EFFECTS OF PRESENTATION METHOD ON ACQUISITION SPEED OF AN IDENTITY MATCHING-TO-SAMPLE TASK A Thesis Presented to the Faculty of California State University, Stanislaus In Partial Fulfillment of the Requirements for the Degree of Master of Science in Psychology By Amanda McCullough December 2014
CERTIFICATION OF APPROVAL EFFECTS OF PRESENTATION METHOD ON ACQUISITION SPEED OF AN IDENTITY MATCHING-TO-SAMPLE TASK By Amanda McCullough Signed Certification of Approval Page is on file with the University Library Dr. Bruce E. Hesse Professor of Psychology Date Dr. William F. Potter Professor of Psychology Date Dr. Carrie M. Dempsey Professor of Psychology Date
2014 Amanda McCullough ALL RIGHTS RESERVED
DEDICATION I dedicate this fully completed thesis to all who supported me along this journey. I dedicate this thesis to my grandma and papa, whose unconditional love, serious and humorous discussions, and of course weekly dinners, gave me strength to complete this intimidating task. I dedicate this thesis to my dad who tolerated my books, papers, and my computer taking over the dining room table for the past year. I dedicate this thesis to my mom, for all the love and support throughout this project, as well as listening to me ramble on about it for way too many years. The principles you instilled in me, when I was young, lead me to believe that college was not a choice, but a requirement, and it has brought me this far. I dedicate this thesis to my sisters, my brother-in-law, and Ted for keeping me sane with extracurricular activities. Without summer barbecues, babysitting my niece and nephew, and watching San Francisco Giants games, I don t know if I would have completed this thesis. I dedicate this thesis to my aunt Lana, whose discussions about being a strong and independent woman gave me the drive to accomplish this thesis. I dedicate this thesis to my friend Tasha, for not only being my supportive lifetime friend, but for joining me in the lab the one time a pigeon escaped the cage and I had to catch it. I dedicate this thesis to my boyfriend Andrew, for his assistance on the first day in the lab with the pigeons and his encouraging and kind words of support throughout the past two years. iv
I dedicate this thesis to all my family and friends who lost time with me while I spent hours/days/weeks researching and writing. All the text messages and phone calls asking if I was working on my thesis lead up to this finished product. v
ACKNOWLEDGEMENTS I would like to thank my thesis committee chair, Dr. Hesse, for all his time assisting in the selection of my thesis topic, the edits to my written work, tolerating my numerous emails, and for the assistance in the lab with the pigeons. Thank you to my committee members, Dr. Potter and Dr. Dempsey, whose knowledge and expertise assisted in the completion of this thesis. I would also like to thank all my psychology professors whose ability to teach effectively contributed to this thesis completion. I would like to thank Mila, Katherine, Kelly, Cathy, Aubrie, Denise, Kirsten, and Kym, for their supervision at Central Valley Autism Project. I would also like to thank all my colleagues at CVAP. Through working at CVAP, I discovered my passion for behavior analysis, before I even knew what it was, and ultimately was inspired to complete my Master s degree. I also must thank Angie for coming into my psychology 101 class at MJC in 2003 and making this thesis a possibility. Thank you to all who have inspired me to obtain my Master s degree and become a behavior analyst. vi
TABLE OF CONTENTS PAGE Dedication... Acknowledgements... List of Tables... List of Figures... Abstract... iv vi ix x xi Literature Review... 1 Matching-to-sample... 1 Presentation Methods of Comparison Stimuli... 3 Simultaneous Presentation... 3 Successive Presentation... 4 Research on Successive and Simultaneous Presentation Methods... 5 Acquisition... 8 Mastery Criterion... 9 Trial... 9 History of Acquisition... 10 Mastery Criterion in Past Research... 10 Measures of Acquisition Speed in Past Research... 11 Additional Variables to Consider... 12 Serial vs. Non-serial... 12 Presence/Absence of the Sample Stimulus... 13 Other Variables... 14 Implications for Further Research on Acquisition Speed... 15 Conclusion & Hypotheses... 18 Methodology... 19 Subjects... 19 Apparatus/Stimuli... 19 Experimental Design... 20 Procedure... 20 Preliminary Training... 20 Matching Procedure... 21 Simultaneous Matching Condition... 21 Successive Matching Condition... 22 Dependent Variables... 24 vii
Results... 25 Preliminary Training... 25 Matching Procedures... 25 Discussion... 33 Limitations... 34 Suggestions for Future Research... 38 Conclusion... 41 References... 44 viii
LIST OF TABLES TABLE PAGE 1. Color selection... 20 2. Trials to criterion... 26 ix
LIST OF FIGURES FIGURE PAGE 1. Bird # 99 percentage of correct trials by color and condition... 27 2. Bird #99 cumulative trials to criterion... 27 3. Bird #75 percentage of correct trials by color and condition... 28 4. Bird #75 cumulative trials to criterion... 29 5. Bird #74 percentage of correct trials by color and condition... 30 6. Bird #74 cumulative trials... 30 7. Bird #61 percentage of correct trials by color and condition... 31 8. Bird #61 cumulative trials... 32 x
