EXHIBIT 4

                            SENSORMEDICS CORPORATION

                             1984 Stock Option Plan
                        (as Restated through May 1, 1995)

             Section 1.     Description of Plan.     This is the 1984
        Stock Option Plan (as restated through May 1, 1995) (the "Plan"),
        of SensorMedics Corporation, a California corporation (the
        "Company").  Under this Plan, key employees of the Company or of
        any present and future subsidiaries of the Company to be selected
        as below set forth, may be granted options ("Options") to
        purchase shares of the common stock, without par value, of the
        Company ("Common Stock").  For purposes of this Plan, the term
        "subsidiary" means any corporation 50% or more of the voting
        stock of which is owned by the Company or by a subsidiary (as so
        defined) of the Company.  It is intended that the Options under
        this Plan will either qualify for treatment as incentive stock
        options under Section 422A of the Internal Revenue Code of 1986,
        as amended (the "Code"), and be designated Incentive Stock
        Options,or not qualify for such treatment and be designated
        Nonqualified Stock Options.

             Section 2.     Purpose of Plan.   The purpose of this Plan
        and of granting Options to specified employees is to further the
        growth, development and financial success of the Company and its
        subsidiaries by providing additional incentives to certain key
        employees holding responsible positions by assisting them to
        acquire shares of Common Stock and to benefit directly from the
        Company's growth, development and financial success.

             Section 3.     Eligibility.   The persons who shall be
        eligible to receive grants of Options under this Plan shall be
        the officers and key employees of the Company or any of its
        subsidiaries, and those directors of the Company who are also key
        employees.  A person who holds an Option is herein referred to as
        an "Optionee."  More than one Option may be granted to any one
        Optionee.  Notwithstanding the foregoing, the Board of Directors
        of the Company (the "Board") may at any time or from time to time
        designate one or more Directors as ineligible for selection as
        participants in this Plan.

             The aggregate fair market value (determined as of the time
        an Option is granted) of the Common Stock for which any Optionee
        may exercise such Optionee's Incentive Stock Options in any
        calendar year under this Plan and any other incentive stock
        option plans (which qualify under Section 244A of the Code) of
        the Company or any subsidiary shall not exceed $100,000.

             Section 4.     Administration.   The Plan shall be
        administered by a committee (the "Option Committee") to be
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        composed of not less than three members of the Board who are not
        officers or employees of the Company or its subsidiaries,
        selected by and serving at the pleasure of the Board.  The Option
        Committee shall meet at such times and places as it determines
        and may meet through a telephone conference call.  A majority of
        its members shall constitute a quorum, and the decision of a
        majority of those present at any meeting at which a quorum is
        present shall constitute the decision of the Option Committee.

             A memorandum signed by all of its members shall constitute
        the decision of the Option Committee without necessity, in such
        event, for holding an actual meeting.

             The Option Committee is authorized and empowered to
        administer the Plan and, subject to the Plan (i) to select the
        Optionees, to specify the number of shares of Common Stock with
        respect to which Options are granted to each Optionee, to specify
        the Option Price and the terms of the Options, and in general to
        grant Options; (ii) to determine the dates upon which Options
        shall be granted and the terms and conditions thereof in a manner
        consistent with this Plan, which terms and conditions need not be
        identical as to the various Options granted; (iii) to interpret
        the Plan; (iv) to prescribe, amend and rescind rules relating to
        the Plan; (v) to accelerate the time during which an Option may
        be exercised, notwithstanding the provisions of the Option
        Agreement (as defined in Section 12) stating the time during
        which it may be exercised; (vi) to accelerate the date by which
        any unexercised but vested portion of an Option terminates,
        thereby requiring the Optionee to exercise the vested unexercised
        portion of such Option or forfeit it, but in no event shall such
        date be less than two weeks later than the date the Optionee is
        informed of such acceleration; (vii) to permit the continued
        vesting of Options in accordance with the terms of the applicable
        Option Agreement or on an accelerated basis upon the Optionee's
        termination of employment; (viii) to determine, subject to
        Sections 3 and 6 hereof, whether Options will be Incentive Stock
        Options or Nonqualified Stock Options; and (ix) to determine the
        rights and obligations of participants under the Plan.  The
        interpretation and construction by the Option Committee of any
        provision of the Plan or of any Option granted under it shall be
        final.  No member of the Option Committee shall be liable for any
        action or determination made in good faith with respect to the
        Plan or any Option granted under it.

