U.S. patent number 3,877,466 [Application Number 05/435,556] was granted by the patent office on 1975-04-15 for attention-level analyzer.
Invention is credited to Karel Montor.
United States Patent |
3,877,466 |
Montor |
April 15, 1975 |
Attention-level analyzer
Abstract
An attention-level analyzer comprising an electroencephalograph
instrument the output of which is filtered by an analog filter and
a digital filter to pass only brain waves in the 8-13 Hz band,
which is the band of frequencies of the inattentiveness wave. An
output from the filters actuates a clock which, if advanced in time
sufficiently within the predetermined timing interval of another
clock, actuates a tone generator. The output of the first clock
also advances a third clock or counting means in time which, if
advanced sufficiently within the predetermined time interval of a
fourth clock, actuates another tone generator which may be placed
to alert a monitor.
Inventors: |
Montor; Karel (Severna Park,
MD) |
Family
ID: |
23728870 |
Appl.
No.: |
05/435,556 |
Filed: |
January 22, 1974 |
Current U.S.
Class: |
600/545;
340/573.1 |
Current CPC
Class: |
A61B
5/369 (20210101) |
Current International
Class: |
A61B
5/0476 (20060101); A61b 005/04 () |
Field of
Search: |
;128/2S,2.6A,2.6F,2.6R,2.08,2.1B,2.1R ;340/279,407 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Sciaretta et al., "Medical & Biological Engineering," Vol. 8,
No. 5, Sept. 1970, pp. 517-519..
|
Primary Examiner: Kamm; William E.
Attorney, Agent or Firm: Sciascia; R. S. Schneider; P.
Government Interests
STATEMENT OF GOVERNMENT INTEREST
The invention described herein may be manufactured and used by or
for the Government of the United States of America for governmental
purposes without the payment of any royalities thereon or therefor.
Claims
What is claimed is:
1. Apparatus for determining the level of attention of a human
subject comprising, in combination:
wave-detection means adapted for connection to the subject's head
for obtaining an electrical wave output corresponding to the brain
waves of the subject;
filter means for filtering said electrical wave output, said filter
means passing signals having frequencies lying in the attentiveness
band and cutting off lower and higher frequency signals;
first clocking means to which the output of the filter means is fed
as an input for establishing repeatable time intervals and for
producing an output signal if the cumulative duration of
inattentiveness signals exceeds a predetermined amount of time for
a given timing interval; and
first alarm means for producing an alarm signal upon receipt of an
output signal from said clocking means.
2. Apparatus as in claim 1, further including:
second clocking means to which the output of the first clocking
means is fed as an input for producing an output signal if the
number of its input signals during a given timing interval equals a
predetermined number; and
second alarm means for producing an alarm signal upon receipt of an
output signal from said second clocking means.
3. Apparatus as in claim 1, wherein said wave-detection means
comprises an electroencephalographic apparatus.
4. Apparatus as in claim 2, wherein said filter means comprises an
analog filter in series with a digital filter.
5. Apparatus as in claim 1, wherein said first timing means
comprises a pair of clocks, A and B, clock A being of the
continually recycling type and acting to recycle itself and clock B
after each timing interval and clock B being of the type which is
advanced during each timing interval in accordance with the
cumulative duration of any inattentiveness signals coming from the
filter means.
6. Apparatus as in claim 1, wherein said first alarm means
comprises a tone generator.
7. Apparatus as in claim 1, wherein:
said wave-detection means comprises electroencephalographic
apparatus;
said filter means comprises an analog filter in series with a
digital filter;
said first timing means comprises a pair of clocks, A and B, clock
A being of the continually recycling type and acting to recycle
itself and clock B after each timing interval and clock B being of
the type which is advanced during each timing interval in
accordance with the cumulative duration of any inattentiveness
signals coming from said first filter means; and
said first alarm means comprises a tone generator.
8. Apparatus as in claim 7, further including:
second clocking means to which the output of the first clocking
means is fed as an input for producing an output signal if the
number of its input signals equals a predetermined number during a
given timing interval,
said second timing means comprising a clock and a counter, the
clock being of the continually recycling type which acts to recycle
itself and the counter after each timing interval, and the counter
producing an output signal if its count equals said predetermined
number during said given timing interval; and
second alarm means comprising a tone generator for producing an
alarm signal upon receipt of the output signal from said counter.
Description
BACKGROUND OF THE INVENTION
This invention relates to means for indicating the condition of
inattention in an individual and for alerting him to this
condition.
It is obvious that a machine which can measure the level of
attention of an individual and alert him when his attention level
is too low would be valuable in many applications. For example, it
would be useful for alerting the driver of any vehicle, a sonarman
or radarman on watch, and many others, that they are not paying
enough attention to the task at hand.
Another extremely useful application would be the classroom or
individual learning situations where an individual's attention
often starts to wander and he loses part of the instructional
material. This would be prevented by the Attention-Level Analyzer
(ALA).
