Increasing the versatility of the Scientific Prototype 3-channel tachistoscope
1
Increasing the versatility of the Scientific Prototype 3-chanriel tachistoscope MICHAEL H. ROWE and JACK H. SANDWEISS, CALIFORNIA STATE COLLEGE AT LOS ANGELES, Los Angeles, California 90032 Because of its relatively low cost and high degree of flexibility, the Scientific Prototype Model GB 3-channel tachistoscope is one of the more popular commercially available units. With this instrument, precise tachistoscopic presentation of one, two, or three visual stimuli can be achieved, and a variety of sequences and temporal relationships can be programmed easily without the aid of any external devices. However, in experiments requiring the successive presentation of three stimuli (i.e., masking studies), it is difficult to program internally interstimulus intervals between any pair of stimuli. Nevertheless, through the use of simple RC networks in conjunction with the front panel functions of the instrument, such intervals can be easily and inexpensively provided. In normal operation, all connections between each channel timer and the relevant stimulus lamp are internal. There are, however, front panel provisions whereby appropriate logic signals can .> 100., -,. 901 o sol fz:l I 70 1 110 ..... 40 Eo-< 30 :10 10 ------T a 4 III 8 10 ia 14 1111 I!I :ao ':lOO CAPACITANCE (Mfd.l Fig. I. Time delay as a function of capacitance with a constant lo-ohm resistance. maintain on or off states of the lamp driver : independent of the state of the channel timer. The channel timer itself is operated by applying a -7·Y de logic signal to the timer input jack and provides an identical -7-Y de signal through the gate output jack during its on state. In addition, the inverse output jack provides a -7-Y dc logic signal during the off state of the timer, which can be used to trigger subsequent channels for sequential presen tations. In order to obtain specific interchannel intervals when all three channels are in volved in sequential stimulus presentation, the procedure is simply to have any given lamp driver momentarily inhibited by the gate output of its own channel timer through an appropriate RC circuit. This is accomplished by running a lead from the gate output of any channel timer through the RC circuit into the inhibit jack of its own lamp driver. In this way, the lamp driver is maintained in an off state for a duration determined by the RC time constant even though the channel timer is on. Such an arrangement has been set up in our laboratory using a constant lD-ohm resistance in series with capacitance values ranging from I to 200 MF. All time constants were measured by using a Tektronix Model S02A dual-beam oscilloscope to monitor the logic signal inputs to each channel timer and its own lamp driver. Interchannel intervals were found to be an exact linear function of capacitance with I MF providing 5 msec duration (see Fig. 1). When using this method, it is important to remember that the auxilliary interchannel intervals must be subtracted from the setting of the inhibited channel timer in order to determine the actual stimulus duration for that channel. Thus, interstimulus intervals can be added to the existing programmable functions of the instrument when three stimuli are being presented. Superphosphate in the control of vivarium odor THOMAS B. COLLINSl and MARION D. HARLESS,2 CENTRAL WASHINGTON STATE COLLEGE, Ellensburg, Washington 98926 Odors are generally not a problem in the contemporary rodent vivarium, but they are often annoying in a restricted research situation. During long-term studies where minimal cage cleaning and interference is mandatory, ammonia effects may become objectionable as urine accumulates. While engaged in such research, the authors were able to minimize the irritating and odorous effects of ammonia buildup by using superphosphate. Superphosphate can either be mixed into the collecting tray material (sawdust, bagasse, commercial litters) or sprinkled over the surface of the material. The commercially available liquids, wick devices, sprays, and gelatins are sometimes helpful in odor control. Although the cost Behav.Res. Meth. & Instru., 1970, Yol. 2 (2) of these agents is generally not prohibitively high, they are expensive. A greater deterrent to the use of the commercial agents is the odor they produce in an attempt to mask vivarium smells. Superphosphate, instead of introducing new odors to cover the ammonia odor, bonds with the free ammonia in the animals' urine, thus eliminating the ammonia as an irritant (Collings, 1949). According to county agricultural agents who were interviewed, phosphates and superphosphates have been used for some time as odor reducers by many poultrymen who maintain chickens on litter floors. No actual data were collected, but superphosphate perceptibly diminished the irritating effects of ammonia buildup to the eyes and noses of human observers. It seems probable that the diminution was noticeable to the rodents involved; however, there were no observable changes in cage activity or ongoing behavioral testing folloWing the introduction of the superphosphate. Superphosphate currently costs less than $4.00 for 80 pounds and may be purchased from any distributor of farm products. The amount to be used depends upon the moisture content of the collecting-tray litter, the number of animals per cage, etc., and is best determined through "trial and success." REFERENCE COLUNGS, G. G. Commercial fertilizerl. (4th ed.) Philadelphia: BIaJcirton, 1949. NOTES 1. Now at Mankato State College, Mankato, Minnesota 56001. 2. Now at Midwestern University, Wichita FaDs, Texas 76308. 9S
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Transcript of Increasing the versatility of the Scientific Prototype 3-channel tachistoscope
Increasing the versatility of theScientific Prototype 3-chanriel
tachistoscope
MICHAEL H. ROWE and JACK H.SANDWEISS, CALIFORNIA STATECOLLEGE AT LOS ANGELES, LosAngeles, California 90032
Because of its relatively low cost andhigh degree of flexibility, the ScientificPrototype Model GB 3-channeltachistoscope is one of the more popularcommercially available units. With thisinstrument, precise tachistoscopicpresentation of one, two, or three visualstimuli can be achieved, and a variety ofsequences and temporal relationships canbe programmed easily without the aid ofany external devices. However, inexperiments requiring the successivepresentation of three stimuli (i.e., maskingstudies), it is difficult to program internallyinterstimulus intervals between any pair ofstimuli. Nevertheless, through the use ofsimple RC networks in conjunction withthe front panel functions of theinstrument, such intervals can be easily andinexpensivelyprovided.