             Section 5.     Shares Subject to the Plan.   The aggregate
        number of shares of Common Stock which may be purchased pursuant
        to the exercise of Options granted under the Plan shall not
        exceed _________ shares, subject to adjustment as provided in
        Section 10 hereof to reflect all stock splits, stock dividends or
        similar capital changes.  Upon the expiration or termination for
        any reason of an outstanding Option which shall not have been
        exercised in full, any shares of Common Stock then remaining
        unissued which shall have been reserved for issuance upon such


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        exercise shall again become available for the granting of
        additional Options under the Plan.  No shares deliverable to the
        Company in full or partial payment of an Option exercise price
        payable pursuant to Section 7 hereof shall become available for
        the grant of other Options under the Plan.

             Section 6.     Option Price.   Except as provided in Section
        11, the purchase price per share (the "Option Price") of the
        shares of Common Stock underlying each Option shall be not less
        than the fair market value of such shares on the date of granting
        of the Option; provided, however, that if an Option is granted to
        an Optionee who is a 10% shareholder of the Company as described
        in Code Section 422A(b)(6) at the time such Option is granted,
        the Option Price shall be not less than 110% of said fair market
        value.  Such fair market value shall be determined by the Option
        Committee on the basis of the reported closing price on such date
        or, in the absence of a reported closing sales price on such
        date, on the basis of the average of the reported closing bid and
        asked prices on such date.  In the absence of either a reported
        closing sales price or reported bid and asked prices, the Option
        Committee shall determine such market value on the basis of the
        best available evidence.

             Section 7.     Exercise of Options.   Subject to all other
        provisions of this Plan, each Option shall be exercisable for the
        full number of shares of Common Stock subject thereto, or any
        part thereof, in such installments and at such intervals as the
        Option Committee may determine in granting such Option, provided
        that (a) each Option shall become fully exercisable no later than
        five years from the date the Option is granted, (b) the number of
        shares of Common stock subject to each Option shall become
        exercisable at the rate of at least 20% per year each year until
        the Option is fully exercisable, and (c) no Option may be
        exercisable subsequent to its termination date.  Options granted
        to an Optionee shall be exercisable without regard to whether
        such Optionee holds any other Options under the Plan.  Each
        Option shall terminate and expire, and shall no longer be subject
        to exercise, as the Option Committee may determine in granting
        such Option, but in no event shall an Option be granted for a
        period in excess of those specified in the first sentence of
        Section 14 hereof.  The Option shall be exercised by the Optionee
        by giving written notice to the Company specifying the number of
        shares to be purchased and accompanied by payment of the full
        purchase price therefor in cash, by check or in such other form
        of lawful consideration as the Board may approve from time to
        time, including, without limitation and in the sole discretion of
        the Board, the assignment and transfer by the Optionee to the
        Company of outstanding shares of the Company's Common Stock
        theretofore held by the Optionee in a manner intended to comply
        with the provisions of Rule 16b-3 under the Securities and
        Exchange Act of 1934, as amended.




