Biomedical Engineering Reference
In-Depth Information
open and maximally visible when the eye was closed. The variation of the spot dimen-
sion from minimal to maximal levels was recorded as the response. The participant
increased the frequency of such response during the intervention phases of the study
(i.e., when the response allowed access to preferred stimuli) as opposed to the baseline
periods.
18.3 Combinations of Microswitches
The use of a single microswitch is normally directed at promoting a connection between a
specific response and a set of stimuli. The stimuli are accessible to the person only in relation
to his or her performance of the response during the intervention sessions. The possibility
of establishing two or more responses with two or more microswitches would be highly
relevant within any educational and occupational program. It would allow the participant
to extend and vary his or her behavioral engagement, enrich and diversify his stimulation
input, and eventually choose between the different stimuli available on the basis of prefer-
ences and other practical conditions. Table 18.1 provides a list of 11 studies assessing the
combined use of two or more microswitches (Crawford and Schuster 1993; Sullivan et al.
1995; Lancioni et al. 2002a, 2002b, 2004c, 2004d, 2004f, 2006b, 2009b, 2010a, 2010b).
For example, Sullivan et al. (1995) worked with a girl who was 3.5 years of age at the start of
the study. The two responses selected for the girl consisted of head backward movements and
hand-pushing/stroking movements. These responses were used in combination with com-
mercially available pressure microswitches. The microswitches were simultaneously avail-
able and the girl could activate either one of them depending on the response she performed.
The responses allowed her to access different types of preferred stimuli. The results showed
that she increased the frequency of both responses during the intervention conditions.
Lancioni et al. (2002a) reported a study in which two children of 8 and 12 years of age
were involved. The three responses targeted for each participant concerned vocalization,
hand movements (pushing/stroking), and head movements. Each response allowed access
to a specific set of stimuli. The responses were introduced in sequence. Once the first two
responses/microswitches had been introduced individually, the participants were provided
with the opportunity to use them both and choose between them and the stimuli connected
with them. Eventually, the third response/microswitch also was introduced and then com-
bined with the other two. Once the intervention had covered all responses/microswitches,
the participants could use any of them at any time. This response freedom ensured an
extensive and differentiated engagement and an important opportunity to choose among
three sets of preferred stimuli. Data indicated that both participants succeeded in acquiring
the responses and had an increased and consistent use of all three of them.
Lancioni et al. (2004f) conducted a study with two participants of 16 and 20 years of age
who possessed different vocal emissions. The goal of the study was to use the participants'
emissions as different responses allowing them access to different stimulus sources. Three
vocal emissions (one-syllable sounds) were selected for one of the participants and nine
word-like emissions were selected for the second participant. To make the vocal emissions
(responses) functional, computer systems were developed that worked as combinations of
microswitches and could on the whole discriminate the emissions. The software program
used for the discrimination of the emissions of the first participant was based on locally
recurrent neural networks and time sequences of cepstral parameters. The software program
