition to an adjustable format has lead to increased flexibility and a wider range of application. A preliminary study can be conducted to determine the appropriate parameters for the study populations. Children can be presented with shorter, easier batteries to decrease the chance of loss of motivation or testing fatigue. Test completion rates and performances can be maximized by changing length, order or difficulty of the test to adapt to the testing group. Adjustable parameters can also allow for a greater number of tests in each battery, while keeping the number of trials in each test statistically powerful.

BARS tests

Many BARS tests have been derived from established neurobehavioral batteries with well-supported records of effectively discriminating between the exposed and control groups. Newer tests developed in animal and cognitive neuroscience research (Match-to-Sample, Reversal Learning, Progressive Ratio, Selective Attention). BARS tests have consistently shown similar test-retest reliability when performance is compared to those in the original paper format. Neurobehavioral deficits have been accurately identified in early-stage Parkinson patients, symptomatic Persian Gulf War veterans, pesticide-exposed
orchard workers, heat-exposed nuclear waste and aluminum workers, and fuel-exposed Air Force personnel.

BARS Tests and Neurological Function Target

Neurobehavioral Test

Function

Digit Span

Memory and attention

Finger Tapping

Response speed and coordination

Match-to-Sample

Visual memory

Continuous Performance

Sustained attention

Symbol-digit

Coding/information processing speed

Divided Attention

Response and coordination while distracted

Progressive Ratio

Motivation

Reversal Learning

Learning, task switching

Challenges to validation


Cultural, Educational and Gender differences

Differences in test-taking strategies and language can influence performance, creating a false appearance of neurological deficit. Sometimes data transformation can provide modest normalization and control of confounding effects. First the battery is translated into the language if necessary, followed by incorporation of matching voiced directions. In most languages, context and tense must be take into account. Essentially the directions should be a functional translation, not a direct translation.

Differences in performance between males and females have been well-established and are seen in BARS performances as well. Women tend to complete more symbols faster in Symbol Digit. Males recall more digits forward and backward in the Digit Span test. These gender effects can be controlled for by matching gender the exposed groups and unexposed groups.

Differences in amount of education and perhaps where the individual was educated also have statistically different outcomes in the motor tests.

Other Resources


Rohlman DS, Gimenes L, Eckerman DA, Kang SK, Farahat FM, Anger WK. Development of the Behavioral Assessment and Research System (BARS) to Detect and Characterize Neurotoxicity in Humans. NeuroToxicology, 2003, 24: 523-531.

BARS publications

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