Study of Intertemporal Discounting According to Age Groups

The paper focuses on the topic of intertemporal discounting of individuals according to age groups. Using the sample of examined individuals, it aims to verify the hypothesis that the patience of individuals decreases with their increasing age. The study included a total of 599 individuals with an average age of 38.3 years (min. 16 and max. 82 years) who answered classical questions focused on time discounting and impulsive behaviour. In total, four possible scenarios were analysed: a small reward (CZK 100) with a delay of 1 day, a small reward with a delay of 1 month, a large reward (CZK 100,000) with a delay of 1 day and a large reward with a delay of 1 month. The delayed reward was always increased by 10% (i.e., CZK 110 or CZK 110,000). The basic hypothesis was that with increasing age, the subjective discount rate increases i.e., patience decreases. The above-mentioned 4 scenarios were evaluated for the hypotheses, while only three of the four scenarios were confirmed for all hypotheses. The results in the examined individuals suggest that with increasing age, there is a decrease in patience and at the same time a decrease in impulsive behaviour. These findings may have an overlap in consumption or savings in relation to the aging population.

The effect of age on discrimination learning and self-control in a marshmallow test for pigs

Both humans and nonhuman animals need to show self-control and wait for a larger or better reward instead of a smaller or less preferred but instant reward on an everyday basis. We investigated whether this ability undergoes ontogenetic development in domestic pigs (similar to what is known in human infants) by testing if and for how long nine- and 16-week-old pigs wait for a larger amount of their preferred reward. In a delay-of-gratification task, animals first learned that a small reward was hidden under a white cup and a large reward under a black cup, and then the delay to deliver the large reward was gradually increased. The results show that older pigs could wait longer for a larger reward than younger pigs (10.6 ± 1.3 s vs. 5.2 ± 1.5 s), thereby confirming our hypothesis of ontogenetic development of self-control in pigs. This self-control is likely to be regulated by the behavioural inhibition system and associated systems. Self-control or, more specifically the lack of it may be involved in the development of abnormal behaviours, not only in humans but also in animals. Therefore, research on self-control in decision-making might provide a new perspective on abnormal behaviours in captive animals.

Competition Rather Than Observation and Cooperation Facilitates Optimal Motor Planning

Humans tend to select motor planning with a high reward and low success compared with motor planning, which has a small reward and high success rate. Previous studies have shown such a risk-seeking property in motor decision tasks. However, it is unclear how to facilitate a shift from risk-seeking to optimal motor planning that maximizes the expected reward. Here, we investigate the effect of interacting with virtual partners/opponents on motor plans since interpersonal interaction has a powerful influence on human perception, action, and cognition. This study compared three types of interactions (competition, cooperation, and observation) and two types of virtual partners/opponents (those engaged in optimal motor planning and those engaged in risk-averse motor planning). As reported in previous studies, the participants took a risky aim point when they performed a motor decision task alone. However, we found that the participant's aim point was significantly modulated when they performed the same task while competing with a risk-averse opponent (p = 0.018) and that there was no significant difference from the optimal aim point (p = 0.63). No significant modulation in the aim points was observed during the cooperation and observation tasks. These results highlight the importance of competition for modulating suboptimal decision-making and optimizing motor performance.

Parametric shift from rational to irrational decisions in mice

In the classical view of economic choices, subjects make rational decisions evaluating the costs and benefits of options in order to maximize their overall income. Nonetheless, subjects often fail to reach optimal outcomes. The overt value of an option drives the direction of decisions, but covert factors such as emotion and sensitivity to sunk cost are thought to drive the observed deviations from optimality. Many questions remain to be answered as to (1) which contexts contribute the most to deviation from an optimal solution; and (2) the extent of these effects. In order to tackle these questions, we devised a decision-making task for mice, in which cost and benefit parameters could be independently and flexibly adjusted and for which a tractable optimal solution was known. Comparing mouse behavior with this optimal solution across parameter settings revealed that the factor most strongly contributing to suboptimal performance was the cost parameter. The quantification of sensitivity to sunk cost, a covert factor implicated in our task design, revealed it as another contributor to reduced optimality. In one condition where the large reward option was particularly unattractive and the small reward cost was low, the sensitivity to sunk cost and the cost-led suboptimality almost vanished. In this regime and this regime only, mice could be viewed as close to rational (here, ‘rational’ refers to a state in which an animal makes decisions basing on objective valuation, not covert factors). Taken together, our results suggest that “rationality” is a task-specific construct even in mice.

Learned valuation during forage decision-making in cuttlefish

Decision-making, when humans and other animals choose between two options, is not always based on the absolute values of the options but can also depend on their relative values. The present study examines whether decision-making by cuttlefish is dependent on relative values learned from previous experience. Cuttlefish preferred a larger quantity when making a choice between one or two shrimps (1 versus 2) during a two-alternative forced choice. However, after cuttlefish were primed under conditions where they were given a small reward for choosing one shrimp in a no shrimp versus one shrimp test (0 versus 1) six times in a row, they chose one shrimp significantly more frequently in the 1 versus 2 test. This reversed preference for a smaller quantity was not due to satiation at the time of decision-making, as cuttlefish fed a small shrimp six times without any choice test prior to the experiment still preferred two shrimps significantly more often in a subsequent 1 versus 2 test. This suggests that the preference of one shrimp in the quantity comparison test occurs via a process of learned valuation. Foraging preference in cuttlefish thus depends on the relative value of previous prey choices.

