SOME ELECTRONIC CONTROL UNITS FOR OPERANT BEHAVIOR STUDIES:III. A TIMER AND COUNTER WITH PRINT-OUT'

W. N. SCHOENFELD, W. W. CUMMING, A. G. SNAPPERand P. HAAS

COLUMBIA UNIVERSITY

The present apparatus supplements devices in our laboratory described earlier (Schoen-feld et al., 1960a and 1960b), and serves as a general timing and counting unit with variedapplications, among them the measurement of response durations and inter-response times,the counting of response or other events in specified time segments, and the printing out ofthese data sequentially.

In serving as a counter of responses or reinforcements (or other class of events), a periodmay be set over which a count is taken. At the end of each set counting period the totalnumber of events is printed out by a Hewlett-Packard 560A Digital Recorder. The shortestinter-event time which can be resolved is 10 microseconds. The length of the counting periodmay be set as low as about 50 ms., with unlimited maximum.As a timer, the apparatus can measure response durations as short as one ms. provided

the responses are separated by not less than 25 ms. Inter-response time may be measuredeither (a) from response onset to onset of the next response, or, (b) from response offset toonset of the next response, the latter being called here "corrected inter-response time"(CIRT in Fig. 2). Both inter-response times may be measured down to a value of 25 ms. withan accuracy of 1.0 ms.

Figure 1 is the schematic flow chart for the entire system. When timing is desired, the sub-ject's response is fed to the coding circuit together with a tone pair of either 10 kc.- 1 kc. or1 kc.-100 cps. generated by a Hewlett-Packard oscillator Model IOOD. The coding circuitgates the given tone pair so as to produce wave trains of the higher frequency of lengthsequal to the intervals being measured. The choice of frequency depends on the accuracydesired, the 10 kc. tone permitting measurement to the nearest 0.1 Ims., the one kc. tone to

ERRORCOUNTER~ ~ ~ EXERA

|S3JECT C|JNE TIME

; [ ~~~~~~~~~~~~~~~ADDITIONAL|

CODING S DECODING AND INPUTS

CIRCUIT * PRINT COMMAND

*T T T + ~~~~~~~~COUNTERS|FREQUENCY 1 TAPESTANDARD ] DECKS PRINTER

Figure 1. Flow chart for the system, including possible additions of external inputs and an external timer.Switch S permits introduction of tape recording, or direct use ofthe decoder, as desired.

'This apparatus was developed in conjunction with research supported by the National Science Foundation un-der Grant G-8671.

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Index for Figure 2

C, -. mf., 200 v.C2 -.00lmf.,200v.C3 -.OOlmf.,200v.C4 -.001 mf., 200 v.C5 -.05 mf., 200 v.C6 -.001 mf., 200 v.C7 -.001 mf., 200 v.C8 -.3mf.,200v.C9 -.037 mf., 200 v.C,0 -.001 mf., 200 v.C,, -.00lmf.,200v.C,2 -. mf., 200 v.C,3 -.00lmf.,200v.C,4 -300mmf.,200v.C,5 -.00l mf., 200 v.

C,6 -.025mf.,200v.C,7 -.2 mf., 200 v.C,8 -.5mf.,200v.C,, -.25mf.,200v.C20 -.00 mf., 200 v.C2, -.00lmf.,200v.B+ -200 v. DCaDb -Sperry diode No. SD20D2 -Sperry diode No. SD20Ec, -EECO Z-90001, Squaring circuitE2 -EECO Z-8327, Pulse gateE3 -EECO Z-8327, Pulse gateE4 -EECO Z-8489, Pulse amplifierE3 -EECO Z-8771, PhantastronE6 -EECO Z-8489, Pulse amplifierE7 -EECO Z-8342, Flip-flopE8 -EECO Z-8489, Pulse amplifierE9 -EECO Z-8489, Pulse amplifierElo -EECO Z-8771, PhantastronE,, -EECO Z-8489, Pulse amplifierE,2 -EECO Z-8327, Pulse gateE,3 -EECO Z-8348, One-shotE,4 -EECO Z-8327, Pulse gateN, -Ne5l neon bulbR, -47 K ohms, 1/2 wattR2 -47 K ohms, 1/2 wattR3 -47 K ohms, 1/2 wattR4 -3 megohms, 1/2 watt