SUMMARY OF THE INVENTION
The present invention comprises means to detect the brain waves of
a subject and to pass them through a sharp bandpass filter. If this
filter has an output, it means that the subject is being
inattentive. Inattentiveness outputs are fed to clock means which
provide an output to a tone generator if the duration of the
inattentiveness signals during a given time interval rises above a
predetermined amount. The tone generator alerts the subject.
The output of the clock means is also fed to a second clock means
which, if the number of outputs of the first clock means exceeds a
predetermined number in a second, larger timing interval, actuates
a second tone generator to alert a monitor.
OBJECTS OF THE INVENTION
An object of the invention is to monitor the attention level of a
human subject.
Another object is to alert a subject to the fact that his attention
has fallen below a predetermined level.
Other objects, advantages and novel features of the present
invention will become apparent from the following detailed
description of the invention when considered in conjunction with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a representation of a brain wave of an attentive
subject.
FIG. 2 is a representation of a brain wave of an inattentive
subject.
FIG. 3 is a block diagram of an embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
It has been found that the brain waves of a human subject are
different when he is paying attention to something from those when
he is inattentive. FIGS. 1 and 2 show brain waves (alpha waves)
when a subject is attentive and when he is inattentive,
respectively. The frequencies in the attentive wave (FIG. 1)
contain frequencies ranging from about 1/2 to 50 Hz but the
amplitude of its components in the 8-13 Hz range is quite low. On
the other hand, the inattentive wave (FIG. 2) is characterized by
the fact that its components in the 8-13 Hz band (the
inattentiveness band) are of high voltage amplitude. The
differences between these waves form the basis for the ALA.
In FIG. 3, an electroencephalograph (EEG) amplifier 12 has leads,
shown generally by 10, which are attached to the head of a human
subject, not shown. The brain waves of the subject are picked up
and amplified by the EEG means 12 and fed to an analog filter 14
which passes frequencies in the 8-13 Hz band. However, since this
is not a sharp-cutoff filter, the wave is then passed through
digital filter means 16, which cuts the wave off sharply at 8 and
13 Hz, effectively providing a pulse output in the frequency
spectrum.
The digital frequency means 16 also contains a power supply
connected to a switch, which may be a relay, for example. When an
inattention signal which has relatively high threshold level (e.g.,
10 microvolts); in the 8-13 Hz range comes through, the relay
closes the switch, thereby applying an actuating signal to clock
means 30 which comprises clocks A and B (18 and 20,
respectively).
Clock A is set to continually recycle itself at a predetermined
interval, say 3 seconds. Clock B, which acts as a counter, is
actuated by a pulse from the digital filter means 16.
At this point, it is necessary to state that concentration or
attentiveness differs for different people. For example, one person
may spend 1/2 second out of every 3 in daydreaming even when he is
attentive; another may spend a quarter of a second out of every 3
in inattentiveness. Thus, the subject should first be tested to
determine how many fractions of a second he is inattentive even
when he is nominally attentive.
Clock B may typically be set for a 100 percent overlaod, i.e., if
the subject daydreams 1/4 second out of every 3 seconds, clock B
could be set for 1/2 second. Clock B essentially operates like a
counter; the interval of the actuating (inattentiveness) pulse
determines how much time is counted. If 1/2 second or more is
cumulatively counted in the 3-second cycle of clock A, a relay in
clock B is actuated, sending a pulse to an alarm A (22) which may
be a tone generator. The tone put out by the generator A alerts the
subject to the fact that he is not concentrating.
The pulse from the closing of the relay in clock B is also fed to
counter 26 in a second clock means 32, which means also comprises a
clock C (24). Clock C (24) has a cycle of 15 seconds, for example,
after which it resets itself and the counter 26. A pulse from clock
B will start the counter 26 which may be set for 5 pulses, for
example. If 5 pulses are fed to the counter 26 from clock B within
the 15-second cycle of clock C, a relay in the counter means 26 is
closed, thereby actuating another alarm B (28), which also may have
a tone generator, at the instructor's (or any monitoring person's)
location.
Thus, if tone generator A is not keeping the subject alert, a
predetermined number of pulses from clock B, showing prolonged
inattentiveness of the subject, actuate the tone generator B at
monitoring station, so that a monitor can warn the subject of his
lack of concentration.
The predetermined times of the clocks and counter means can be
varied as necessary to fit the needs of different situations.
The types of analog and digital filters which can be used herein
are shown in an article "A Hybrid Circuit to Indicate the Presence
of Alpha Activity" in D. A. Paskewitz, in Psychophysiology, Vol. 8,
No. 1, January 1971.
Clocks A and C may be 5-in-1 timers, Model No. 58033, manufactured
by Lafayette Instrument Company, Lafayette, Ind.
Clock B may be a 5-in-1 timer, Model No. 58034, manufactured by
Lafayette.
The tone generators may be the Model No. 58025 Tone Generator
manufactured by Lafayette.
The EEG amplifier may be the Grass Model 79C EEG.
Obviously, many modifications and variations of the present
invention are possible in light of the above teachings. It is
therefore to be understood that, within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described.
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