Marco Vasconcelos - Academia.edu (original) (raw)

Papers by Marco Vasconcelos

Behavioural Processes, 2006

To test some predictions of scalar expectancy theory (SET) for the time-left procedure, we perfor... more To test some predictions of scalar expectancy theory (SET) for the time-left procedure, we performed one experiment with two conditions. In Condition A, pigeons were exposed to two fixed-interval schedules, a fixed-interval (FI) 30 s and an FI 60 s, each associated with a distinct key and presented on a separate trial. Subsequently, during test trials, the FI 60-s key was illuminated and then after T = 15, 30 or 45 s the FI 30-s key also was illuminated. The main issue was how choice between the two keys varied with T. Condition B replicated Condition A with different FI parameters and T values. The results showed that (a) contrary to SET's predictions, preference changed reliably with testing, which suggests that learning took place during the test trials; (b) within each test trial, pigeons revealed an almost exclusive preference for one of the keys, and (c) at steady state pigeons behaved in the same way as rats. Because SET could not account for these findings we advanced a new descriptive model of performance for the time-left task. The model fit the data well.

Journal of Experimental Psychology: Animal Learning and Cognition, 2016

Behavioural Processes, 2008

Frontiers in psychology, 2015

Animal cognition, Jan 21, 2016

Inspired by Spence's seminal work on transposition, we propose a synthetic approach to unders... more Inspired by Spence's seminal work on transposition, we propose a synthetic approach to understanding the temporal control of operant behavior. The approach takes as primitives the temporal generalization gradients obtained in prototypical concurrent and retrospective timing tasks and then combines them to synthetize more complex temporal performances. The approach is instantiated by the learning-to-time (LeT) model. The article is divided into three parts. In the first part, we review the basic findings concerning the generalization gradients observed in fixed-interval schedules, the peak procedure, and the temporal generalization procedure and then describe how LeT explains them. In the second part, we use LeT to derive by gradient combination the typical performances observed in mixed fixed-interval schedules, the free-operant psychophysical procedure, the temporal bisection task, and the double temporal bisection task. We also show how the model plays the role of a useful nul...

Quarterly journal of experimental psychology (2006), Jan 25, 2015

We investigated the effects of interdimensional discrimination training in the temporal generaliz... more We investigated the effects of interdimensional discrimination training in the temporal generalization gradient. In a matching-to-sample task, pigeons learned to choose key S after a T-s houselight sample and key NS in the absence of the houselight sample. For one group of pigeons, T = 20 s; for another, T = 10 s. Subsequently, houselight duration was varied to obtain temporal generalization gradients. Results showed that (a) proportion S increased as houselight duration ranged from 0 s to T s and then remained high for houselight durations longer than T; (b) the gradients were well described by negative-exponential functions; (c) these non-flat gradients were present from the beginning of testing, and; (d) the average gradients obtained with T = 20 s and T = 10 s overlapped when plotted in relative time. We conclude that temporal control does not require explicit discrimination training along the temporal dimension, and that temporal generalization gradients obtained with an interd...

Symmetry (the ability to match B to A after learning to match A to B) has been difficult to obser... more Symmetry (the ability to match B to A after learning to match A to B) has been difficult to observe in nonhumans. This difficulty led to the appreciation that a stimulus to us is quite different from the functional stimulus for other animals. Animals seem to perceive stimuli as a conjunction of visual, spatial, and temporal characteristics and when such

Scientific Reports, 2015

because subjects do not actively choose a lower reward probability. Analogous findings have also ... more because subjects do not actively choose a lower reward probability. Analogous findings have also been reported in the fields of economics and neuroscience . Yet, similarly to the typical Z-protocol results, there is evidence that under some circumstances monkeys will reliably sacrifice amount of reward to obtain advanced information about the outcome of their choices 20 .