R5 -1.1 megohms, 1/2 wattR6 -470 K ohms, 1/2 wattR7 -100 K ohms, 1/2 wattR8 -5.6 K ohms, 1/2 wattR9 -33 K ohms, 1/2 wattRio -1.5 megohms, 1/2 wattR, I -39 K ohms, 1/2 wattR,2 -470 K ohms, 1/2 wattR,3 -5.6 K ohms, 1/2 wattR -4 10 megohms, 1/2 wattR,5 -47 K ohms, 1/2 wattR,6 -1 megohm, 1/2 wattR,7 -1 megohm, 1/2 wattRi8 -1 megohm, 1/2 wattR,9 -5 megohms, 1/2 wattR20 -270 K ohms, 1/2 wattR2, -75 K ohms, 1/2 wattR22 -22 K ohms, 1/2 wattR23 -100 K potentiometerRY,-Mercurv-wetted-contact relaydRY2 10 K ohm plate relayRY3-General purpose relayRC, -Relay I contactsRC2 -Relay 2 contactsRC3 -Relay 3 contactsS, -3P DT toggle switchS2 -3P DT toggle swvitchS3 -2P DT toggle switchS4 2P DT toggle switchS, -2P DT toggle switchS6 -2P DT toggle switchS7 - IP ST toggle switchSs -4P DT switchT, -One-half 5963 tubeT2 -One-half 5963 tubeT3 -One-half6AL5 diodeT4 -One-half 5963 tubeT5 -One-half 5963 tubeT6 -One-half6AL5 diodeT7 -One-half6AL5 diodeT8 -One-half 12AT7 tubeo -Output to Sodeco counterp -Output to tape recorder or decoder

aAll tube filaments are used with 6.3 volts. The power supply for the complete systems of Figures 2 and 3 should provide well-filtered and regulated B+ at 200 ma. (ofwhich about 30 ma. is in excess of marginal requirement).bAn acceptable substitute is a 6AL5 vacuum tube, or other diode of similar characteristics.cAll EECO plug-in circuits are manufactured and sold by the Engineered Electronics Co., Santa Ana, California.dSimilar to HG 1042 made by C. P. Clare Co.

333

SCHOENFELD, CUMMING, SNAPPER, and HAAS

the nearest millisecond. The second tone of the pair is used to record any special event (suchas reinforcement), its onset resulting in the print-out of a special symbol. Furthermore, thecoding circuit totals, on the mechanical (Sodeco) "error counter," the number of responseswhich occur within 25ms. of a preceding response (and which, for that reason, are nototherwise measured). The coding circuit output is switched to the tape recorder when the10 kc.-l kc. frequency pair is used, or to the decoder when the other pair is used. As stated,use of the tape recorder reduces the "dead" print-out time by a factor of eight since the wavetrains have a minimum of 25ms. between them guaranteed by the coding circuit. The reduc-tion is afforded by recording at 15 inches per second and playing back the tape at 17/8 inchesper second, thus expanding the time between wave trains to match the print-out cycle(200ms.) of the printer. Where 200ms. is an expected inter-response time minimum, the twolower frequencies may be used without tape recording and fed directly to the decoding andprint command circuit. From the latter, the higher frequency wave train of the tone pairbeing used is fed to the electronic counters. At the end of each wave train, the decodingcircuit commands print-out of the electronic counter totals and resets these counters to zero.For special events, signaled by a low frequency wave train, these counters remain blank anda row of zeros is printed.When counting events in a specified time segment, rather than measuring inter-response

times or response durations, the event pulses may be fed directly to the electronic counters.The interval between prints is determined by an external timer which triggers the printingcircuit.

Figure 2 details the coding circuit of the foregoing flow chart. Subject's response is con-verted at E, to a squared wave the duration of which is equal to response duration. Tubes

T, and T2 produce negative pulses, T, at response onset andT2 at response offset. Thethree subsequent subcircuits are concerned with gating the measures of (a) response dura-tion, (b) inter-response time, and, (c) inter-response time minus response duration ("cor-rected" inter-response time). To ease the reading of each subcircuit, a position ofswitches SI-S7 should be assumed. For example, if it is sought to measure inter-responsetimes, S2 must be thrown in the appropriate direction (arrow pointing upward to IR), andSI thrown down (arrow pointing downward to R), and similarly for the other switches.Switch S8 (parts A,B,C,D working together) determines whether tape operation or directoperation is obtained. The gates E2, E3, E,2, and El4 pass pulses or not, depending on whatvoltage (as generated by E5, E7, E13) is controlling them. Lacking input to Es and E,3, theirrespective gates pass pulses. The positive gating pulses generated by E5 and El3 are 25 ms.and 24 ms., or 200 ms. and 198 ms., long, respectively, the shorter pair of output pulsesbeing used with the tape operation. A pulse from E6 puts E, into position to allow gate E,4to pass pulses, and similarly for E8 positioning E, with regard to gate E,2. Furthermore,the output of E5 (pin 6) is differentiated at the input of E2 (pin 4), the latter being underthe control of E13; only the negative pulse resulting from the differentiation of E5's outputwill pass E2 if El3 is not fired simultaneously, while if El3 is firing no pulse passes E2. Pinnumbers are shown on EECO units (E,, E2, E3, Es, El2, E,4) where unusual connections areemployed, or where possible ambiguity exists as to direction of pulse flow (this is also donein Figure 3 below). E10 delays the negative pulse from E, by approximately 100 micro-seconds. When El4 is open, El2 is closed, and vice versa.

