Multilevel models in developmental psychological research: Rationales and applications

The armoury of statistical techniques has recently been enhanced with the multilevel model for longitudinal data. The present article explains the multilevel model for longitudinal data to the statistically non-sophisticated reader. It shows how the model relates to the five rationales of longitudinal research, as they were put forward by Baltes and Nesselroade (1979). In addition, it shows how the model matches Wohlwill's methodology of developmental functions. To elucidate the model further, three applications are given. The applications pertain to the development of children's sleeping duration during the first 18 months of life, the effects of early hospitalization on the daily frequency of crying, and the developmental relationship between social and solitary play.     

A tether system for cardiovascular studies with the behaving micropig

A tether system has been developed for continuous monitoring of blood pressure in the micropig. The micropig is a suitable model for blood-pressure research because of the similarity of its cardiovascular system to that of humans and because of its sensitivity to high sodium intake. The system consists of a metal boom, attached via a universal joint to a wall 6 ft above floor level, that extends horizontally to the center of the enclosure. A fluid and electronic swivel affixed to the boom is connected to a flexible, hollow, metal tether that descends to a vest worn by the micropig. The vest contains a pressure transducer to which an indwelling arterial catheter is connected via a stopcock. The transducer cable and an infusion line ascend through the interior of the tether to the swivel. The system remains in equilibrium through a system of pulleys and counterweights. Continuous, 24-h recording shows a diurnal variation characterized by higher heart rate but lower blood pressure during the day than at night. The system has been found to be effective for continuous studies over intervals of a month or more.     

Picture Perception Lab: A program for picture perception experiments on the Macintosh II

Picture Perception Lab (PPL) is a program for picture perception experiments. PPL capitalizes on the sophisticated drawing software available for the Macintosh computer by allowing the user to create stimulus images by using almost any drawing package. Through a series of user-friendly dialog boxes, PPL enables even nonprogrammers to develop, quickly and easily, tachistoscopelike vision experiments. The program allows a wide variety of experimental designs. Image exposure durations and subjects’ reaction times are precisely monitored with millisecond timing functions. Each image is drawn on the screen in a single 60-Hz refresh.     

Convergent methods in psychomusical research based on integrated,interactive computer control

Much of what we learn from an experiment depends on what we ask of the subjects and how we ask it. Most music perception and cognition research is implemented using a single methodology. Recently, questions have been raised about the validity and generalizability of such a limited approach, particularly regarding such complicated theoretical constructs as musical tonality. We propose that a useful technique is to converge on the answer to experimental questions by applying multiple methods, in essence, simultaneously investigating the central research question as well as ancillary questions of method. Such an approach is facilitated by a computer hardware and software system that integrates experimental design, data collection, data analysis, and data dissemination, linking off-the-shelf components through standard file formats and data-exchange protocols. The list-based system, using an IBM-type PC running Windows 3.0, handles real-time natural sound sampling and playback, signal synthesis and analysis, MIDI input and output, digitized picture display, and various subject-response mechanisms. On the basis of graphical icons, the integrated system can be used to build custom experimental designs. Examples of convergent psychomusical experiments that were designed, implemented, and analyzed using the system are discussed.     

Technologies to reliably transduce the topographical details of pigeons’ pecks

Pigeons’ pecking has long been a subject of interest in behavioral research, with the response typically being viewed as unitary. Recent experiments done with computer-controlled devices have revealed that this response is at least bipartite in character, with beak opening and response location (head transport) as its components. In addition, experimental work has demonstrated that these response components may be separately influenced and controlled by respondent and operant conditioning procedures. The detailed topographic analysis and technology that have emerged may provide a background for similar work with other behavioral systems.     

Data generation and analysis using spreadsheets

Modern spreadsheets are powerful and useful tools that can often replace special-purpose programs for generating data and for student analysis of simple statistical problems. The inherent flexibility of spreadsheets makes them especially convenient and extensible. Several templates for generating and analyzing data fort tests and analysis of variance are discussed. Users can specify then, \(\bar X\) , andSD of two or more groups and then execute macros that generate appropriate data. Overwriting the generated data with “real” values turns the spreadsheet into a data analysis program. Spreadsheets hold promise as valuable instructional supplements for simple designs, but they are less suitable for more complex designs, where special-purpose programs may be more appropriate.     

Using tutoring systems to study learning: An application of HyperCard

HyperCard was used to develop a simplified tutoring system whose principles were based on a learning theory, and a genetics tutoring system was evaluated experimentally. Learning was studied by examining immediate versus delayed feedback after an error was made. Such tutoring systems aid in psychological studies of learning, because experimental variables can be easily manipulated. HyperCard provides a good vehicle for tutoring system development, since it requires no extensive programming skills.     

Analysis of periodic data using Walsh functions

Data often contain periodic components plus random variability. Walsh analysis reveals periodicities by fitting rectangular functions to data. It is analogous to Fourier analysis, which represents data as sine and cosine functions. For many behavioral measures, Fourier transforms can produce spurious peaks in power spectra and fail to resolve separable components. Walsh analysis is superior for strongly discontinuous data. The strengths and weaknesses of each transform are discussed, and specific algorithms are given for the newer Walsh technique.     

GRADER: A computer program that recommends student letter grades

GRADER, a computer program that makes student test and/or course letter grade recommendations to instructors, is described. The program uses an algorithm to combine the content mastery (percentage correct) and peer comparison (“curve”) approaches to set grade cutoffs. In addition to standardizing the procedures with which letter grade cutoffs are made, GRADER may help to reduce instructor grading subjectivity and obviate tendencies toward grade inflation or deflation.     

Representation of on-line questionnaires in an editable,auditable database

A general way of describing multiple-choice questionnaires for on-line presentation is described. Some of the important features supported include random ordering of and sampling among questions, substitution of specific-question text into boilerplate question and response formats, a limited ability to bypass irrelevant questions, experimenter editing of response arrays, and automatic production of hard-copy versions of the questionnaire for use during computer breakdowns and for archival documentation. All editing operations on both questionnaires and response data create audit trails for future reference.