Paula Magalhães

Suboptimal choice in nonhuman animals: Rats commit the sunk cost error

The present experiments investigated the sunk cost error, an apparently irrational tendency to persist with an initial investment, in rats. This issue is of interest because some have argued that nonhuman animals do not commit this error. Two or three fixed-ratio (FR) response requirements were arranged on one lever, and an escape option was arranged on a second lever. The FRs were of different sizes, and escaping was the behavior of interest. Several variables that might influence the decision to persist versus escape were manipulated: the number of trials with different FR schedules in an experimental session (Exps. 1 and 2), effort to escape (Exp. 2), and the size of the larger FR (Exp. 3). The sunk cost error would result in never escaping, and the optimal strategy would be to escape from the larger FR. The main variable that determined persisting versus escaping was the size of the large FR. Rats that escaped from the large FR—apparently optimal behavior—did so at a suboptimal point, and hence committed the sunk cost error.

Sunk cost and work ethic effects reflect suboptimal choice between different work requirements.

We investigated suboptimal choice between different work requirements in pigeons (Columba livia), namely the sunk cost effect, an irrational tendency to persist with an initial investment, despite the availability of a better option. Pigeons chose between two keys, one with a fixed work requirement to food of 20 pecks (left key), and the other with a work requirement to food which varied across conditions (center key). On some trials within each session, such choices were preceded by an investment of 35 pecks on the center key, whereas on others they were not. On choice trials preceded by the investment, the pigeons tended to stay and complete the schedule associated with the center key, even when the number of pecks to obtain reward was greater than for the concurrently available left key. This result indicates that pigeons, like humans, commit the sunk cost effect. With higher work requirements, this preference was extended to trials where there was no initial investment, so an overall preference for the key associated with more work was evident, consistent with the work ethic effect. We conclude that a more general work ethic effect is amplified by the effect of the prior investment, that is, the sunk cost effect.

The effects of food presentation at regular or irregular times on the development of activity-based anorexia in rats

Activity-based anorexia occurs when food availability is restricted to 1h of the day and a wheel is freely available to the rest of the time. Under such conditions rats run excessively and stop eating even during periods in which food is available. A defining characteristic of the excessive activity is that there is a peak of running in the anticipation of food availability. The present study was designed to test whether the occurrence of the food period at different times of the light phase of the light-dark cycle (from 08:00 to 20:00h) could impede or postpone the normal development of activity anorexia. We compared the effect of presenting the food at a fixed time of the light period with presenting it on a variable schedule. Far from impeding or postponing the development of activity-based anorexia, presenting food at irregular times resulted in a pronounced body-weight loss, a low food intake and an increase in locomotor activity. Animals ran excessively, with a peak at the start of the dark period, and again when lights were turned on in the experimental room (running in the anticipation of food). Both fixed and variable schedules of food availability resulted in the development of activity-based anorexia in rats.

The sunk cost effect across species: A review of persistence in a course of action due to prior investment.

The sunk cost effect is the bias or tendency to persist in a course of action due to prior investments of effort, money or time. At the time of the only review on the sunk cost effect across species (Arkes & Ayton, 1999), research with nonhuman animals had been ecological in its nature, and the findings about the effect of past investments on current choice were inconclusive. However, in the last decade a new line of experimental laboratory-based research has emerged with the promise of revolutionizing the way we approach the study of the sunk cost effect in nonhumans. In the present review we challenge Arkes and Aytons conclusion that the sunk cost effect is exclusive to humans, and describe evidence for the sunk cost effect in nonhuman animals. By doing so, we also challenge the current explanations for the sunk cost effect in humans, as they are not applicable to nonhumans. We argue that a unified theory is called for, because different independent variables, in particular, investment amount, have the same influence on the sunk cost effect across species. Finally, we suggest possible psychological mechanisms shared across different species, contrast and depreciation, that could explain the sunk cost effect.

The effect of a prior investment on choice: the sunk cost effect.

We investigated the effect of prior investment on choice in pigeons, namely, the sunk cost effect, which is a tendency to continue an endeavor once a prior investment has been made, despite a better option being available. In a concurrent-chains procedure, pigeons chose between left and right keys in the choice phase leading to different work requirements in the outcome phase. Within each session, two components were signaled by red or green keys in the choice phase. Components were identical, except that in red components, the choice was preceded by a prior investment of 20 pecks on the left key, whereas in green components, the investment of 20 pecks was on the right key. Preference for the key with the prior investment was studied in a series of experiments in which we manipulated the absence or presence of the investment (Experiments 1a and 1b) and size of the investment (Experiments 2 and 3). We also investigated whether the bias observed was a result of carryover effects or of the sunk cost effect (Experiment 4). Overall, the results showed that choice was biased toward the alternative associated with the prior investment, consistent with the sunk cost effect, an effect that can be understood in terms of within-trial contrast and the delay-reduction hypothesis.

A good time to leave?: the sunk time effect in pigeons

Persistence in a losing course of action due to prior investments of time, known as the sunk time effect, has seldom been studied in nonhuman animals. On every trial in the present study, pigeons were required to choose between two response keys. Responses on one key produced food after a short fixed interval (FI) of time on some trials, or on other trials, no food (Extinction) after a longer time. FI and Extinction trials were not differently signaled, were equiprobable, and alternated randomly. Responses on a second Escape key allowed the pigeon to terminate the current trial and start a new one. The optimal behavior was for pigeons to peck the escape key once the duration equivalent to the short FI had elapsed without reward. Durations of the short FI and the longer Extinction schedules were varied over conditions. In some conditions, the pigeons suboptimally responded through the Extinction interval, thus committing the sunk time effect. The absolute duration of the short FI had no effect on the choice between persisting and escaping. Instead, the ratio of FI and Extinction durations determined the likelihood of persistence during extinction.

