"Human Performance", 2008 JASON

We have thus considered the present state of the art in pharmaceutical intervention in cognition and in brain-computer interfaces, and considered how possible future developments might proceed and be used by adversaries.

The most immediate human performance factor in military effectiveness is degradation of performance under stressful conditions, particularly sleep deprivation. If an opposing force had a significant sleep advantage, this would pose a serious threat. However, the technical likelihood of such a development is small at present.

Neural implants involving connections through specific nerve bundles (e.g., ocular, optical) have shown dramatic results for ameliorating severe disabilities, however the level of improvement in all cases is well below the level of normal function. ...At present the primary threat potential for adversarial use of a BrainComputer interface may arise in a feedback mode, in which a the interface provides a soldier with a simple signal or a pain/pleasure pulse in response to externally provided situational information.

Historical instances of human performance modifying activities (e.g. East German Olympic athletes, amphetamine use during WWII, effects of the use of khat in Somalia on US operations) are well known. In contrast, little is known about the present activities of adversaries in using/developing human performance modifiers.

An example of the correlation of diagnostic tests with functional performance is shown in Figure 2.1. The specific study involved tests of the effects of caffeine on performance for a group of Navy SEALS, following 72 hours of intense training activity with almost total sleep deprivation. A variety of metrics were used, including computer-based tests of reaction speed and mental acuity, psychiatric self-assessment surveys, and marksmanship tests. The test was to determine the optimal caffeine dose to ameliorate the effects of fatigue and stress. The results shown in Figure 2. [For instance the percentage of missed targets increased from ∼ 3% for well-rested troops, to about 35% after 72 hours of high-stress training.] reveal substantial improvements in many categories, although it should be noted that the improvements are defined relative to the performance level after 72 hours, which was seriously degraded in all cases relative to measurements taken before training.1 However, despite the substantial improvements in some of the tests of mental acuity, marksmanship was only slightly improved. This shows that general performance metrics, while useful for assessing overall personnel status, cannot be simply extrapolated to predict performance levels for specific military tasks.

We show here that the consequences of gaining a small performance advantage, even if it is highly statistically significant, are likely quite different as regards [military] force-on-force engagements than as regards Olympic competition. In brief, a small performance advantage in force-on-force should generally result in a small change in the outcome, while in Olympic competition it can result in a large change in the outcome.

As an idealized model, suppose that a country’s Olympians are drawn from the extreme tail of a Gaussian (normal) probability distribution with selectivity S. That is, only one out of S in the eligible population (say, country residents between the ages of 16 and 25) can “make the team”. Plausible values of S might be in the range 10^4 to 10^5 . The number of standard deviations t by which a typical Olympic team member exceeds the population mean in some performance variable (long jump distance, e.g.) is then related to the fraction of the population making the team 1/S by ... For large S and t >> 1, an approximate inverse to this relationship is ... So t ≈ 3.5 for S = 10^4 , while t ≈ 4.1 for S = 10^5 .
Put differently, a performance increase of 4.1/3.5 − 1 = 17% (as measured in standard deviations of a performance variable from the population mean) is the equivalent of a full factor of 10 greater selectivity S, from 104 to 105 . This, roughly, is how a small country like the German Democratic Republic (DDR) was able, by the use of performance enhancing drugs, to produce Olympic teams competitive with countries that were an order of magnitude or more larger in population. On the tail of a distribution, small changes in your performance lead to large changes in how many people you are better than.

In addition, under appropriate conditions on the tactical battlefield, sleep deprivation and exhaustion can be and has been exploited militarily as a specific mechanism to weaken opposing forces. This observation, most likely well recognized by senior commanders, is illustrated by accounts of General George Patton’s almost legendary pattern of driving his army with extreme aggressiveness in World War II, based on his stated conviction that it was the way to reach his goal more rapidly and with fewer casualties. The point is to maximally exploit the state of exhaustion of ones enemy. It seems intuitive that, in combat between two armies at comparable levels of sleep deprivation, the advantage is with the force on offense in its ability to stress the opposition’s state of exhaustion. ...These effects also exhibit dramatic consequences in combat situations. Lieberman and coworkers studied soldiers in U.S. Army elite units during a combat simulation field exercise [19]. Wrist activity monitors showed that the solidiers slept about 3 hours per night over a 53 hour period. Twenty four hours after their initial deployment they displayed significant decrements in their cognitive function, including vigilance, memory, reaction time and reasoning. The observed decrement in ability was several-fold worse than individuals whose blood alcohol levels are above the legal limit. Although the combat exercise resulted in multiple stresses in addition to sleep deprivation (e.g. dehydration), the predominant effect leading to the performance decrement was sleep deprivation.