Not when but if: Modality and future time reference in English, Dutch and German

Recently, economists have used notions of linguistic relativity to suggest that grammatical constraints on Future Time Reference (FTR) affect whether people choose to take a small reward now or wait until later for a larger reward ("temporal discounting"). Economists hypothesize that habitual use of present tense constructions for FTR may cause speakers to perceive future rewards as temporally closer, and thereby as more valuable. This approach assumes that future tenses primarily encode when an event happens, which overlooks their widespread tendency to encode modal notions of probability. It additionally overlooks the importance of modal expressions in FTR. Since people discount value as a function of both temporal distance and the probability of a reward being received, it is important to understand what different FTR tenses actually encode, as well as cross-linguistic differences in the grammaticization of modality. We therefore modified the EUROTYP questionnaire to elicit future tense as well as modal FTR constructions across a range of temporal distances and probabilities for speakers of English, Dutch, and German. We find that in English tense and probability are more strictly grammaticized than in Dutch or German, and that increasing temporal distance from speaker "now" tended to cause English and German – but not Dutch – speakers to use more uncertain terms. These results highlight the importance of modality for typological linguists working on FTR, and suggest economists working on linguistic relativity and psychological discounting should consider cross-linguistic differences in the grammaticization of modality and in the modal semantics of future tenses.

Effects of early life and current housing on sensitivity to reward loss in a successive negative contrast test in pigs

Animals in a negative affective state seem to be more sensitive to reward loss, i.e. an unexpected decrease in reward size. The aim of this study was to investigate whether early-life and current enriched vs. barren housing conditions affect the sensitivity to reward loss in pigs using a successive negative contrast test. Pigs (n = 64 from 32 pens) were housed in barren or enriched conditions from birth onwards, and at 7 weeks of age experienced either a switch in housing conditions (from barren to enriched or vice versa) or not. Allotting pigs to the different treatments was balanced for coping style (proactive vs. reactive). One pig per pen was trained to run for a large reward and one for a small reward. Reward loss was introduced for pigs receiving the large reward after 11 days (reward downshift), i.e. from then onwards, they received the small reward. Pigs housed in barren conditions throughout life generally had a lower probability and higher latency to get the reward than other pigs. Proactive pigs ran overall slower than reactive pigs. After the reward downshift, all pigs ran slower. Nevertheless, reward downshift increased the latency and reduced the probability to get to the reward, but only in pigs exposed to barren conditions in early life, which thus were more sensitive to reward loss than pigs from enriched early life housing. In conclusion, barren housed pigs seemed overall less motivated for the reward, and early life housing conditions had long-term effects on the sensitivity to reward loss.

Cerebellar climbing fibers encode expected reward size

Climbing fiber inputs to the cerebellum encode error signals that instruct learning. Recently, evidence has accumulated to suggest that the cerebellum is also involved in the processing of reward. To study how rewarding events are encoded, we recorded the activity of climbing fibers when monkeys were engaged in an eye movement task. At the beginning of each trial, the monkeys were cued to the size of the reward that would be delivered upon successful completion of the trial. Climbing fiber activity increased when the monkeys were presented with a cue indicating a large reward, but not a small reward. Reward size did not modulate activity at reward delivery or during eye movements. Comparison between climbing fiber and simple spike activity indicated different interactions for coding of movement and reward. These results indicate that climbing fibers encode the expected reward size and suggest a general role of the cerebellum in associative learning beyond error correction.

Overt attentional capture by reward-related stimuli overcomes inhibitory suppression

Salient-but-irrelevant distractors can automatically capture attention and eye-gaze in visualsearch. However, recent findings have suggested that attention to salient-but-irrelevant stimulican be suppressed when observers use a specific target template to guide their search (i.e.,feature search). A separate line of research has indicated that attentional selection isinfluenced by factors other than the physical salience of a stimulus and the observer’s goals.For instance, pairing a stimulus with reward has been shown to increase the extent to which itcaptures attention and gaze (as though it has become more physically salient), even when suchcapture has negative consequences for the observer. Here we used eye-tracking with arewarded visual search task to investigate whether capture by reward can be suppressed in thesame way as capture by physical salience. When participants were encouraged to use featuresearch, attention to a distractor paired with relatively small reward was suppressed. However,under the same conditions attention was captured by a distractor paired with large reward,even when such capture resulted in reward omission. These findings suggest thatreward-related stimuli are given special priority within the visual attention system over andabove physically-salient stimuli, and have implications for our understanding of real-worldbiases to reward-related stimuli, such as those seen in addiction.

Beyond reach: Do symmetric changes in motor costs affect decision making? A registered report

Executing an important decision can be as easy as moving a mouse cursor or reaching towards the preferred option with a hand. But would we decide differently if choosing required walking a few steps towards an option? More generally, is our preference invariant to the means and motor costs of reporting it? Previous research demonstrated that asymmetric motor costs can nudge the decision-maker towards a less costly option. However, virtually all traditional decision-making theories predict that increasing motor costs symmetrically for all options should not affect choice in any way. This prediction is disputed by the theory of embodied cognition, which suggests that motor behavior is an integral part of cognitive processes, and that motor costs can affect our choices. In this registered report, we investigated whether varying motor costs can affect response dynamics and the final choices in an intertemporal choice task: choosing between a readily available small reward and a larger but delayed reward. Our study compared choices reported by moving a computer mouse cursor towards the preferred option with the choices executed via a more motor costly walking procedure. First, we investigated whether relative values of the intertemporal choice options affect walking trajectories in the same way as they affect mouse cursor dynamics. Second, we tested a hypothesis that, in the walking condition, increased motor costs of a preference reversal would decrease the number of changes-of-mind and therefore increase the proportion of impulsive, smaller-but-sooner choices. We confirmed the hypothesis that walking trajectories reflect covert dynamics of decision making, and rejected the hypothesis that increased motor costs of responding affect decisions in an intertemporal choice task. Overall, this study contributes to the empirical basis enabling the decision-making theories to address the complex interplay between cognitive and motor processes.