ABSTRACT Research has demonstrated the acquisition speed of a skill/behavior may be altered by a large quantity of variables. In this research, acquisition speed was measured to determine which method of presentation of the comparison stimuli resulted in the fastest acquisition of a matching-to-sample task. Four pigeons were trained on an identity matching-to-sample task, with simultaneous presentation of comparison stimuli and successive presentation of comparison stimuli. An alternating treatments design was utilized. Results indicated that, although pigeons acquired the matchingto-sample task in both the simultaneous and the successive presentation methods, they acquired the task more quickly when the comparison stimuli were presented simultaneously. Implications for future research with regard to selecting the presentation method to increase acquisition speed, maintenance, and generalization are discussed. xi
LITERATURE REVIEW Matching-to-sample Matching-to-sample (MTS) is a procedure used throughout behavior analytic research to study a variety of complex learning variables. It typically involves the presentation of a sample stimulus, of which an observing response is required for presentation of the comparison stimuli, followed by either selection of the matching comparison stimulus, which results in presentation of a positive reinforcer, or selection of the non-matching stimulus, which results in no reinforcer, while the sample stimulus remains present (Cooper et al., 2007, p. 399; Cumming & Berryman, 1961; Pierce & Cheney, 2008, p. 185). There are two basic types of MTS: identity MTS and arbitrary MTS (also known as symbolic MTS). In identity MTS, the subject s choice-response must be based on some common property of the sample and comparison stimuli (Berryman et al., 1963, p. 101). For example, identity MTS could involve identically matching stimuli, such as matching the color red to the color red, or it could involve matching stimuli that are only partially similar, such as matching the letter b to a word that starts with the letter b. In arbitrary MTS, the subject s choice-response is based on an arbitrary relation between two classes of stimuli (Pierce & Cheney, 2008). For example, arbitrary MTS could involve matching a form to a color, such as matching circles to the color red and squares to the color blue. The basic format of MTS was outlined with detail by Cumming and Berryman in 1961 and has since been utilized throughout the literature. 1
2 The basic matching-to-sample (MTS) format, as outlined by Cumming and Berryman (1961) has been used to evaluate the acquisition of a variety of skills/behaviors, as well as to evaluate the potential impact of other variables on the success of an organism learning a MTS task. One clarification must be made with regard to MTS. In 1963, Berryman et al. described MTS as a conditional discrimination because the success of matching is based on a response to two stimuli. However, Pierce and Cheney (2008) state that conditional matching to sample involves simultaneous discrimination of three elements in a display. As an example Pierce & Cheney state that [t]he animal must respond to geometric form depending on the background color of the sample. It also must respond to the correspondence or non-correspondence of the comparison stimuli. It seems further clarification of a conditional discrimination is necessary since previous research is unclear. For the present study, MTS will not be referred to as being a conditional discrimination. Further research is also warranted to evaluate the effects of the manipulation of complex learning variables on the acquisition of skills/behaviors taught with the MTS procedure outlined by Cumming and Berryman in 1961. Understanding the interactions of variables may allow identification of combinations which may produce ideal results with regard to learning. Variables such as the delay of the presentation of the comparison stimuli, the presentation of the comparison stimuli being successive or simultaneous, the presence or absence of the sample stimulus, intertrial intervals, retention intervals, sample stimulus duration, reinforcement schedules, prefeeding, response-independent food, the number of exemplars trained, the type of
3 exemplars trained, and any variety of combination of these variables may provide useful information for understanding the processes involved in learning (Pierce & Cheney, 2008). Additionally, Berryman et al. 1963 recommended further research to clarify the effects of possible position preferences, color preferences, and the pigeons use of repetitive chains on the learning of a MTS task. Samuels (1969) recommended further research to identify the effects of stimulus similarity on the acquisition of MTS. The present study will evaluate the presentation style of the comparison stimuli while controlling for additional variables. Presentation Methods of Comparison Stimuli Research utilizing the basic matching-to-sample (MTS) format has evaluated the effects of the simultaneous and the successive presentation of the comparison stimuli on the acquisition of skills/behaviors. Simultaneous Presentation Simultaneous presentation of the comparison stimuli is defined as the sample stimulus and the comparison stimuli being presented at the same time (Butter & Snyder, 1982; Cumming & Berryman, 1961; Cuvo et al., 1980; Jeffrey, 1961; Loess & Duncan, 1952; Samuels, 1969; Pierce & Cheney, 2008). The simultaneous presentation has been used in teaching basic discriminations and matching-to-sample tasks involving a variety of concepts. It has been used to teach basic discrimination of circle sizes by rats, identification of people by pigeons, and shapes, blocks, colors, and object names to humans (Baker & Lawrence, 1950; Cuvo et al., 1980; Grice, 1948; Jeffrey, 1961; Lipsitt, 1961; Loess & Duncan, 1952; Malott & Siddall, 1972).