As an example of the operation of the coding circuit in Figure 2, consider the switchingmode for measuring IRT's. For this, the switches are in tte position shown in the figure with

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ELECTRONIC CONTROL UNITS

the difference that S7 is to be taken as closed. Assume, further, that a 10 kc. tone is passingthrough El4 to p. The negative pulse generated by T, at response onset passes through SI,S2, S3, S6, and S5, but is finally blocked at E,2. The same pulse also goes through E3 andthen triggers E5. The 25 ms. positive pulse from Es blocks E3 and also is differentiated byC,0; the positive spike derived from the differentiation is inverted by T5, and then is de-layed 100 microseconds by E,O. The output of E,O switches E7, closing El4 and opening E,2.It is this delay which prevents the pulse from T, from passing E12, as stated above. Twenty-five milliseconds later, the negative-going side of E5's output passes through E2, S1, andT6, to switch E7 back to its original state, returning the 10 kc. tone to output point p.If another response (negative pulse from T,) had occurred during the 25 ms. operation of E5,it would have passed through E,2, driving E,3 and generating a 24 ms. pulse which, in turn,would have closed relay 2 (registering a unit on the Sodeco counter connected at o), andwould have blocked E2 (preventing E7 from being switched by the negative-going trailingedge of Es's output). Another response must occur after E5 has finished its cycle before thecircuit will recommence the timing train. Should another response, in fact, occur during theoperation of E5, normal operation would be resumed at the occurrence of the next responsecoming after the completion of the 25 ms. operation of E5. With the arrangement describedhere, only one response occurring within E5's operation time will register on the counter;the counting of all responses within that time, should more than one be made, may be ac-complished by inserting an electronic counter at the output of E12. The operation of thecoding circuit in the other two modes is to be traced in analogous fashion.

Figure 3 details the operation of the decoding circuit. Wave trains of the selected tonepair are fed (from either the tape recorder or directly from the coding circuit) into thiscircuit through transformer TR,. T, and T2 are buffer amplifiers. The-output of T2 is fil-tered to remove the higher frequency tone; the lower frequency is converted at El to a trainof square waves of uniform amplitude which are then differentiated by C3 and R7, rectifiedby T3, and then filtered by the network composed of R8, R,, R1o, and C4. The time con-stant of the network at the grid of T4 is chosen large enough to allow sufficient time for theprinter to complete any cycle going on at the time the low frequency wave train starts. Thenegative bias on T4, whenever the low frequency tone is present, makes the plate of T4 suf-ficiently positive to change the state of E2. The change-over pulse from pin 6 of E2 resetsthe counters to zero, if necessary; the pulse from pin 7 triggers the phantastron E5. The150 ms. positive pulse from E5 closes the gates on the two Hewlett-Packard electroniccounters and initiates the print cycle. The output of T, is filtered to remove the low fre-quency tone, and the remaining high frequency tone is treated in a manner analogous to thatdescribed above for the low frequency tone, with the exceptions, first, that the number ofcycles in the wave train produced at E3 is counted by the electronic counters, and, second,that phantastron Es is triggered only at the end of the high frequency wave train. The twoHewlett-Packard 520AR electronic decade counters have four decades each. The twocounters are used in series (the last decade of one being joined to the first of the otherthrough E6) to produce effectively eight decades.

For use of the circuit as an event counter, switch S1 in the decoding circuit (Fig. 3) isthrown to connect E5 to relay RY,. In this position, activation of RY, by an external timer(or other means) will initiate the print cycle and reset the electronic counters to zero at theend of the cycle. During the print cycle, events are not counted; at the end of the cycle,events are again counted until the next subsequent print signal. Events to be counted are fed