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             Section 8.   Issuance of Common Stock.   The Company's
        obligation to issue shares of its Common Stock upon exercise of
        an Option granted under the Plan is expressly conditioned upon
        the completion by the Company of any registration or other
        qualification of such shares under any state and/or federal law
        or rulings or regulations or the making of such investment or
        other representations and undertakings by the Optionee (or his or
        her legal representative, heir or legatee, as the case may be) in
        order to comply with the requirements of any exemption from any
        such registration or other qualification of such shares which the
        Company in its sole discretion shall deem necessary or advisable.
        Such required representations and undertakings may include
        representations and agreements that such Optionee (or his or her
        legal representative, heir or legatee): (a) is purchasing such
        shares for investment and not with any present intention of
        selling or otherwise disposing thereof; and (b) agrees to have a
        legend placed upon the face and reverse of any certificates
        evidencing such shares (or, if applicable, an appropriate data
        entry made in the ownership records of the Company) setting forth
        (i) any representations and undertakings which such Optionee has
        given to the Company or a reference thereto, and (ii) that, prior
        to effecting any sale or other disposition of any such shares,
        the Optionee must furnish to the Company an opinion of counsel,
        satisfactory to the Company and its counsel, to the effect that
        such sale or disposition will not violate the applicable
        requirements of state and federal laws and regulatory agencies.
        The Company will make a reasonable good faith effort to comply
        with such state and/or federal laws,rulings or regulations as may
        be applicable at the time the Optionee (or his or her legal
        representative, heir or legatee, as the case may be) wishes to
        exercise an Option, provided that the Optionee (or his or her
        legal representative, heir or legatee) also makes a reasonable
        good faith effort to comply with said laws,rulings and
        regulations; however, there can be no assurance that either the
        Company or the Optionee (or is or her legal representative, heir
        or legatee), each in the respective exercise of their reasonable
        good faith business judgment, will in fact comply with said laws,
        rulings and regulations.

             Section 9.     Nontransferability.   No Option shall be
        assignable or transferable, except that an Option may be
        transferable by will or by the laws of descent and distribution
        provided such Option explicitly so provides or pursuant to a
        qualified domestic relations order as defined by the Code or
        Title I of the Employee Retirement Income Security Act, or the
        rules thereunder.  During the lifetime of an Optionee, any Option
        granted to him or her shall be exercisable only by him or her or
        such Optionee's former spouse, if transferred in accordance with
        the foregoing sentence.  After the death of an Optionee, the
        Option granted to him or her (if so transferable) may be
        exercised, prior to its termination, only by his or her legal
        representative, his or her legatee or a person who acquired the



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        right to exercise the Option by reason of the death of the
        Optionee or otherwise in accordance with this Section 9.

             Section 10.     Recapitalization, Reorganization, Merger or
        Consolidation.   If the outstanding shares of Common Stock of the
        Company are increased, decreased or exchanged for different
        securities through reorganization, merger, consolidation,
        recapitalization, reclassification, stock split, stock dividend
        or like capital adjustment,a proportionate adjustment shall be
        made (a) in the aggregate number of shares of Common Stock which
        may be purchased pursuant to the exercise of Options granted
        under the Plan, as provided in Section 5, and (b) in the number,
        price and kind of shares subject to any outstanding Option
        granted under the Plan.

             Upon the dissolution or liquidation of the Company or upon
        any reorganization, merger or consolidation in which the Company
        does not survive, the Plan and each outstanding Option shall
        terminate; provided that the Company will give written notice
        thereof to each Optionee at least 30 days prior to the date of
        such dissolution, liquidation, reorganization, merger or
        consolidation in which the Company does not survive, and in such
        event (a) each Optionee who is not tendered an option by the
        surviving corporation in accordance with all of the terms of
        provision (b) immediately below, or who does not accept any such
        substituted option which is so tendered, shall have the right
        until ten days before the effective date of such dissolution,
        liquidation, reorganization, merger or consolidation in which the
        Company is not the surviving corporation, to exercise, in whole
        or in part, any unexpired Option or Options issued to him or her
        which said Optionee is then capable of exercising pursuant to the
        installments provisions of said Option and of Section 7 of the
        Plan; provided, however, that should the Option Committee so
        elect in its sole and absolute discretion, said Optionee may be
        given the right to surrender such Option or Options to the
        Company for a price (which may be payable, in the sole discretion
        of the Option Committee, in cash or in securities of the Company
        or in a combination of both), equal to the difference between the
        aggregate exercise price of that portion of the Option or Options
        which the Optionee is then capable of exercising pursuant to the
        installment provisions of said Option and of Section 7 of the
        Plan and the aggregate fair market value (as determined in the
        manner provided in Section 6 above) of the shares subject to such
        vested portion of the Option or Options on the date one day
        before the effective date of such dissolution, liquidation,
        reorganization, merger or consolidation; or (b) in its sole and
        absolute discretion, the surviving corporation may, but shall not
        be so obligated, tender to any Optionee an option or options to
        purchase shares of the surviving corporation, and such new option
        or options shall contain such terms and provisions as shall be
        required to substantially preserve the rights and benefits of any
        Option then outstanding under the Plan.