4 It has been used to teach matching-to-sample of colors, lines, and cartoons to pigeons, and colors, letters, and familiar figures to humans (Berryman et al., 1963; Bodily et al., 2008; Butter & Snyder, 1982; Cumming & Berryman, 1961; Cumming et al., 1965; Farthing & Opuda, 1974; Ferster, 1960; Nevin et al., 2003; Samuels, 1969). Successive Presentation Successive presentation of the comparison stimuli is defined as the sample stimulus being presented on one key, followed by the presentation of the comparison stimuli being presented independently of the other (one at a time), on a separate key, and the participant differentially responds to the single stimulus (Baker & Lawrence, 1950; Butter & Snyder, 1982; Cuvo et al., 1980; Grice, 1948; Jeffrey, 1961; Lipsitt, 1961; Loess & Duncan, 1952; Nelson & Wasserman, 1978; Pierce & Cheney, 2008; Samuels, 1969). Successive presentation of the comparison stimuli has been used to teach basic discrimination tasks and matching-to-sample tasks. It has been used to teach basic discriminations of circle sizes to rats, pictures of trees to pigeons, and shapes, sizes, blocks, colors, and object names to humans (Baker & Lawrence, 1952; Cuvo et al., 1980; Grice, 1948; Herrnstein, 1979; Jeffrey, 1961; Lipsitt, 1961; Loess & Duncan, 1952). It has also been used to teach matching-to-sample of colors to pigeons and with the Matching Familiar Figures Test with humans (Butter & Snyder, 1982; Nelson & Wasserman, 1978). Research on Successive and Simultaneous Presentation Methods The research on successive and simultaneous presentation methods has provided insight to the acquisition of a variety of skills/behaviors. A review of the
5 literature found that basic discrimination tasks and matching-to-sample tasks have been acquired by rats, pigeons, and humans with both presentation methods of the comparison stimuli (Baker & Lawrence, 1951; Berryman et al., 1963; Butter & Snyder, 1982; Cumming et al., 1965; Grice, 1948; Jeffrey, 1961; Lipsitt, 1961; Loess & Duncan, 1952; Samuels, 1969; Thomas et al., 1990). This body of research provides information that identifies which presentation method, in combination with other variables; is most likely to produce the best outcomes with regard to acquisition of skills/behaviors. In 1948, Grice taught rats to discriminate between different sizes of circles, with the simultaneous and successive presentation of comparison stimuli. The research found that the rats learned the discrimination task in both conditions. Grice concluded that the basic processes involved are the same whether the stimuli are simultaneously present or not. There is also research supporting the acquisition of discrimination of blocks, colors, and shapes and sizes, in humans, with simultaneous presentation and successive presentation of the comparison stimuli (Jeffrey, 1961; Lipsitt, 1961; Loess & Duncan, 1952). Additionally, research by Butter & Snyder in 1982 demonstrated that humans taught with the comparison stimuli presented simultaneously or successively, resulted in acquisition of the Matching Familiar Figures Test. In 1990, Thomas et al. researched the acquisition of arbitrary matching-to-sample task of colors and lines, with the simultaneous presentation of the comparison stimuli and the successive presentation of the comparison stimuli. It was found that both conditions resulted in the acquisition of the task. Though several studies have been conducted analyzing the presentation
6 method of the comparison stimuli, inconsistencies and gaps in the research remain present. The use of the terms successive and simultaneous have been used and defined inconsistently throughout the literature. Berryman et al. (1963), Cumming et al. (1965), and Samuels (1969) defined successive presentation and simultaneous presentation with regard to the presence or absence of the sample stimulus when the comparison stimuli are presented. This definition is contradictory to other research. In most of the research on the topic, simultaneous presentation of the comparison stimuli is defined as the discriminative stimulus and the S-delta being presented at the same time (Butter & Snyder, 1982; Cumming & Berryman, 1961; Cuvo et al., 1980; Jeffrey, 1961; Loess & Duncan, 1952; Samuels, 1969; Pierce & Cheney, 2008). For the purpose of the present study, the latter definition will be utilized, such that the successive presentation method will be defined as each of the two comparison stimuli being presented individually, and the simultaneous presentation method will be defined as both of the comparison stimuli being presented together. Along with inconsistent use of the terminology, there have been inconsistent controls for extinction effects when comparing the two presentation methods of the comparison stimuli. Problems have been demonstrated with the successive presentation of comparison stimuli when not providing reinforcement for an inhibitory response to incorrect matches. The acquisition of the skill being taught takes longer, and errors continue after mastery is achieved, due to the extinction burst that typically occurs (Pierce & Cheney, 2008, p. 182). Therefore further research
7 controlling for extinction effects is warranted. For the present study, this will be controlled by providing access to reinforcement for a response to the matching comparison stimulus following a response to a changeover stimulus (white, nonmatching key) in the successive presentation condition. Providing the opportunity for access to reinforcement for every trial in the successive condition provides equal opportunities for access to reinforcement between the successive and simultaneous presentation conditions. In addition to consistent use of terminology and control for extinction effects, further research is indicated as necessary to determine additional variables that may impact the acquisition of the MTS task. Though most of the literature revealed the successful acquisition of discrimination tasks and MTS tasks, Berryman et al. (1963) demonstrated that the MTS task was not acquired when simultaneous presentation of the comparison stimuli, with or without the sample stimulus present was utilized. It was concluded that pigeons did not learn a matching-to-sample task. However, Cumming et al. (1965) and Samuels (1969) found that the matching-to-sample task was acquired when using the same methods. Analyses of the two studies showed the potential difference between the studies may be that Berryman et al. used a delayed matching-to-sample task which included several variations of delays (1, 2, 4, 10, and 24 seconds) between the offset of the sample to the presentation of the comparison stimuli, and Cumming et al. and Samuels used zero-delay. To control for the possible negative effects of increases in the delay of presentation of the comparison stimuli on
8 the acquisition of the MTS task, the present research will keep the sample stimulus present across both presentation methods. The literature review also revealed that there are numerous possible combinations of variables which may affect the acquisition of a MTS task, when utilizing the successive and simultaneous presentation methods, which have not been evaluated. With numerous variables held constant, only one research study utilized MTS to truly compare the simultaneous presentation of the comparison stimuli to the successive presentation of the comparison stimuli in humans (Butter & Snyder, 1982). Other research utilized simple discrimination tasks to compare the two presentation methods, across at least five research studies in humans and non-human subjects (Baker & Lawrence, 1950; Grice, 1948; Jeffrey, 1961; Lipsitt, 1961; Loess & Duncan, 1952). A solid comparison of the presentation methods is warranted, and may reveal which presentation method results in the best outcome in terms of the speed of acquisition of skills/behaviors. The present study will compare the acquisition of the MTS task of the two presentation methods, while holding many additional variables constant and/or controlling for potential confounding variables. Acquisition Acquisition speed has been used in past research to evaluate the impact of variables on skills/behaviors taught using MTS. The rate of development of a skill/behavior has been referred to as the acquisition speed or rate of acquisition. In the literature, acquisition speed has been measured by evaluating trials-to-criterion.