335

336 SCHOENFELD, CUMMING, SNAPPER, and HAAS

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C, -.25mf.,200v.C2 .lmf.,200v.C3 -lmf.,200v.C4 -17.0mf.,200v.C5 -.Olmf.,200v.C6 -'I mf., 200v.C7 -.001 mf., 200 v.Ca -1.Omf.,200v.C -.001 mf., 200v.CIO .001 mf., 200v.C,, -300mmf.,200v.C12 -.001 mf., 200v.C13 -.00 mf., 200v.C,4 -.05mf.,200v.C,5 -.16mf.,200v.C16 -.02mf.,200v.C17 -. mf., 200v.C,8 -2.0 mf., 200 v.C,9 -.001 mf., 200 v.C20 -.103 mf., 200 v.C21 -.005 mf., 200v.C22 -.005 mf., 200v.C23 -.05 mf., 200 v.C24 -.05 mf., 200 v.C25 -.0015 mf., 200v.C26 -50 mmf., 200 v.B+ -200v. DCaDa -Sperry diode No. SD20D2 -Sperry diode No. SD20D3 -Sperry diode No. SD20D4 -Sperry diode No. SD20E, -EECO Z-90001, Squaring circuitE2 -EECO Z-90001, Squaring circuitE3 -EECO Z-90001, Squaring circuitE4 -EECO Z-90001, Squaring circuitE, -EECO Z-877 1, PhantastronE6 -EECO Z-8348, One-shotRI -100 K ohms, 1/2 wattR2 -100 K ohms, 1/2 wattR3 -200 K ohms, 1/2 wattR4 -47 K ohms, 1/2 wattR, -100 K ohm potentiometerR6 -68 K ohms, 1/2 wattR7 -1.0 megohm, 1/2 wattR8 -1.1 megohm, 1/2 wattR - 1.0 megohm, 1/2 wattRIO -150 K ohms, 1/2 watt

RI, -150 K ohms, 1/2 wattR12 -1.0 megohm, 1/2 watt

R,3 -100 K ohms, 1/2 wattR,4 -390 K ohms, 1/2 wattRI5 -100K ohms, 1/2wattR,6 -100K ohms, 1/2 wattR17 -68 K ohms, 1/2 wattR,8 -50 K ohms, 1/2 wattR,9 -150 K ohms, 1/2 wattR20 -150 K ohms, 1/2 wattR2, 5 K ohms, 1/2 wattR22 -270 K ohms, 1/2 wattR23 -20 K ohm potentiometerR24 -180 K ohms, 1/2 wattR25 -1.0 megohm, 1/2 wattR26 -1.0 megohm, 1/2 wattR27 -980 ohms, 1/2 wattR28 -100 K ohm potentiometerR29 -330 K ohms, 1/2 wattR30 -200 K ohms, 1/2 wattR31 -200 K ohms, 1/2 wattR32 -150 K ohms, 1/2 wattR33 -47 K ohms, 1/2 wattR34 -47 K ohms, 1/2 wattR35 -47 K ohms, 1/2 wattR36 -1.0 megohm, 1/2 wattR37 -8 megohm potentiometerR38 -3.0 megohms, 1/2 wattR39 -39 K ohms. 1/2 wattR40 -47 K ohms, 1/2 wattR41 -47 K ohms, 1/2 wattR42 -470 K ohms, 1/2 wattR43 -220 K ohms, 1/2 wattR4 -24 K ohms, 1/2 wattRY -Mercury-wetted-contact relayaRC, -Relay I contactsS, -SP DT toggle switchT, -One-half 5963 tubeT2 -One-half 5963 tubeT3 -One-half6AL5 diodeT4 -One-half 5963 tubeT, -One-half 5963 tubeT6 -One-half 5963 tubeT7 -One-half6AL5 diodeTa -One-half 5963 tubeT9 -One-half6AL5 diodeT10 -One-half 5963 tubeT1l -One-half6AL5 diodeT,2 -One-half 5963 tubeTR, -Audio transformer, 3 ohm input

and 10 K ohm outputaThe footnotes of Figure 2 index apply equally here to the tube filaments and power supply, diodes, EECO units, and mercury-

wetted-contact relay.

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338 SCHOENFELD, CUMMING, SNAPPER, and HAAS

directly into the electronic counter in the form of pulses which must conform to the manu-facturer's minimum specifications (for the Hewlett-Packard 520AR, pulses must be at least0.2 volts). In the present case, we have found it convenient to use the two electronic countersseparately, one for counting responses while the other simultaneously records rein-forcements.

REFERENCES

Schoenfeld, W. N., et al. Some electronic control units for operant behavior studies: I. A response and reinforce-ment contingency translator. J. exp. anal. Behav., 1960,3, 17-20. (a)

Schoenfeld, W. N., et al. Some electronic control units for operant behavior studies: II. A random ratio generator.J. exp. anal. Behav., 1960, 3, 107- 108. (b)

Received June 3, 1960