Response-rate differences in variable-interval and variable-ratio schedules: An old problem revisited

In Experiment 1, a variable-ratio 10 schedule became, successively, a variable-interval schedule with only the minimum interreinforcement intervals yoked to the variable ratio, or a variable-interval schedule with both interreinforcement intervals and reinforced interresponse times yoked to the variable ratio. Response rates in the variable-interval schedule with both interreinforcement interval and reinforced interresponse time yoking fell between the higher rates maintained by the variable-ratio schedule and the lower rates maintained by the variable-interval schedule with only interreinforcement interval yoking. In Experiment 2, a tandem variable-interval 15-s variable-ratio 5 schedule became a yoked tandem variable-ratio 5 variable-interval x-s schedule, and a tandem variable-interval 30-s variable-ratio 10 schedule became a yoked tandem variable-ratio 10 variable-interval x-s schedule. In the yoked tandem schedules, the minimum interreinforcement intervals in the variable-interval components were those that equated overall interreinforcement times in the two phases. Response rates did not decline in the yoked schedules even when the reinforced interresponse times became longer. Experiment 1 suggests that both reinforced interresponse times and response rate–reinforcement rate correlations determine response-rate differences in variable-ratio 10 and yoked variable-interval schedules in rats. Experiment 2 suggests a minimal role for the reinforced interresponse time in determining response rates on tandem variable-interval 30-s variable-ratio 10 and yoked tandem variable-ratio 10 variable-interval x-s schedules in rats.     

Operant hoarding: a new paradigm for the study of self-control.

In the first of four experiments, rats were exposed to a modified multiple continuous reinforcement-extinction schedule during 15-min daily sessions. In one condition (saves condition) with the cuelight on, a single lever press produced a food pellet, briefly extinguished the cuelight, and started a clock. Saves (additional lever presses with interresponse times less than 1 s) produced an additional food pellet, briefly extinguished the cuelight, and restarted the interresponse time clock. The cuelight was extinguished 1 s after the last lever press and remained off during a 10-s period of extinction, during which no food pellets were delivered. In the other condition (savings account condition), the contingencies were the same except that the cuelight was extinguished and was not reilluminated after the initial lever press, and the delivery of all food pellets in the reinforcement component was delayed until the onset of extinction. In both conditions, rats made saves, but mean saves (total saves divided by the number of reinforcement components) were slightly reduced in the savings account condition. In Experiment 2, using six equally spaced 15-min sessions per day on alternate days, saves were either followed immediately with food and brief cuelight offset (saves condition) or were not reinforced at all. Mean saves were much greater when saves were reinforced. In Experiment 3, during 5-min daily sessions, saves earned a single pellet (savings account condition) or a number of pellets equal to the ordinal number of the lever press (interest condition). Rats made fewer mean saves, with little change in the food rate, when saves earned interest. In Experiment 4, the rats earned all their food in the operant situation during 24 daily 5-min sessions, these separated by 55-min intersession intervals during which no food was available; otherwise, the conditions were the same as in Experiment 3. In Experiment 4, the shift to interest for saves led to an increase in mean daily mean saves (total daily mean saves divided by the number of daily sessions) as well as to an increase in the number of food pellets delivered in each session. The results are discussed in terms of self-control and behavioral economics.     

Functionalism and inverted spectra

Functionalism, a philosophical theory, has empirical consequences. Functionalism predicts that where systematic transformations of sensory input occur and are followed by behavioral accommodation in which normal function of the organism is restored such that the causes and effects of the subject's psychological states return to those of the period prior to the transformation, there will be a return of qualia or subjective experiences to those present prior to the transform. A transformation of this type that has long been of philosophical interest is the possibility of an inverted spectrum. Hilary Putnam argues that the physical possibilty of acquired spectrum inversion refutes functionalism. I argue, however, that in the absence of empirical results no a priori arguments against functionalism, such as Putnam's, can be cogent. I sketch an experimental situation which would produce acquired spectrum inversion. The mere existence of qualia inversion would constitute no refutation of functionalism; only its persistence after behavioral accommodation to the inversion would properly count against functionalism. The cumulative empirical evidence from experiments on image inversion suggests that the results of actual spectrum inversion would confirm rather than refute functionalism.     

Grasp force control in older adults

Diminished tactile sensibility and impaired hand dexterity have been reported for elderly individuals. Reports that younger adults with severely impaired tactile sensibility use excessive grasp force during routine grasp and manipulation tasks raise the possibility that elderly persons likewise produce large grasp forces that may contribute to impaired dexterity. Impaired pseudomotor functioning also occurs in elderly subjects and may yield a slipperier skin surface that enhances the possibility for excessive grasp force. The present study measured grasp force in 10 elderly and 9 young adult individuals, during grasp and vertical lift of a small object, using a precision (pinch) grip of the thumb and index finger. The slipperiness of the object's gripped surfaces was unexpectedly varied. Skin slipperiness was estimated by also measuring the grasp force at which the object slipped from grasp. The older subjects employed grasp forces that were, on average, twice as large as those of the young subjects, with some producing forces many times greater than the young subjects' average grip force. Grip forces also were significantly more variable across trials in older subjects. This increased variability was not caused simply by the elderly subjects' increased grip force. A portion of the increased force was due to increased skin slipperiness. The grip force that the elderly subjects produced in excess of the slip force (the "margin of safety" against object slippage) was larger than would have been predicted from their skin slipperiness, however. It is suggested that, in part, the excessive grasp forces represent a strategic response to tactile sensibility impairment. Twopoint discrimination limina in the older subjects averaged about four times greater than in the younger subjects. Increased grasp forces in elderly persons may result from other factors, such as increased variability in grip force production. The contributions of excessive grasp forces to impaired dexterity in older persons still need to be addressed experimentally.     