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             To the extent that the foregoing adjustments relate to stock
        or securities of the Company, such adjustment shall be made by
        the Board, whose determination in that respect shall be final,
        binding and conclusive.  Except as hereinbefore expressly
        provided in this Section 10, (a) the Optionee shall have no
        rights by reason or any subdivision or consolidation of shares of
        stock of any class or the payment of any stock dividend or any
        other increase or decrease in the number of shares of stock of
        any class, and (b) the number or price of shares of Common Stock
        subject to any Option shall not be affected by,and no adjustment
        shall be made by reason of, any dissolution, liquidation,
        reorganization, merger or consolidation, or any issuance by the
        Company of shares of stock of any class, or rights to purchase or
        subscribe for stock of any class, or securities convertible into
        shares of stock of any class.

             The grant of an Option under the Plan shall not affect in
        any way the right or power of the Company to make adjustments,
        reclassifications or changes in its capital or business
        structures or to merger, consolidate, dissolve or liquidate or to
        sell or transfer all or any part of its business or assets.

             Section 11.     Substitute Options.   If the Company at any
        time should succeed to the business of another corporation
        through a merger or consolidation, or through the acquisition of
        stock or assets of such corporation, Options may be granted under
        the Plan to those employee of such corporation or its
        subsidiaries who, in connection with such succession, become
        employees of the Company or its subsidiaries, in substitution for
        options to purchase stock of such corporation held by them at the
        time of succession.  The Option Committee shall in its sole and
        absolute discretion determine the extent to which such substitute
        Options shall be granted (if at all), the person or persons to
        receive such substitute Options (who need not all optionees of
        such corporation), the number and type of Options to be received
        by each such person, the Option Price of such Option (which may
        be determined without regard to Section 6) and the terms and
        conditions of such substitute Options; provided, however, that
        the Option Price of each such substituted Option shall be an
        amount such that, in the sole and absolute judgment of the Option
        Committee and, if the Options to be granted are Incentive Stock
        Options, in compliance with Section 425(a) of the Code, the
        economic benefit provided by such Option is not greater than the
        economic benefit represented by the option in the acquired
        corporation as of the date of the Company's acquisition of such
        corporation.  Any Option substituted for another option in
        accordance with this Section 11 will expire upon the expiration
        date of such other option (or ten years from the date such Option
        is granted in the case of an Incentive Stock Option, if
        earlier,or ten years and one week in the case of a Nonqualified
        Stock Option, if earlier), and, notwithstanding the provisions of
        Section 7 hereof, will be exercisable during the period in which
        the option would have been exercisable.  Notwithstanding anything


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        to the contrary herein, no Options shall be granted, nor any
        action taken, permitted or omitted, which would cause the Plan,
        or any Options granted hereunder as to which Rule 16b-3 under the
        Securities Exchange Act of 1934, as amended, may apply, not to
        comply with such Rule.