9 Trials-to-criterion data are used frequently to compare the relative efficiency of two or more treatments or instructional methods (Cooper, 2007, p. 82). Trials-tocriterion is a measure of the number of response opportunities needed to achieve a predetermined level of performance (Cooper et al., 2007, p 82). The predetermined level of performance is also known as the mastery criterion. Mastery Criterion The mastery criterion is a predetermined criterion within training according to the performance of people judged to be highly competent (Cooper et al., 2007, p.69). The most frequently used mastery criterion within the literature is the measure of the percentage of correct responses. Once the mastery criterion is reached, then the skill/behavior is considered acquired. Once the skill/behavior is acquired, then it is possible to measure the speed of acquisition (calculated as the number of trials-tocriterion). Trial To ensure an accurate comparison of acquisition speed, a trial must be clearly, appropriately, and consistently defined. Loess and Duncan (1952) defined a trial as the presentation of either a pair of stimuli, or a single stimulus, and a subsequent differential response by the S (p. 220). The opportunity to access reinforcement whether the discriminative stimulus is present or an s-delta is present is critical to ensuring accurate comparisons of acquisition speed. Utilizing this definition of a trial, allows for trials-to-criterion to accurately compare the efficiency of learning a
10 MTS task which is taught by successively presenting the comparison stimuli to a MTS task which is taught by simultaneously presenting the comparison stimuli. History of Acquisition Comparisons of trials-to-criterion have been used, in previous research, to determine the speed of acquisition of skills/behaviors taught with the simultaneous or successive presentation of the comparison stimuli in combination with additional variables. Review of the literature revealed inconsistencies with set mastery criterion and the measurements used to compare acquisition speed, within and across populations. Mastery Criterion in Past Research Mastery criterion has been set at various levels using various measurement tools within research utilizing the MTS procedure. With rats, the mastery criterion that has been used within the literature includes achievement of 90% for a specified minimum number of trials (Baker & Lawrence, 1950; Grice, 1948). With pigeons, the mastery criterion that has previously been used includes achievement of an increase in the overall range from above chance (50%) accuracy to 90% across trials/sessions (Towe, 1951), achievement of above chance accuracy (Cumming, 1961; Nelson & Wasserman), achievement of 75% accuracy (Berryman et al., 1963; Cumming et al., 1965), achievement of five consecutive correct trials for each example (Malott & Siddall, 1972), and the achievement of 85% or greater accuracy for 2 consecutive sessions (Bodily et al., 2008). With humans, the mastery criterion that has been used within the literature includes the achievement of an increase in the
11 overall range from above chance (50%) accuracy to 100% across 90% of the trials/sessions/days (Spiker, 1956), achievement of ten consecutive correct trials (Jeffrey, 1961), achievement of nine consecutive correct trials (Lipsitt, 1961), achievement of above chance performance overall (Samuels, 1969), and achievement of 90% across two instructors and two sessions (Weiss, 1999). The mastery criterion set in previous research led to the conclusion that the most appropriate mastery criterion, which will be used in the present study, is 80% accuracy for two consecutive sessions. Measures of Acquisition Speed in Past Research Once a consistent and appropriate mastery criterion is set, then the acquisition speed of a skill/behavior can be determined. Acquisition speed is a measurement from the onset of training to the set mastery criterion, and in past research it has been measured using various measurement tools, across populations. The most commonly used measurement of acquisition speed has been the number of trials to meet the mastery criterion (Baker & Lawrence, 1950; Berryman et al., 1963; Bodily et al., 2008; Cumming et al., 1965; Grice, 1948; Jeffrey, 1961; Lipsitt, 1961; Loess & Duncan, 1956; Malott & Siddall, 1972; Panyan & Hall, 1978; Samuels, 1969; Towe, 1951). Combinations of the number of errors and the number of trials to criterion have been used to compare the speed of acquisition of skills/behaviors with humans and pigeons (Malott & Siddall, 1972; Spiker, 1956). Other measures used, with pigeons, include the level of chance responding (Cumming & Berryman, 1961; Thomas et al., 1980), number of sessions to criterion (Farthing & Opuda, 1974), and
12 the rate of responding (Blough, 1979; Herrnstein, 1979; Nelson & Wasserman, 1978). Research has also measured acquisition speed of skills/behaviors, with humans, by calculating the amount of training time and the number of trials to criterion (Cuvo et al., 1980), the number of errors and the latency to responding (Butter & Snyder, 1982), and the number of days to mastery criterion (Weiss, 1999). The present study will measure acquisition speed by calculating the number of trials to criterion as it is the most consistently used measure across all populations. Additional Variables to Consider Previous research has shown that the differences in acquisition speed, of skills/behaviors taught within basic discrimination tasks and MTS tasks, which include the simultaneous and successive presentation styles of the comparison stimuli, may be attributed to numerous variables, across populations. Serial vs. non-serial. The speed of acquisition may be impacted by the teaching methods which may be utilized; serial and non-serial. A review of the literature revealed that serial teaching has not been utilized in teaching a MTS task; however, it has been used in the teaching of a basic discrimination task. Serial teaching is defined as criterion performance being required on each discrimination item before the next item is introduced (Malott & Siddall, 1972; Panyan & Hall, 1978). Therefore if the concept of colors is being taught, then the color red may be taught to mastery before the color blue is taught, and so on. Non-serial teaching differs from serial teaching because a different discrimination problem is presented on each trial (Malott & Siddall, 1972). Therefore, if the concept of colors is being