Artificial intelligence and personal identity

Considerations of personal identity bear on John Searle's Chinese Room argument, and on the opposed position that a computer itself could really understand a natural language. In this paper I develop the notion of a virtual person, modelled on the concept of virtual machines familiar in computer science. I show how Searle's argument, and J. Maloney's attempt to defend it, fail. I conclude that Searle is correct in holding that no digital machine could understand language, but wrong in holding that artificial minds are impossible: minds and persons are not the same as the machines, biological or electronic, that realize them.     

Goal disruption during COVID-19: Reimagining goals during a global pandemic

The COVID-19 pandemic has been a major source of professional and personal disruption and has had both direct and downstream consequences on almost every aspect of peoples' lives, including their personal goal pursuits. In the face of unexpected hardships and obstacles, people have had to find new paths to goal achievement. In the present work, we examined whether difficulty adjusting goal pursuit during the global disruption of the COVID-19 pandemic is related to negative affective, cognitive, and behavioral goal-related outcomes. Across two studies, we found that people who had more difficulty adjusting their goal pursuit during the pandemic experienced more negative feelings toward their goals, were less satisfied with the status of their goals, and were less likely to actually achieve their goals. Moreover, individual differences in planning tendencies, need for predictability, general adaptability, and perceived pandemic disruption were related to more difficulty adjusting goal pursuit. This work demonstrates the importance of flexibility in the face of setbacks and obstacles, especially during times of disruption and uncertainty.     

Stages of Learning Motivation: Development and Validation of a Measure1

Prochaska and colleagues’(e.g., Prochaska, DiClemente, & Norcross, 1992) stages‐of‐change theory was employed in the current study to reconceptualize the assessment of motivation to learn. We used the stages‐of‐change framework to develop and test a multidimensional measure of learning motivation using 3 independent samples. The pattern of relationships among the learning stages and learning criteria provided strong support for the appropriateness of using a stage‐based perspective to frame learning motivation. In addition, hierarchical regression analysis showed that the Stages of Learning Motivation Inventory (SOLMI) explained variance in the criteria (e.g., exam average, class satisfaction) beyond controls and a commonly used measure of learning motivation. Implications for practice and future research are discussed.     

Non‐zero‐sum collaboration,reciprocity, and the preference for similarity: Developing an adaptive model of close relational functioning

An evolutionary framework was used to develop a model of relational functioning among friends. The proposed model focuses on the collaborative nature of close friendships and attempts to highlight two adaptive mechanisms important in creating non‐zero‐sum outcomes among highly interdependent parties. The model emphasizes the importance of reciprocity in creating mutually beneficial outcomes through social exchange, and it articulates how the preference for similarity is useful when creating non‐zero‐sum rewards through synergistic coordination. In particular, the focus is on the unique role that shared interests and mutual knowledge play when individuals attempt to pursue common goals through joint activity. The implications of the model are discussed with respect to a host of issues ranging from deceptive communication to relational satisfaction and commitment.     

Rapid automatized naming (RAN) in children with ADHD: An ex-Gaussian analysis

Children with ADHD demonstrate increased frequent “lapses” in performance on tasks in which the stimulus presentation rate is externally controlled, leading to increased variability in response times. It is less clear whether these lapses are also evident during performance on self-paced tasks, e.g., rapid automatized naming (RAN), or whether RAN inter-item pause time variability uniquely predicts reading performance. A total of 80 children aged 9 to 14 years—45 children with attention-deficit/hyperactivity disorder (ADHD) and 35 typically developing (TD) children—completed RAN and reading fluency measures. RAN responses were digitally recorded for analyses. Inter-stimulus pause time distributions (excluding between-row pauses) were analyzed using traditional (mean, standard deviation [SD], coefficient of variation [CV]) and ex-Gaussian (mu, sigma, tau) methods. Children with ADHD were found to be significantly slower than TD children (p < .05) on RAN letter naming mean response time as well as on oral and silent reading fluency. RAN response time distributions were also significantly more variable (SD, tau) in children with ADHD. Hierarchical regression revealed that the exponential component (tau) of the letter-naming response time distribution uniquely predicted reading fluency in children with ADHD (p < .001, ΔR² = .16), even after controlling for IQ, basic reading, ADHD symptom severity and age. The findings suggest that children with ADHD (without word-level reading difficulties) manifest slowed performance on tasks of reading fluency; however, this “slowing” may be due in part to lapses from ongoing performance that can be assessed directly using ex-Gaussian methods that capture excessively long response times.