             Section 12.     Option Agreement.   Each Option granted
        under the Plan shall be evidenced by a written stock option
        agreement executed by the Company and accepted by the Optionee,
        which (a) shall contain each of the provisions and agreements
        herein specifically required to be contained therein, (b) shall
        indicate whether such Option is to be an Incentive Stock Option
        or a Nonqualified Stock Option, and if it is to be an Incentive
        Stock Option such agreement shall contain terms and conditions
        permitting such Option to qualify for treatment as an incentive
        stock option under Section 422A of the Code, (c) in the case of
        Optionees who are reporting persons under Section 16 of the
        Securities Exchange Act of 1934, as amended, and the regulations
        promulgated thereunder, may contain the agreement of the Optionee
        not to dispose of the Option or any Common Stock received upon
        exercise of the Option for at least six months from the date of
        the Option grant, (d) may contain the agreement of the Optionee
        to remain in the employ of, and to render services to, the
        Company or any of its subsidiaries for a period of one year from
        the date of the Option, but such agreement shall not impose upon
        the Company or any of its subsidiaries any obligation to retain
        the Optionee in their employ for any period whatever, (e) may
        contain the agreement of the Optionee to resell any Common Stock
        issued pursuant to the exercise of Options granted under the Plan
        to the Company for the Option Price of such Options, and (f) may
        contain such other terms and conditions as the Option Committee
        deems desirable and which are not inconsistent with the Plan.
        The respective stock option agreements evidencing Option grants
        under the Plan need not be identical.

             Section 13.     Rights as a Shareholder.   An Optionee or a
        transferee of an Option shall have no rights as a shareholder
        with respect to any shares covered by this Option until exercise
        thereof except that each Optionee shall have the right to receive
        a copy of the Company's audited financial statements no later
        than 120 days following the end of each fiscal year of the
        Company.  No adjustment shall be made for dividends (ordinary or
        extraordinary, whether in cash, securities or other property) or
        distributions or other rights for which the record date is prior
        to the exercise date, except as expressly provided in Section 10.

             Section 14.     Termination of Options.   Each Option
        Agreement representing an Option granted under the Plan shall set
        forth a termination date, which, for an Incentive Stock Option,
        shall be not later than ten years from the date such Incentive
        Stock Option is granted and which, for a Nonqualified Stock
        Option, shall be not later than ten years and one week from the
        date such Nonqualified Stock Option is granted; provided,


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        however, that if the Option is an Incentive Stock Option and if
        the Optionee is a 10% shareholder of the Company (as described in
        Section 422A(b)(6) of the Code) at the time such Option is
        granted, then the Option shall terminate no later than five years
        form the date of the grant thereof.  In any event, subject to
        clause (vii) of the second paragraph of Section 4 hereof, all
        Options shall terminate and expire upon the first to occur of the
        following events:

                       (a)     the expiration of three months from the
        date of an Optionee's termination of employment by the Company or
        any of its subsidiaries (other than by reason of death), except
        that if an Optionee is then disabled (within the meaning of
        Section 105(d)(4) of the Code), the expiration of one year from
        the date of such Optionee's termination of employment; or

                       (b)     the expiration of one year from the date
        of the death of an Optionee if his or her death occurs while he
        or she is, or not later than three months after he or she has
        ceased to be, employed by the Company or any of its subsidiaries
        in a capacity in which he or she would be eligible to receive
        grants of Options under the Plan; or

                       (c)     the termination of the Option pursuant to
        Section 10 of the Plan;
        or
                       (d)     the termination date set forth in the
        Option Agreement.

             The termination of employment of an Optionee by death or
        otherwise shall not accelerate or otherwise affect the number of
        shares with respect to which an Option may be exercised and such
        Option may only be exercised with respect to that number of
        shares which could have been purchased under the Option had the
        Option been exercised by the Optionee on the date of such
        termination.