13 taught, then all colors being taught are presented interchangeably until they all reach mastery. In 1978, Panyan & Hall compared serial and non-serial teaching of two tasks, tracing and vocal imitation, with humans, and concluded that the skills were acquired with both teaching methods. Panyan & Hall did not compare the acquisition speed of the serial and non-serial teaching methods. Cuvo et al. (1980) compared the discrimination of object names when taught serially with the successive presentation of stimuli to being taught non-serially with the simultaneous presentation of stimuli with humans. It was concluded that non-serial teaching with simultaneous presentation of the stimuli resulted in a slower speed of acquisition than serial teaching with successive presentation of the stimuli. The present research will utilize the non-serial teaching method for teaching the MTS task, as that is the method typically used within MTS. Presence/absence of the sample stimulus. Another variable which may impact the speed of acquisition, within MTS, is the presence or absence of the sample stimulus during the presentation of the comparison stimuli. In Cumming and Berryman s (1961) basic MTS format, the sample stimulus remains present at the time that the comparison stimulus (or stimuli) are presented. This format has been consistently used throughout the research on MTS. The presence of the sample stimulus has been used to teach colors, forms, and objects to pigeons, and to teach letters and with the Matching Familiar Figures Test with humans (Bodily et al., 2008; Butter & Snyder, 1982; Cumming, 1961; Cumming et al., 1965; Farthing & Opuda 1974; Samuels, 1969). Research has also evaluated acquisition speed while the
14 sample stimulus was absent. Berryman et al. (1963) and Cumming et al. (1965) explained that when the participant does not have the sample stimulus present at the time that the differential response is made to the comparison stimuli, it is labeled the zero-delay procedure. Matching-to-sample with the absence of the sample stimulus has been used in teaching a variety of concepts to pigeons and humans. It has been used to teach colors and lines to pigeons, and letters to humans (Berryman et al., 1963; Cumming et al., 1965; Ferster, 1960; Nelson & Wasserman, 1978; Nevin et al., 2003; Samuels, 1969). With pigeons and humans, the acquisition of a MTS task with the sample stimulus present resulted in faster acquisition than when the sample stimulus was absent (Berryman et al., 1963; Cumming et al., 1965; Samuels, 1969). The present research will keep the sample stimulus present during presentations of comparison stimuli. Other variables. Research on acquisition speed has also evaluated and/or discussed the influence of the influence of additional variables. Towe (1951) found that if the brightness of the stimuli was altered from the training level then pigeons favored the stimuli with the original level of brightness. In 1961, Cumming found that some pigeons demonstrated a preference for specific colors of the stimuli. In 1968, Eckerman et al. found that an observing response to the sample stimulus was necessary for the pigeons to acquire the task. Jeffrey (1961) concluded it is easier for humans to acquire a discrimination task when it is learned by making a response choice between inhibition and response rather than when making a choice between two responses. Spiker (1956), Lipsitt (1961), and Farthing and Opuda (1974) found
15 that higher similarity between stimuli resulted in slower acquisition speed. Farthing and Opuda also found that tasks with forms resulted in slower acquisition than tasks with colors. Research has found that the duration of presentation of the sample stimulus does not have an effect on acquisition of the task, however increased duration of the intertrial interval demonstrated faster acquisition than smaller intertrial intervals (Neslon & Wasserman, 1978). Herrnstein (1979) discussed the possible differences of acquisition between 3d and 2d stimuli. Finally, Blough (1979) and Bodily et al. (2008) found that increasing the amount of comparison stimuli resulted in slower acquisition speed. The present study will attempt to control for each of these variables in order to allow a true comparison of the acquisition speed of the simultaneous and successive presentation methods. Implications for Further Research on Acquisition Speed The review of the literature on acquisition speed revealed inconsistencies, gaps, and contradictions. There are contradictions in the research findings with regard to the potential confounding variables, such as position preferences, sample stimulus durations, and the number of comparison stimuli. Cumming and Berryman (1961) and Berryman (1963) found that there was not a position preference; however Cumming et al. (1965) found that there was a position preference with MTS tasks. Nelson and Wasserman (1978) found that increasing the duration of the sample stimulus did not affect learning; however Farthing and Opuda (1974) found that changes did affect
16 learning. In 1979, Blough found that an increased number of comparison stimuli decreased the acquisition speed; however, in 2008, Bodily et al. found that the increases did not change acquisition speed. Contradictory results have been reported within basic discrimination tasks comparing the successive and simultaneous presentation methods. Jeffrey (1961) and Lipsitt (1961) demonstrated, with humans, that the simultaneous presentation of the discriminative stimulus and the s-delta resulted in faster acquisition of the task than when they were presented successively. However, Loess and Duncan (1952) concluded that the task was learned with equal speed, unless other variables were manipulated. The present study will control for potential position preferences, present the sample stimulus for a consistent duration, and provide a consistent amount of sample stimuli across all conditions. Lutzker and Sherman 1974 (as cited in Cuvo et al. 1980) referred to the teaching of the names of stimuli one at a time as the successive presentation method. However, Malott and Siddall (1972) and Panyan and Hall (1978) defined criterion performance required on each discrimination item before the next item is introduced as being serial presentation. Further clarification and consistent use of the terminology is warranted. To ensure the correct identification of the condition which results in the fastest acquisition speed, Lutzker and Sherman s definition of the successive presentation method will not be utilized in the present study. The present study will present all stimuli non-serially; meaning all the stimuli will be taught concurrently.