The sunk cost effect in pigeons and people: A case of within-trials contrast?

Pigeons show the sunk cost effect in procedures in which their choice between two outcomes is biased by a prior investment. We review recent studies of the sunk cost effect in pigeons, in which choice procedures are analogous to studies with humans using hypothetical scenarios to make explicit a prior investment and the later choice. Zentalls (2010) theory of within-trial contrast can account for the sunk cost effect - an effortful prior investment contrasts with choice outcomes to increase the value of the outcome in which the prior investment was made. The account correctly predicts that in both pigeons and humans, increased prior investment increases the sunk cost effect. We present data from a study with humans using hypothetical scenarios in which delay was varied between the time of the prior investment and later choice. Extending the delay reduced the sunk cost effect, suggesting the need for a second process by which value is depreciated, in addition to the value-enhancing effect of contrast. This article is part of a Special Issue entitled: Tribute to Tom Zentall.

Games used with serious purposes: a systematic review of interventions in patients with cerebral palsy

The purpose of the present systematic review was to examine extant research regarding the role of games used seriously in interventions with individuals with cerebral palsy. Therefore, PubMed, PsyINFO, Web of Science, Scopus, and IEEE databases were used. Search terms included: “serious games” OR “online games” OR “video games” OR “videogame” OR “game based” OR “game” AND “intervention” AND “cerebral palsy.” After the full reading and quality assessment of the papers, 16 studies met the inclusion criteria. The majority of the studies reported high levels of compliance, motivation, and engagement with game-based interventions both at home and at the clinical setting intervention. Regarding the effectiveness of the use of games, the results of the studies show both positive and negative results regarding their effectiveness. The efficacy was reported to motor function (i.e., improvements in the arm function, hand coordination, functional mobility, balance and gait function, postural control, upper-limbs function) and physical activity. Findings of this review suggest that games are used as a complement to conventional therapies and not as a substitute. Practitioners often struggle to get their patients to complete the assigned homework tasks, as patients display low motivation to engage in prescribed exercises. Data of this review indicates the use of games as tools suited to promote patients’ engagement in the therapy and potentiate therapeutic gains.

How Executive Functions Are Evaluated in Children and Adolescents with Cerebral Palsy? A Systematic Review

Aims: The aim of the present study was to examine how executive functions are assessed in children and adolescents with Cerebral Palsy. Method: A systematic literature review was conducted using four bibliographic databases (WebScience, Scopus, PubMed, and Psycinfo), and only studies that evaluated at least one executive function were selected. Both the research and reporting of results were based on Cochranes recommendations and PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines. Results: The instrument most frequently used was the D-KEFS. All studies point to the existence of impairments in the executive functions among children and adolescents with Cerebral Palsy with an impact on several cognitive and life domains. Interpretation: There is a need to further systematize the research protocols to study the executive functions and their assessment in the intervention context. Findings of this review presented a diversity of tests (e.g., D-KEFS) or tasks (e.g., The inhibitory ability task) used with children with Cerebral Palsy. However, no information was given about adaptations performed to the test/task to meet Cerebral Palsys specificities. Future research could consider including this information, which is key both to researchers and practitioners. The results of this study have important implications and suggestions for future avenues and guidelines for research and practice.

“My Child has Cerebral Palsy”: Parental Involvement and Children’s School Engagement

Engaged students tend to show school-committed behaviors (e.g., attend classes, get involved with the learning process), high achievement, and sense of belonging. However, students with disabilities are prone to show a lack of engagement with school due to the specific difficulties they have to handle. In fact, children with disabilities are likely to show poor participation in school when compared with children without disabilities. This poor involvement is related to their low autonomy to participate in the school activities, which, in turn, results in low school engagement. Parents play a crucial role in their children’s education. Parental involvement in school activities promotes autonomous behaviors and, consequently, school engagement. In fact, extant literature has shown close relationships between parental involvement, school engagement, and academic performance. Yet, parental involvement in school activities of children with Cerebral Palsy (CP) has received little direct attention from researchers. These children tend to display lower participation due to the motor, or cognitive, impairments that compromise their autonomy, and have a high likelihood to develop learning disabilities, with special incidences in reading and arithmetic. Therefore, our aim is twofold, to understand the parental styles; and how the perceived parental involvement in school activities is related to their children school engagement. Hence, 19 interviews were conducted with one of the parents of 19 children with CP. These interviews explored the school routines of children and the perceived involvement of parents in those routines. Additionally, children filled out a questionnaire on school engagement. Results show that the majority of the parents were clustered in the Autonomy Allowance and Acceptance and Support parental style, and the majority of their children were perceived as autonomous. Moreover, about a half of the children reported a high level of school engagement. Finally, neither children’s autonomous behaviors reported by parents, nor parental style, seem to be related with the children’s level of school engagement. Rehabilitation centers and schools could consider training parents/caregivers focusing on their educational needs, promotion of reflections on the usefulness of applying autonomy promotion strategies with their child, and foster their involvement.