             Section 15.     Withholding of Taxes.   The Company may
        deduct and withhold from the wages, salary, bonus and other
        compensation paid by the Company to the Optionee the requisite
        tax upon the amount of taxable income, if any, recognized by the
        Optionee in connection with the exercise n whole or in part of
        any Option or the sale of Common Stock issued to the Optionee
        upon exercise of the Option, all as may be required from time to
        time under any federal or state tax laws and regulations.  This
        withholding of tax shall be made from the Company's concurrent or
        next payment of wages, salary, bonus or other income to the
        Optionee or by payment to the Company by the Optionee of the
        required withholding tax, as the Option Committee may determine.

             Section 16.     Effectiveness and Termination of Plan.  The
        Plan shall be effective on the date on which it is adopted by the
        Board; provided, however, that (a) no Option shall be exercised


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        pursuant to the Plan until the Plan has been approved by the
        shareholders of the Company, and (b) no Option may be granted
        hereunder on or after May 1, 2005.  The Plan shall terminate when
        all Options granted hereunder either have been fully exercised,
        and all shares of Common Stock which may be purchased pursuant to
        the exercise of such Options have been so purchased,or have
        expired; provided, however, that the Board may in its absolute
        discretion terminate the Plan at any time.  No such termination,
        other than as provided for in Section 10 hereof, shall in any way
        affect any Option then outstanding.

             Section 17.     Amendment of Plan.   The Board may (a) make
        such changes in the terms and conditions of granted Options as it
        deems advisable, provided each Optionee affected by such change
        consents thereto, and (b) make such amendments to the Plan as it
        deems advisable.  Such amendments and changes shall include, but
        not be limited to, acceleration of the time at which an Option
        may be exercised, but may not, without the written consent or
        approval of the holders of a majority of that voting stock of the
        Company which is represented and is entitled to vote at a duly
        held shareholder's meeting (a) increase the maximum number of
        shares subject to Options, except pursuant to Section 10 of the
        Plan, (b) decrease the Option Price requirement contained in
        Section 6 hereof (except as contemplated by Section 10 or 11
        hereof) applicable to Incentive Stock Options, (c) change the
        designation of the class of employees eligible to receive
        Options, (d) modify the limits set forth in Section 3 of the Plan
        regarding the value of Common Stock for which any Optionee may be
        granted Incentive Stock Options, unless the provisions of Section
        422A(b)(8) of the Code are likewise modified or (e) in any manner
        materially increase the benefits accruing to participants under
        the Plan.

             Section 18.     Not an Employment Agreement.   Nothing
        contained in the Plan or in any Option Agreement shall confer on
        any Optionee any right to be continued in the employ of the
        Company or one of its subsidiaries.

             Section 19.     Transfers and Leaves of Absence.   For
        purposes of the Plan, (a) a transfer of an Optionee's employment,
        without an intervening period, from the Company to a subsidiary
        or vice versa, or from one subsidiary to another shall not be
        deemed a termination of employment and (b) an Optionee who is
        granted in writing a leave of absence shall be deemed to have
        remained in the employ of the Company during such leave of
        absence.


             Section 20.     Repurchase of Stock.   At the discretion of
        the Option Committee, the Option granted to an Optionee may
        provide that the Company shall have the right, in its sole and
        absolute discretion, to purchase any and all shares of Common
        Stock purchased pursuant to the exercise of Options granted under


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        the Plan if the Optionee leaves the employ of the Company, either
        voluntarily or involuntarily.  Such right shall terminate upon
        the sale of such shares in a broker's transaction in accordance
        with applicable federal and state securities laws, subsequent to
        the date the Company has registered shares of Common Stock under
        the Securities Act of 1933, as amended.  The price for repurchase
        of such shares of Common Stock shall be the higher of the
        original purchase price or the fair market value of such shares,
        as determined in good faith by the Board of Directors of the
        Company, using standard and appropriate valuation
        methods,including without limitation asset valuation, market
        valuation and/or discounted cash flow analysis.  The Company's
        repurchase right hereunder must be exercised for cash or
        cancellation of purchase money indebtedness for the repurchased
        shares within 90 days of termination of the Optionee's
        employment.