17 Additionally, the term successive will be used to identify the condition in which one comparison stimulus is presented at a time. Only one MTS study has demonstrated a difference in acquisition speed between the successive and simultaneous presentation of the comparison stimuli. Butter and Snyder (1982) found that, in humans, the acquisition of a MTS task, with simultaneous presentation of the comparison stimuli was faster than when the comparison stimuli were presented successively. Mastery criterion was not set in this study; subjects were all exposed to equal amounts of stimuli. The acquisition of the successive and simultaneous presentation styles was compared by measuring the number of errors and the latency of responding. Butter and Snyder also counterbalanced the two groups by exposing all subjects to both the simultaneous and successive test conditions. It was found that subjects who were exposed to the simultaneous presentation style prior to the successive presentation style demonstrated less errors than those exposed to the successive presentation method first. Further research is warranted to confirm these findings, across populations. The present study will evaluate the differences in acquisition speed between the successive and simultaneous presentation methods with pigeons. Research on speed of acquisition should utilize a clear, accurate, and appropriate definition of a trial, identify appropriate and consistent mastery criterion, utilize consistent measurement methods, control for potential confounding variables, utilize consistent terminology for presentation methods, as well as replicate previous
18 research, to ensure accurate, valid, and reliable results; all of which the present study will attempt to address. Conclusions & Hypotheses To conclude, matching-to-sample (MTS) has been used to study the variables in the process of learning. Manipulating the variables may reveal information about the acquisition speed of formally taught skills/behaviors. A comparison of the successive and simultaneous presentation of the comparison stimuli within a MTS task is warranted. For an accurate comparison, consistent definitions of the terminology, appropriate mastery criterion, and control of potential confound variables is needed. The present study will evaluate the acquisition speed of a matching-to-sample (MTS) task with the presentation of the comparison stimuli occurring simultaneously versus successively. Results from previous research lead to the hypothesis that a MTS task with the simultaneous presentation of the comparison stimuli or the successive presentation of the comparison stimuli, will result in acquisition of the MTS task. Further, research also leads to the hypothesis that the acquisition speed will be faster when the comparison stimuli are presented simultaneously than when they are presented successively.
METHODOLOGY Subjects Four White Carneaux pigeons were used in this experiment. All four pigeons had previous operant chamber experience. They were maintained at 80% of their free-feeding body weight. The pigeons were housed in individual home cages where water was continuously available. They obtained food during experimental sessions. The experiment was conducted seven days a week. The birds deprivation level was typically 24 hours, but occasionally varied from 16 hours to 48 hours. Apparatus/Stimuli Two BRS/LVE operant chambers, with three keys, automated food hoppers, and houselights were used. The three keys were horizontally arranged above the food hopper and each key was 2.5 centimeters in diameter. The keys were each separated by 6 centimeters and were 25 centimeters from the floor of the chamber. The floor of the chamber, where the participants stood during training, was covered with brown paper. The food hoppers were located directly below the center response key. Fans were attached to each operant chamber for ventilation. The windows on each chamber door were covered with brown paper, to limit outside light and distractions. The response keys were illuminated from behind by projectors. An IBM compatible computer with MED-PC interface and software program was used to arrange the presentation of stimuli and record the responses made by the pigeons. Food pellets were presented for correct responses. Stimuli were five colors (white, brown, aqua, rose, purple) presented on the response keys. 19
Condition 20 Experimental Design A single-subject, alternating treatments design was utilized. Sessions occurred once per day, seven days per week. Initially, all birds were trained to respond to each of the illuminated keys within the operant chamber. Following preliminary training, the subjects were required to complete a matching-to-sample color identification task in one of two experimental conditions. Each day the subjects were switched to the alternate experimental condition. Throughout the experiment, each color stimulus was presented in random order for equal presentations during each session. Four color combinations were utilized (See Table 1). The color combinations were counterbalanced across subjects, across the conditions, and across the operant chamber boxes. Data were collected to determine when the mastery criterion was met in each experimental condition. Table 1 Color selection Box # 1 3 Bird # 75 61 99 74 Simultaneous Purple, Brown Rose, Brown Rose, Aqua Purple, Aqua Successive Rose, Aqua Purple, Aqua Purple, Brown Rose, Brown Procedure Preliminary Training Each subject was given preliminary training to peck illuminated keys, using each of the five colors (purple, rose, aqua, brown, white), used within the experimental procedure. Approximately equal numbers of reinforcers were provided