How uniform is the human response to sleep deprivation? A recent study by van Dongen and coworkers demonstrated that there are substantial differences in the abilities of individuals to withstand sleep deprivation. They studied 21 adults from 21 years old to 38 years old, divided into two groups. Each underwent 36 hours of sleep deprivation. One group slept 6 hours a night before the sleep deprivation, and the second group slept 12 hours a night before the deprivation. Every two hours during the sleep deprivation, the subjects were given a variety of neurobehavioral tests, ranging from vigilance tests, digit substitution tests, and critical tracking tests. The subjects demonstrated a substantial individual-to-individual variation in their response to the tests. For example the number of performance lapses to a vigilance test ranged from 10-120 over the 21 subjects after 24 hours of sleep deprivation. In general the magnitude of the interindividual variability was large relative even to the effect of being in the 6 hour sleep group relative to the 12 hour group.

The casualty rate depends weakly on the amount of time that soldiers are allowed to sleep. Within this model if we assume that the soldiers need to sleep around 8 hours per night to maintain their skill levels, as long as they can sleep 5 hours per night there is not a significant increase in the casualty rate. Suppose a human could be engineered who slept for the same amount of time as a giraffe (1.9 hours per night). This would lead to an approximately twofold decrease in the casualty rate. An adversary would need an approximately40 increase in the troop level to compensate for this advantage.

A 2003 U.S. Army Research Institute Study on non-prescription supplement use among Special Forces during the year 2000 showed that 90% of Special Forces soldiers and 76% of support soldiers used supplements. The most common supplements were energy boosters, vitamins, protein powders, and creatine.

A very interesting example of using special training to exploit brain plasticity to aid in recovery from stroke involves robotic training [30]. In this case a 20-year-old woman, Mary O’Regan, had a stroke related to a head injury suffered in a dirt bike accident. She eventually recovered the use of speech and was able to walk again and returned to a life in which her left side remained mainly numb and her left arm was useless. This year, some 20 years later, she is learning to use her left arm again with the aid of a new robotic device called the Myomo e100, developed by John McBean and Kailas Narendran at MIT. This device, shown in Figure 3.4 below, senses weak electrical activity in the muscles of the patient’s arm and uses these signals to provide, “just enough assistance that they can complete simple exercise, like lifting boxes or flipping on light switches. By practicing such tasks, patients may begin to relearn how to extend and flex the arm, rebuilding and strengthening neurological pathways in the process.” Mary reported that the use of the device was, “. . . extremely encouraging.” and that she was able to practice simple tasks like folding towels, opening drawers and lifting objects from one position to another. A small study using the e100 device at the Spaulding Rehabilitation Hospital in Massachusetts showed an average 23% improvement in upper extremity function after 18 hours of training in a 6-week period.[33] The success so far has led to approval by the Food and Drug Administration and planning of studies to extend applications to spinal cord injures and brain trauma, including patients who are military personnel. wounded in Iraq. Further examples abound in the literature regarding brain plasticity and recovery from stroke and other mental afflictions. e.g., reviews by Heiss and Teasel [25] and Johansson [26].

The state of the art is illustrated by the results shown in Figure 4.5. Here the subject rats had electrodes implanted in the medial forebrain bundle (MFB) and in the areas of their somatosensory cortices associated with the left and right whisker bundles. Stimulation of the MFB causes a pleasure response, whereas stimulation of the whisker sensory areas evokes a sensation as if the whiskers were touched. Researchers found it was possible to direct the rats to turn left or right with whisker stimuli, and the rats were trained to move forward in response to the MFB “pleasure” stimulus. With these controls the rats were successfully