Using Arduino microcontroller boards to measure response latencies

Latencies of buttonpresses are a staple of cognitive science paradigms. Often keyboards are employed to collect buttonpresses, but their imprecision and variability decreases test power and increases the risk of false positives. Response boxes and data acquisition cards are precise, but expensive and inflexible, alternatives. We propose using open-source Arduino microcontroller boards as an inexpensive and flexible alternative. These boards connect to standard experimental software using a USB connection and a virtual serial port, or by emulating a keyboard. In our solution, an Arduino measures response latencies after being signaled the start of a trial, and communicates the latency and response back to the PC over a USB connection. We demonstrated the reliability, robustness, and precision of this communication in six studies. Test measures confirmed that the error added to the measurement had an SD of less than 1 ms. Alternatively, emulation of a keyboard results in similarly precise measurement. The Arduino performs as well as a serial response box, and better than a keyboard. In addition, our setup allows for the flexible integration of other sensors, and even actuators, to extend the cognitive science toolbox.     

Metronome LKM: An open source virtual keyboard driver to measure experiment software latencies

Experiment software is often used to measure reaction times gathered with keyboards or other input devices. In previous studies, the accuracy and precision of time stamps has been assessed through several means: (a) generating accurate square wave signals from an external device connected to the parallel port of the computer running the experiment software, (b) triggering the typematic repeat feature of some keyboards to get an evenly separated series of keypress events, or (c) using a solenoid handled by a microcontroller to press the input device (keyboard, mouse button, touch screen) that will be used in the experimental setup. Despite the advantages of these approaches in some contexts, none of them can isolate the measurement error caused by the experiment software itself. Metronome LKM provides a virtual keyboard to assess an experiment’s software. Using this open source driver, researchers can generate keypress events using high-resolution timers and compare the time stamps collected by the experiment software with those gathered by Metronome LKM (with nanosecond resolution). Our software is highly configurable (in terms of keys pressed, intervals, SysRq activation) and runs on 2.6–4.8 Linux kernels.     

The 3RT Test: Three reaction time tasks for IBM PC computers

The 3RT Test consists of a simple, a choice, and a conditional reaction time (RT) task. The three tasks involve comparable visual stimuli and require identical manual responses, but they differ in the complexity of cognitive processing required. The nonverbal stimuli convey commonly known meanings. Responses can be made either on the keyboard or on response keys connected to the computer’s serial port. The computer’s internal timer/counter is used for millisecond timing. The test administration program allows flexible setting of the test conditions. The data analysis program provides summary data not only for each RT task as a whole, but also for separate trial types within each task. Summary statistics include measures of variation and central value that are not affected by extreme scores. In addition to laboratory studies with normal adults, the 3RT Test is suitable for life-span developmental studies, cross-cultural comparisons, and other uses in various clinical settings.     

Response Latency to Computer-Administered Inventory Items as an Indicator of Emotional Arousal

The response latencies of college students to computer-displayed emotionally arousing or emotionally neutral self-report statement were investigated. Arousing and neutral statements were matched for word and character length to control for reading time. Subjects responded to statements by pressing T (for true), F (for false), or the space bar (for cannot say) keys on the keyboard, and the computer recorded the elapsed time from the onset of each statement's display until the subject's response. Results indicated that response latencies were significantly longer for the arousing items. The findings suggest that the recording of response latencies in computerized personality inventories may help identify item content areas that individuals find emotionally arousing. Other possible clinical and research uses for response latencies in computerized inventories are discussed.     

Suitability of the IBM XT,AT, and PS/2 keyboard,mouse, and game port as response devices in reaction time paradigms

The IBM PC keyboard is a convenient response panel for subjects in a reaction time task when the stimuli are presented on the same machine. However, there is a mean delay of about 10 msec and a random error of ±7.5 msec (±5 msec on the AT or PS/2). Our analyses show that for typical single response experimental situations, this added variance is acceptable. With mouse buttons, timing resulted in a delay of 31 ±2 msec if the mouse ball was steady but 45 ±15 msec if it was moving, and a 25-msec refractory period before a second response could be detected. With keys connected to the game port, timing was accurate to 1 msec. For timing the interval between two nearly simultaneous responses, only the game port method is recommended. Any research application should provide an external check on reaction timing accuracy and should correct any mean error.     

Measuring keyboard response delays by comparing keyboard and joystick inputs

The response characteristics of PC keyboards have to be identified when they are used as response devices in psychological experiments. In the past, the proposed method has been to check the characteristics independently by means of external measurement equipment. However, with the availability of different PC models and the rapid pace of model change, there is an urgent need for the development of convenient and accurate methods of checking. The method proposed here consists of raising the precision of the PC’s clock to the microsecond level and using a joystick connected to the MIDI terminal of a sound board to give the PC an independent timing function. Statistical processing of the data provided by this method makes it possible to estimate accurately the keyboard scanning interval time and the average keyboard delay time. The results showed that measured keyboard delay times varied from 11 to 73 msec, depending on the keyboard model, with most values being less than 30 msec.     