21 for the left, center, and right keys, across each of the five colors. The subjects continued training until they successfully pecked the illuminated keys. A progressive ratio schedule of reinforcement was used. The subjects began on a fixed ratio 1 schedule and were progressively increased to a fixed ratio 8 schedule of reinforcement after every 5 reinforcements. Subjects received a maximum of 40 reinforcers in a session. Experimental sessions began on day 5. Matching Procedure The subjects were required to complete a matching-to-sample color identification task. Each subject was given the opportunity to obtain 60 reinforcers per session. If the subject failed to earn 60 reinforcers within a session then the session ceased at 60 minutes. The sequence of presentation of each of the sample and comparison stimuli was randomized each day, such that each color stimulus appeared equally on each of the response keys. On the first day of experimental sessions, Bird 75 and Bird 74 were placed in the simultaneous presentation condition and Bird 99 and Bird 61 were placed in the successive presentation condition. All correct matches were reinforced. Simultaneous matching condition. The sample stimulus was presented on the center key. Five responses to the sample stimulus resulted in the presentation of two comparison stimuli, one on each of the side keys. The sample stimulus remained visible. One of the comparison stimuli was the same color as the sample stimulus and the other comparison stimulus was the alternate color. If the subject did not respond
22 to the sample stimulus within 60 seconds of presentation, then the sample stimulus was darkened, and a 10 second intertrial interval began. A response to the comparison stimulus that matched the sample stimulus resulted in all the keys being darkened and 3-seconds of food being presented. Once the 3-second access to food had ceased, the keys remained dark with the house light on for a 10 second intertrial interval. A response to the comparison stimulus that did not match the sample stimulus (incorrect response) resulted in all the keys being darkened and the house light being turned off (blackout) for 3 seconds. Once the 3-second blackout had ceased, the keys remained dark with the house light on for a 10 second intertrial interval. If a response to either of the comparison stimuli did not occur within 60 seconds of presentation, this was considered an error, the keys were darkened, an intertrial interval occurred, followed by a new trial. While the sample and comparison stimuli were illuminated, any more than 2 responses to the sample stimulus (center key) were considered an incorrect response. Responses made during the blackout had no effect and were not recorded. Pecking non-illuminated keys during the intertrial interval restarted the intertrial interval. Pecking non-illuminated keys during the trial had no effect. Successive matching. The sample stimulus was presented on the center key. Five responses to the sample stimulus resulted in the presentation of one comparison stimulus on one of the side keys and a changeover stimulus (white stimulus) on the other side key. The sample stimulus remained visible. The location of the
23 comparison stimulus and the changeover stimulus was varied on each trial. The comparison stimulus presented was either the same color as the sample stimulus or it was the alternate color. The changeover stimulus remained visible when either matching or non-matching comparison stimuli were presented. A response to the comparison stimulus, when it matched the sample stimulus, resulted in all the keys being darkened and 3-seconds of food being presented. Once the 3-second access to food had ceased, the keys remained dark with the house light on for a 10 second intertrial interval. A response to the comparison stimulus, when it did not match the sample stimulus, resulted in all the keys being darkened and the house light being turned off (blackout) for 3 seconds. Once the 3-second blackout had ceased, the keys remained dark with the house light on for a 10 second intertrial interval. A response to the changeover stimulus, when the comparison stimulus that was presented did not match the sample stimulus, resulted in the comparison stimulus changing to match the sample stimulus. If the subject then responded to the matching comparison stimulus, then the keys were darkened, and food was presented for 3- seconds. Once the 3-second access to food had ended, the keys remained dark with the house light on for a 10 second intertrial interval. If the subject responded to the changeover stimulus a second time (an error), then the keys went dark with the house light off (blackout) for 3 seconds. Once the 3-second blackout had ceased, the keys remained dark with the house light on for a 10 second intertrial interval.
24 A response to the changeover stimulus, when the comparison stimulus that was presented matched the sample stimulus, was considered an error, and resulted in all the keys being darkened with the house light off (blackout) for 3 seconds. Once the 3-second blackout had ceased, the keys remained dark with the house light on for a 10 second intertrial interval. While the sample and comparison stimuli were illuminated, any more than 2 responses to the sample stimulus (center key) were considered an error. Responses made during the blackout had no effect and were not recorded. Pecking nonilluminated keys while the sample stimulus was presented had no effect. Pecking non-illuminated keys during the intertrial interval restarted the intertrial interval. Dependent Variables The percentage of correct responses was calculated for each bird, for each session, in both conditions. The number of trials to reach the criterion minimum of 80% correct responses, for 2 consecutive sessions, was calculated for each bird, for each condition.