PsycEXTRA Dataset, 2000

Biology Letters, 2012

Empathy, the capacity to recognize and share feelings experienced by another individual, is an im... more Empathy, the capacity to recognize and share feelings experienced by another individual, is an important trait in humans, but is not the same as pro-sociality, the tendency to behave so as to benefit another individual. Given the importance of understanding empathy's evolutionary emergence, it is unsurprising that many studies attempt to find evidence for it in other species. To address the question of what should constitute evidence for empathy, we offer a critical comparison of two recent studies of rescuing behaviour that report similar phenomena but are interpreted very differently by their authors. In one of the studies, rescue behaviour in rats was interpreted as providing evidence for empathy, whereas in the other, rescue behaviour in ants was interpreted without reference to sharing of emotions. Evidence for empathy requires showing that actor individuals possess a representation of the receiver's emotional state and are driven by the psychological goal of improving its wellbeing. Proving psychological goal-directedness by current standards involves goal-devaluation and causal sensitivity protocols, which, in our view, have not been implemented in available publications. Empathy has profound significance not only for cognitive and behavioural sciences but also for philosophy and ethics and, in our view, remains unproven outside humans.

Behavioural processes, Jan 1, 2006

We report six unsuccessful attempts to replicate the ''work ethic'' phenomenon reported by . In E... more We report six unsuccessful attempts to replicate the ''work ethic'' phenomenon reported by . In Experiments 1-5, pigeons learned two simultaneous discriminations in which the S+ and S2 stimuli were obtained by pecking an initial stimulus once or multiple (20 or 40) times. Subsequent preference tests between the S+ stimuli and between the S2 stimuli mostly revealed indifference, on average, between the S+ from the multiple-peck (high-effort) trials and the S+ from the one-peck (low-effort) trials, and likewise between the two respective S2 stimuli. Using a slightly different procedure that permitted assessment of the relative aversiveness of low versus high effort, Experiment 6 again revealed a pattern of indifference despite showing that pigeons took considerably longer to begin pecking on high-than on low-effort trials. Our findings call into question the reliability of the original findings and the sufficiency of the hypothesized within-trial contrast mechanism to produce them.

Symmetry has been difficult to observe in nonhumans mainly because they seem to perceive stimuli ... more Symmetry has been difficult to observe in nonhumans mainly because they seem to perceive stimuli as a conjunction of visual, spatial, and temporal characteristics. When such characteristics are controlled, symmetry does emerge in nonhumans (cf. Frank and Wasserman, 2005;. Recently, however, reported symmetry in pigeons without controlling for temporal order.

To understand how effort, defined by number of responses required to obtain a reward, affects rew... more To understand how effort, defined by number of responses required to obtain a reward, affects reward value, five pigeons were exposed to a self-control task. They chose between two alternatives, 2 s of access to food after a delay of 10 s, and 6 s of access to food after an adjusting delay. The adjusting delay increased or decreased depending on the pigeons' choices. The delay at which the two alternatives were equally chosen defined the indifference point. To determine whether requiring responses during the delay led to more impulsive (smaller-sooner rewards) or self-controlled (larger-later rewards) choices, we varied the number of required pecks during the 10-s delay to the 2-s reinforcer, and assessed how the requirement affected the indifference points. In the High Rate Phase, they had to peck at least 10 times during the delay; in the Low Rate Phase, they could peck at most 5 times during the delay. For four pigeons the indifference point increased with the response requirement; for one pigeon it decreased. The results suggest that, in general, reward value varies inversely with effort.

Charles Darwin aided his private decision making by an explicit deliberation, famously deciding w... more Charles Darwin aided his private decision making by an explicit deliberation, famously deciding whether or not to marry by creating a list of points in a table with two columns: "Marry" and "Not Marry". One hundred seventy-two years after Darwin's wedding, we reconsider whether this process of choice, under which individuals assign values to their options and compare their relative merits at the time of choosing (the tug-of-war model), applies to our experimental animal, the European Starling, Sturnus vulgaris. We contrast this with the sequential choice model that postulates that decision-makers make no comparison between options at the time of choice. According to the latter, behaviour in simultaneous choices reflects adaptations to contexts with sequential encounters, in which the choice is whether to take an opportunity or let it pass. We postulate that, in sequential encounters, the decision-maker assigns (by learning) a subjective value to each option, reflecting its payoff relative to background opportunities. This value is expressed as latency and/or probability to accept each opportunity as opposed to keep searching. In simultaneous encounters, choice occurs through each option being processed independently, by a race between the mechanisms that generate option-specific latencies. We describe these alternative models and review data supporting the predictions of the sequential choice model.