PET Flasher: A machine language subroutine for timing visual displays and response latencies

Merikle, Philip M.; Cheesman, Jim; Bray, J.

doi:10.3758/bf03202111

Cited by 15 publications

(14 citation statements)

References 3 publications

(2 reference statements)

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“…The subject's reaction times (in 1/60-sec increments) are then multiplied by 16.67 to provide "millisecond" values for display in the tables. In order to obtain true millisecond timing, a machine language timing loop is required (e.g., Merikle, Cheesman, & Bray, 1982). However, such a subroutine will not solve the problem if responses are made with the PET keyboard.…”

Section: Limitationsmentioning

confidence: 99%

“…For demonstration and undergraduate research purposes, the 1/60-sec resolution seems to suffice. If either of these programs were to be adapted for more advanced purposes (graduate student or faculty research), they would require an external timer or a machine language subroutine (such as that presented by Merikle et al, 1982) and an external response mechanism (e.g., Burgess& Furman, 1984).…”

Section: Limitationsmentioning

confidence: 99%

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PET programs for demonstration and student research in cognitive psychology

Simpson

Burgess

1984

Behavior Research Methods, Instruments, & Computers

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The BASIC programs described here grew partly from a need to create a teaching package for cognitive psychology using the Commodore PET microcomputer. The programs were also designed to be used in an undergraduate laboratory course in human leaming and memory, in which students were required to conduct an experiment of their own designwithin a single semester. A number of existing commercial packages are available for other small computers (e.g., Fischler, 1980;Keenan & Keller, 1980). These are excellent for demonstrating a number of research methods in cognitive psychology, but are somewhat limited in their ability to be adapted to run experiments different from those originally demonstrated.The present package is useful for in-class demonstrations of several experiments widely cited in human memory and cognitive psychology textbooks. Each explains the phenomenon in question, collects data from the subject, and displays a summary of the subject's performance. The programs are written so that they can be adapted easily to student research projects that are similar, but not identical, to those demonstrated. The programs may be modified to generate a large number of experiments based on the four phenomena demonstrated in the original programs.Each of the demonstration programs begins with a brief description of the research on which the demonstration is based. Three of the programs display a graph showing a typical outcome of the research. The subject then is given instructions and led through a series of sample trials, which may be repeated as necessary. The student then serves as subject in the experiment. With one exception, he/she makes responses directly at the keyboard, and when data collection is complete, a summary of the subject's performance is displayed.Each of the programs contains REMARK statements indicating the beginning and ending lines of the major sections of the program (description of research, instructions, experiment, and data summary display). In this way, if a user wishes to adapt the program for research using naive subjects, those portions that should be eliminated or changed (such as the description of the research and its results) may be easily identified. In

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Section: Limitationsmentioning

confidence: 99%

Section: Limitationsmentioning

confidence: 99%

PET programs for demonstration and student research in cognitive psychology

Simpson

Burgess

1984

Behavior Research Methods, Instruments, & Computers

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“…If this is not done, there may be up to 16.67 msec of variability in the reaction time that could obscure small but significant effects (see Lincoln & Lane, 1980). Using a PET/CBM computer, Merikle, Cheesman, and Bray (1982) synchronized display and timing onsets with the rollover of the jiffy clock. The Commodore 64 is more flexible than this because timing and display onsets can be synchronized by the VIC-II raster interrupt with the scan of any video line on the CRT.…”

Section: Vic-ll Raster Interruptsmentioning

confidence: 99%

Using hardware interrupts for timing visual displays and reaction-time key interfacing on the Commodore 64

Wright

Dawson

1988

Behavior Research Methods, Instruments, & Computers

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“…The decoupling of the program and display processes was recognized at an early point in the use of microcomputers for tachistoscopic laboratory applications (Dlhopolsky, 1982;Grice, 1981;Lincoln & Lane, 1980;Merikle, Cheesman, & Bray, 1982;Reed, 1979). Past solutions involved either hardware or software techniques in the Apple II and Commodore PET, and Models I and ill of the TRS-80.…”

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confidence: 99%

Synchronizing stimulus displays with millisecond timer software for the IBM PC

Dlhopolsky

1989

Behavior Research Methods, Instruments, & Computers

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A C language technique for synchronizing millisecond timer software to the appearance of the stimulus on the IBM PC's video monitor is described. Tachistoscopic programs that use the technique can correct the mean 8.3-msec bias normally found in reported response latencies and reduce the associated error variance.Researchers considering the use of the IBM PC for tachistoscopic applications should know that the appearance of a stimulus on the video monitor is controlled by two asynchronous processes: the computer program and the video display circuitry. The program executes instructions that result in the storage of character data (or pixel images) in random access memory (RAM) that is dedicated to the video display. The display processing hardware recurrently reads video RAM and controls the intensity of the monitor's electron beam as it "draws" images. The result: the computer program-which also initiates the timing of response latencies-normally does not know the precise moment at which the display process causes the stimulus to appear on the screen.The decoupling of the program and video processes has a number of effects of interest to researchers who require precise control over brief stimulus displays and millisecond interval timing. As the vertical dimension of the stimulus increases, it becomes more likely that the stimulus will be drawn on the screen in parts. For example, the electron beam might be aimed at the middle of the screen when the program transfers the stimulus data to video RAM. The bottom portion of the stimulus would then appear first, followed by an interval during which the electron beam would be scanning the bottom and then the top of the screen (both areas presumably empty of stimulus parts). Finally, the top portion of the stimulus would appear. The interval between the appearance of first-and last-drawn portions would be 16.7 msec (assuming a monitor with a 6O-Hz refresh frequency).The situation for response latencies produces both biased results and increased error variance. If the program starts a millisecond timer following the execution of the commands to display the stimulus, the timer will have been running an average of 8.3 msec before the stimulus Correspondence may be addressed to Joseph G.

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PET Flasher: A machine language subroutine for timing visual displays and response latencies

Cited by 15 publications

References 3 publications

PET programs for demonstration and student research in cognitive psychology

PET programs for demonstration and student research in cognitive psychology

Using hardware interrupts for timing visual displays and reaction-time key interfacing on the Commodore 64

Synchronizing stimulus displays with millisecond timer software for the IBM PC

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