RESULTS Bird 99, 75, 74, and 61 completed the current study. Bird 99 reached criterion in both conditions. Bird 75 reached criterion in the simultaneous condition, then reached criterion in the successive condition once the simultaneous condition sessions were discontinued. Birds 74 and 61 reached criterion in the simultaneous condition, but not in the successive condition, even once the simultaneous condition sessions were discontinued. Preliminary Training During preliminary training, all birds were successful in obtaining above 80% of the reinforcements by the fourth session. The following day the matching sessions began. Birds 75 and 74 began in the simultaneous matching condition. Birds 99 and 61 began in the successive matching condition. Matching Procedures The matching procedures were completed during a period of 37 consecutive days. Sessions for all birds did not occur on days 26, 28, and 35. A session was not completed for Bird 75 on day 27. Bird 99 sessions ended after 25 sessions. Bird 75 sessions ended after 31 sessions. Bird 74 sessions ended after 34 sessions. Bird 61 sessions ended after 31 sessions. Bird 61 was placed in box #1, which encountered a machine error (stopped running the program prior to 60 reinforcements/60 minutes) during days 11, 12, 15, 16, 25, 27, and 32. The program also encountered a machine error (would not load the program) on days 20, 33, and 34. Table 2 shows the total number of trials to criterion for all subjects in each condition. 25
Condition 26 Table 2 Trials to Criterion Box # 1 3 Bird # 75 61 99 74 Simultaneous 420 971 544 674 Successive 1185 948+ 828 2003+ + indicates mastery criterion was not reached *Note: equipment failure prevented continuation of the successive condition for Bird 61 Bird 99 reached the minimum mastery criterion of 80% across 2 consecutive sessions in the simultaneous condition prior to the successive condition (figure 1). Alternating condition sessions were continued until Bird 99 reached the minimum mastery criterion in the successive condition. Bird 99 reached the minimum mastery criterion after 544 trials in the simultaneous condition and 828 trials in the successive condition (figure 2).
# Trials Percent of Trials Correctly Matched 27 Figure 1 Bird #99 Percentage of Correct Trials by Color and Condition 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Session # SIM Rose SIM Aqua SUC Purple SUC Brown Figure 2 1000 Bird #99 Cumulative Trials to Criterion 800 600 400 SIM SUC 200 0 0 5 10 15 20 Session #
Percent of Trials Correctly Matched 28 Bird 75 reached the minimum mastery criterion in the simultaneous condition prior to the successive condition (figure 3). Simultaneous condition sessions were ended after the 15 th session, to increase the likelihood that Bird 75 would achieve mastery in the successive condition. Bird 75 reached the minimum mastery criterion after 420 trials in the simultaneous condition, and met the mastery criterion in the successive condition, once the simultaneous sessions were discontinued, after 1185 trials (figure 4). Figure 3 Bird #75 Percentage of Correct Trials by Color and Condition 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 Session # SIM Purple SIM Brown SUC Rose SUC Aqua
# Trials 29 Figure 4 Bird #75 Cumulative Trials to Criterion 1400 1200 1000 800 600 400 SIM SUC 200 0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 Session # Bird 74 reached the minimum mastery criterion in the simultaneous condition prior to the successive condition (figure 5). Simultaneous condition sessions were terminated after the 14 th session, to increase the likelihood that Bird 74 would achieve mastery of the successive condition. Bird 74 reached the minimum mastery criterion after 674 trials in the simultaneous condition and failed to reach the minimum mastery criterion in the successive condition after 2003 trials (figure 6).
# Trials Percent of TrialsCorrectly Matched 30 Figure 5 Bird #74 Percentage of Correct Trials by Color and Condition 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 Session # SIM Purple SIM Aqua SUC Rose SUC Brown Figure 6 2200 2000 1800 1600 1400 1200 1000 800 600 400 200 0 Bird #74 Cumulative Trials to Criterion 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 Session # SIM SUC
Percent of Trials Correctly Matched 31 Bird 61 reached the mastery criterion in the simultaneous condition prior to the successive condition (figure 8). Bird 61 reached the mastery criterion in the simultaneous condition after 971 trials, and failed to achieve the mastery criterion in the successive condition after 948 trials (figure 4). Figure 7 Bird #61 Percentage of Correct Trials by Color and Condition 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 Session # SIM Rose SIM Brown SUC Purple SUC Aqua
# Trials 32 Figure 8 Bird #61 Cumulative Trials to Criterion 1200 1000 800 600 400 SIM SUC 200 0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 Session # *Note: Open circles and triangles indicate days of program malfunctions
DISCUSSION The hypothesis that the subjects would master the matching-to-sample task in both conditions is partially confirmed. Two subjects mastered the matching-tosample task in both the simultaneous presentation and the successive presentation conditions. Two subjects mastered the matching-to-sample task in the simultaneous presentation condition, but failed to master the matching-to-sample task in the successive condition. However, the data indicate that continued sessions of the successive condition may have eventually produced mastery of the task by all four subjects. The hypothesis that subjects would master the matching-to-sample task in the simultaneous condition faster than in the successive condition is confirmed. Three of the four subjects achieved mastery in the simultaneous condition in significantly fewer trials than in the successive condition. One subject achieved mastery of the simultaneous condition at 971 trials, and did not reach criterion in the successive condition after 948 trials. After 948 trials the subject had achieved 85% success for one color and 63% success with the other. If the trend continued, mastery of the successive condition would have required at least two additional sessions. The findings are consistent with previous research with human subjects on the acquisition of a matching-to-sample task utilizing simultaneous and successive presentation methods of the comparison stimuli (Baker & Lawrence, 1951; Berryman et al., 1963; Bodily, Katz, & Wright, 2008; Butter & Snyder, 1982; Cumming et al., 1965; Grice, 1948; Jeffrey, 1961; Lipsitt, 1961; Loess & Duncan, 1952; Samuels, 33