A PC parallel port button box provides millisecond response time accuracy under Linux

For psychologists, it is sometimes necessary to measure peoples reaction times to the nearest millisecond. This article describes how to use the PC parallel port to receive signals from a button box to achieve millisecond response time accuracy. The workings of the parallel port, the corresponding port addresses, and a simple Linux program for controlling the port are described. A test of the speed and reliability of button box signal detection is reported. If the reader is moderately familiar with Linux, this article should provide sufficient instruction for him or her to build and test his or her own parallel port button box. This article also describes how the parallel port could be used to control an external apparatus     

Relative frequency of attribute relevance and response times in visual search

Two experiments, one using a between-Ss and one a within-Ss design, showed that response latencies to single attribute probe stimuli were longer when the target stimulus embodied two attributes (form and color) rather than a single attribute. The magnitude of this "mixed attribute effect" was influenced by the probability of attribute relevance, but the "probability effect" was mostly due to a "repetition effect," such that latencies on trials involving repetitions of the same attribute were shorter than when the relevant attribute was shifted. Implications of these results are drawn for the issues of holistic vs attributized representation of the target stimulus and serial vs parallel search of a set of attributes. Although no class of models can be ruled out on the basis of these experiments, constraints can be imposed on the versions of each that are compatible with the data presented.     

Sequential dependencies and response range in cross-modality matches of duration to loudness

Subjects matched durations of keypresses to loudnesses of pure tones. Resulting duration responses were found to be assimilated to the value of the immediately preceding stimulus and responses from one to at least six trials back in the sequence of loudness stimuli. Responses were contrasted with the values of stimuli two through six trials back in the sequence. These sequential dependencies and other properties of the data were predicted by a cognitive model in which cross-modality matches are mediated by category judgments of stimuli on both continua, and subjects use heuristic strategies to reduce response uncertainty.     

Do you know where your fingers have been? Explicit knowledge of the spatial layout of the keyboard in skilled typists

Two experiments evaluated skilled typists’ ability to report knowledge about the layout of keys on a standard keyboard. In Experiment 1, subjects judged the relative direction of letters on the computer keyboard. One group of subjects was asked to imagine the keyboard, one group was allowed to look at the keyboard, and one group was asked to type the letter pair before judging relative direction. The imagine group had larger angular error and longer response time than both the look and touch groups. In Experiment 2, subjects placed one key relative to another. Again, the imagine group had larger angular error, larger distance error, and longer response time than the other groups. The two experiments suggest that skilled typists have poor explicit knowledge of key locations. The results are interpreted in terms of a model with two hierarchical parts in the system controlling typewriting.     

Amiga 1000 hardware timing and reaction-time key interfacing

A method of hardware reaction timing with millisecond accuracy, using one of the Amiga’s CIA 8520 chips, is described. The registers of this chip can be set to enable cascaded timing that functions independently of the CPU and, thereby, avoids the problems of software timing in a multitasking environment. In addition, the interfacing of a pair of reaction-time keys to one of the Amiga’s game controller connectors and a program for polling this port for keypresses are described.     

An external millisecond timer for the Apple Macintosh with applications to cross-modal lexical priming

The circuit and program described in this report allow researchers to use Macintosh personal computers to conduct research that requires timing with millisecond accuracy. This is accomplished with external response keys and an external clock that sends characters through the Macintosh’s serial port. For researchers interested in cross-modal lexical priming tasks, a tachistoscopic slide shutter is incorporated to allow for accurately timed presentation of visual stimuli. Because the visual display and response keys are external to the computer, display and reaction times are not subject to the timing constraints inherent to the keyboard or the Macintosh Event Manager. All circuit diagrams and code are in the public domain.     

Investigating the role of response in spatial context learning

Recent research has shown that simple motor actions, such as pointing or grasping, can modulate the way we perceive and attend to our visual environment. Here we examine the role of action in spatial context learning. Previous studies using keyboard responses have revealed that people are faster locating a target on repeated visual search displays ("contextual cueing"). However, this learning appears to depend on the task and response requirements. In Experiment 1, participants searched for a T-target among L-distractors and responded either by pressing a key or by touching the screen. Comparable contextual cueing was found in both response modes. Moreover, learning transferred between keyboard and touch screen responses. Experiment 2 showed that learning occurred even for repeated displays that required no response, and this learning was as strong as learning for displays that required a response. Learning on no-response trials cannot be accounted for by oculomotor responses, as learning was observed when eye movements were discouraged (Experiment 3). We suggest that spatial context learning is abstracted from motor actions.     

