Biomedical Engineering Reference
In-Depth Information
repertoire) was chin movements, which resembled those occurring in a situation of mouth
opening. The microswitch for this response included (1) a small box with a position sensor,
which was attached to the side of a hat that the boy was to wear, and (2) a light band that
passed under the boy's chin and connected the position sensor to the other side of the hat.
Downward chin movements pulled the position sensor, thus activating the microswitch,
which in turn caused the occurrence of preferred environmental stimuli. Data showed
that the boy's chin-response frequency increased more than twofold during the interven-
tion phases compared with the baseline periods.
Recently, a different microswitch was conceived to detect a response that can involve
only movements of the lips or can also encompass chin and jaw movements and thus
resemble the one mentioned above (Lancioni et al. 2010c). The microswitch was assessed
with a 41-year-old woman who had suffered severe brain injury and coma after a car
accident and had a diagnosis of a minimally conscious state with pervasive neuromotor
disabilities. The microswitch included two optic sensors consisting of an infrared light-
emitting diode and a mini infrared light-detection unit. The sensors were fixed to a metal
support, which was attached to the woman's chin. When the woman had her mouth semi-
open and the lips clearly apart (i.e., was in her most common position), the aforementioned
sensors were directed at the upper lip and at the mouth cavity, respectively. The relative
position, fixation point(s) of the sensors changed if the woman's lips moved closer together
as well as if they moved further apart. These changes produced microswitch activations,
which resulted in the occurrence of brief periods of preferred stimulation during the inter-
vention phases. Data showed clear increases in the frequency of lip movements during
those phases.
Lancioni et al. (2005a) reported an intervention with a boy of nine years of age, who
presented with profound multiple disabilities and minimal motor behavior. The most
reliable response for him seemed to be eye blinking. A specific response pattern (i.e.,
two blinks occurring within a 2-s interval) was targeted for the study because it was
distinct from the common blinking behavior and occurred at a relatively low frequency.
The microswitch for the response included (1) an optic sensor mounted on an eyeglasses'
frame that the boy wore during the sessions, and (2) an electronic unit that emitted a sig-
nal when a response (two blinks within a 2-s interval) was detected. Response emission
allowed access to brief periods of preferred stimulation during the intervention peri-
ods. Data showed that, during those periods, the child's response rates increased very
markedly.
Lancioni et al. (2006f) set up a program with two children of 10 and 12 years of age and
targeted upward eyelid movements as the response through which they could produce
environmental changes (i.e., causing brief periods of preferred stimulation). The micro-
switch technology involved optic sensors mounted on eyeglasses comparable to those
reported in the study by Lancioni et al. (2005a). However, the functioning of such tech-
nology was somewhat different so that it could detect the response targeted for the two
participants. This consisted of raising one eyelid or both eyelids, as would occur when
looking at something high up. In this study, the optic sensor was not to detect the eyelid
closures (i.e., blinks) as in the study of Lancioni and colleagues (2005a), but rather the tran-
sition from the eyelid to the eye. Such a transition occurred each time the child performed
a looking-up response. Both participants presented extensive response increases during
the intervention periods (i.e., when the performance of the target response allowed them
brief access to preferred stimuli).
The need of targeting double blinking or upward eyelid movements as specific
responses may be fairly obvious in cases in which the conventional blinking response