In normal operation, all connectionsbetween each channel timer and therelevant stimulus lamp are internal. Thereare, however, front panel provisionswhereby appropriate logic signals can
1~ .>100.,
-,. 901o solfz:l I~ 70
1
~ 110
~80..... 40Eo-<
30
:10
10
~------ ------T ~a 4 III 8 10 ia 14 1111 I!I :ao ':lOO
CAPACITANCE (Mfd.l
Fig. I. Time delay as a function ofcapacitance with a constant lo-ohmresistance.
maintain on or off states of the lamp driver :independent of the state of the channeltimer. The channel timer itself is operatedby applying a -7·Y de logic signal to thetimer input jack and provides an identical-7-Y de signal through the gate outputjack during its on state. In addition, theinverse output jack provides a -7-Y dclogic signal during the off state of thetimer, which can be used to triggersubsequent channels for sequentialpresentations.
In order to obtain specific interchannelintervals when all three channels arein volved in sequential stimulus
presentation, the procedure is simply tohave any given lamp driver momentarilyinhibited by the gate output of its ownchannel timer through an appropriate RCcircuit. This is accomplished by running alead from the gate output of any channeltimer through the RC circuit into theinhibit jack of its own lamp driver. In thisway, the lamp driver is maintained in anoff state for a duration determined by theRC time constant even though the channeltimer is on.
Such an arrangement has been set up inour laboratory using a constant lD-ohmresistance in series with capacitance valuesranging from I to 200 MF. All timeconstants were measured by using aTektronix Model S02A dual-beamoscilloscope to monitor the logic signalinputs to each channel timer and its ownlamp driver. Interchannel intervals werefound to be an exact linear function ofcapacitance with I MF providing 5 msecduration (see Fig. 1).
When using this method, it is importantto remember that the auxilliaryinterchannel intervals must be subtractedfrom the setting of the inhibited channeltimer in order to determine the actualstimulus duration for that channel. Thus,interstimulus intervals can be added to theexisting programmable functions of theinstrument when three stimuli are beingpresented.
Superphosphate in the control of vivarium odor
THOMAS B. COLLINSl and MARION D.HARLESS,2 CENTRAL WASHINGTONSTATE COLLEGE, Ellensburg,Washington 98926
Odors are generally not a problem in thecontemporary rodent vivarium, but theyare often annoying in a restricted researchsituation. During long-term studies whereminimal cage cleaning and interference ismandatory, ammonia effects may becomeobjectionable as urine accumulates. Whileengaged in such research, the authors wereable to minimize the irritating and odorouseffects of ammonia buildup by usingsuperphosphate. Superphosphate can eitherbe mixed into the collecting tray material(sawdust, bagasse, commercial litters) orsprinkled over the surface of the material.
The commercially available liquids, wickdevices, sprays, and gelatins are sometimeshelpful in odor control. Although the cost
Behav.Res. Meth. & Instru., 1970, Yol. 2 (2)
of these agents is generally notprohibitively high, they are expensive. Agreater deterrent to the use of thecommercial agents is the odor theyproduce in an attempt to mask vivariumsmells. Superphosphate, instead ofintroducing new odors to cover theammonia odor, bonds with the freeammonia in the animals' urine, thuseliminating the ammonia as an irritant(Collings, 1949). According to countyagricultural agents who were interviewed,phosphates and superphosphates have beenused for some time as odor reducers bymany poultrymen who maintain chickenson litter floors.
No actual data were collected, butsuperphosphate perceptibly diminished theirritating effects of ammonia buildup tothe eyes and noses of human observers. Itseems probable that the diminution wasnoticeable to the rodents involved;
however, there were no observable changesin cage activity or ongoing behavioraltesting folloWing the introduction of thesuperphosphate.
Superphosphate currently costs less than$4.00 for 80 pounds and may be purchasedfrom any distributor of farm products. Theamount to be used depends upon themoisture content of the collecting-traylitter, the number of animals per cage, etc.,and is best determined through "trial andsuccess."
REFERENCECOLUNGS, G. G. Commercial fertilizerl. (4th
ed.) Philadelphia: BIaJcirton, 1949.
NOTES1. Now at Mankato State College, Mankato,
Minnesota 56001.2. Now at Midwestern University, Wichita
FaDs, Texas 76308.
9S