Investigating the role of response in spatial context learning

Recent research has shown that simple motor actions, such as pointing or grasping, can modulate the way we perceive and attend to our visual environment. Here we examine the role of action in spatial context learning. Previous studies using keyboard responses have revealed that people are faster locating a target on repeated visual search displays (“contextual cueing”). However, this learning appears to depend on the task and response requirements. In Experiment 1, participants searched for a T-target among L-distractors and responded either by pressing a key or by touching the screen. Comparable contextual cueing was found in both response modes. Moreover, learning transferred between keyboard and touch screen responses. Experiment 2 showed that learning occurred even for repeated displays that required no response, and this learning was as strong as learning for displays that required a response. Learning on no-response trials cannot be accounted for by oculomotor responses, as learning was observed when eye movements were discouraged (Experiment 3). We suggest that spatial context learning is abstracted from motor actions.     

Effects of response eccentricity and relative position on orthogonal stimulus-response compatibility with joystick and keypress responses

When unimanual left-right movement responses are made to up-down stimuli, performance is better with the up-right/down-left mapping when responding in the right hemispace and with the up-left/down-right mapping when responding in the left hemispace. We evaluated whether this response eccentricity effect is explained best in terms of rotational properties of the hand (the end-state comfort hypothesis) or asymmetric coding of the stimulus and response alternatives (the salient features coding hypothesis). Experiment 1 showed that bimanual keypresses yield a response eccentricity effect similar to that obtained with unimanual movement responses. In Experiment 2, an inactive response apparatus was placed to the left or right of the active response apparatus to provide a referent. For half of the participants, the active and inactive apparatuses were joysticks, and for half they were response boxes with keys. For both response types, an up-right/down-left advantage was evident when the relative position of the active response apparatus was right but not when it was left. That bimanual keypresses yield similar eccentricity and relative location effects to those for unimanual movements is predicted by the salient features coding perspective but not by the end-state comfort hypothesis.     

Computer program for standardization of curriculum-based probes

This computer program will compute standard scores with any desired mean and standard deviation. The program requires the user to enter the raw scores of each member of the sample to be standardized. The program accepts input from the computer keyboard, stores data in files on a floppy disk, and produces output on the printer.     

SuperLab: General-purpose Macintosh software for human experimental psychology and psychological testing

SuperLab is a general-purpose psychology testing package for the Macintosh. SuperLab presents static visual and auditory stimuli in blocks of trials, each trial consisting of a user-specified sequence of stimuli. Responses can be recorded from the keyboard or from switches connected to an I/O board. Stimuli can be contingent on subjects’ responses, allowing feedback based on response accuracy. Timing uses Time Manager routines from the Macintosh Toolbox. Data are recorded in a text format with tabs delimiting fields, allowing analysis and presentation by other Macintosh spreadsheet, statistics, and graph-making applications. SuperLab has a Macintosh user interface for developing experiments. Psychological tasks can also be designed and modified with any application that generates a text format file.     

Voice recognition with the Apple-Psych system

Use of the IntroVoice I voice recognition board with the Apple-Psych system is described. The device augments the EF ROM, keyboard ROM, and keyboard encoder chip in Apple II series computers and provides speaker-dependent recognition of up to 80 words. IntroVoice II, an upgrade, can recognize up to 160 words. Since the operation of IntroVoice is software-transparent, the Apple-Psych system recognizes the board’s output as console (keyboard) input, making it useful as a response collection device. The keyboard continues to operate normally, in parallel with voice recognition. Problems and solutions for response recognition and timing are discussed, and illustrative experimental data are presented.     

Effect of an initiating action on the up-right/down-left advantage for vertically arrayed stimuli and horizontally arrayed responses

When up and down stimuli are mapped to left and right keypresses or "left" and "right" vocalizations in a 2-choice reaction task, performance is often better with the up-right/down-left mapping than with the opposite mapping. This study investigated whether performance is influenced by the type of initiating action. In all, 4 experiments showed the up-right/down-left advantage to be reduced when the participant's initiating action was a left response compared with when it was a right response. This reduction occurred when the initiating action and response were both keypresses, both were spoken location names, and one was a spoken location name and the other a keypress. The results are consistent with the view that the up-right/down-left advantage is due to asymmetry in coding the alternatives on each dimension, and a distinction between categorical and coordinate spatial codes seems to provide the best explanation of the advantage.     

Item characteristics that predict response latency in personality measures

This study assesses some item characteristics that are expected to affect response latencies in the computerized administration of a personality questionnaire. First, some previous empirical results are discussed, and a theoretical framework from which predictions can be made is proposed. Second, the predictions are empirically assessed using two data-sets, one of them based on binary items, and the other one based on graded-response items. Some of the results obtained are new, whereas the remaining agree with previous empirical results. The implications of the present results in applied research, and particularly for the use of latencies, is discussed.