Implicit sequence learning in ring‐tailed lemurs (Lemur catta)

Implicit learning involves picking up information from the environment without explicit instruction or conscious awareness of the learning process. In nonhuman animals, conscious awareness is impossible to assess, so we define implicit learning as occurring when animals acquire information beyond what is required for successful task performance. While implicit learning has been documented in some nonhuman species, it has not been explored in prosimian primates. Here we ask whether ring‐tailed lemurs (Lemur catta) learn sequential information implicitly. We tested lemurs in a modified version of the serial reaction time task on a touch screen computer. Lemurs were required to respond to any picture within a 2 × 2 grid of pictures immediately after its surrounding border flickered. Over 20 training sessions, both the locations and the identities of the images remained constant and response times gradually decreased. Subsequently, the locations and/or the identities of the images were disrupted. Response times indicated that the lemurs had learned the physical location sequence required in original training but did not learn the identity of the images. Our results reveal that ring‐tailed lemurs can implicitly learn spatial sequences, and raise questions about which scenarios and evolutionary pressures give rise to perceptual versus motor‐implicit sequence learning.     

Control by reinforcers across time and space: A review of recent choice research

Reinforcers affect behavior. A fundamental assumption has been that reinforcers strengthen the behavior they follow, and that this strengthening may be context‐specific (stimulus control). Less frequently discussed, but just as evident, is the observation that reinforcers have discriminative properties that also guide behavior. We review findings from recent research that approaches choice using nontraditional procedures, with a particular focus on how choice is affected by reinforcers, by time since reinforcers, and by recent sequences of reinforcers. We also discuss how conclusions about these results are impacted by the choice of measurement level and display. Clearly, reinforcers as traditionally considered are conditionally phylogenetically important to animals. However, their effects on behavior may be solely discriminative, and contingent reinforcers may not strengthen behavior. Rather, phylogenetically important stimuli constitute a part of a correlated compound stimulus context consisting of stimuli arising from the organism, from behavior, and from physiologically detected environmental stimuli. Thus, the three‐term contingency may be seen, along with organismic state, as a correlation of stimuli. We suggest that organisms may be seen as natural stimulus‐correlation detectors so that behavioral change affects the overall correlation and directs the organism toward currently appetitive goals and away from potential aversive goals. As a general conclusion, both historical and recent choice research supports the idea that stimulus control, not reinforcer control, may be fundamental.     

Effects of signaling on temporal control of behavior in response‐initiated fixed intervals

Behavior and events distributed in time can serve as markers that signal delays to future events. The majority of timing research has focused on how behavior changes as the time to some event, usually food availability, decreases. The primary objective of the two experiments presented here was to assess how behavior changes as time passes between two time markers when the first time marker was manipulated but the second, food delivery, was held constant. Pigeons were exposed to fixed‐interval, response‐initiated fixed‐interval, and signaled response‐initiated fixed‐interval 15‐ and 30‐s schedules of reinforcement. In Experiment 1, first‐response latencies were systematically shorter in the signaled response‐initiated schedules than response‐initiated schedules, suggesting that the first response was a more effective time marker when it was signaled. In Experiment 2, responding in no‐food (i.e. “peak”) trials indicated that timing accuracy was equivalent in the three schedule types. Compared to fixed interval schedules, timing precision was reduced in the signaled response‐initiated schedules and was lowest in response‐initiated schedules. Results from Experiments 1 and 2 coupled with previous research suggest that the overall “informativeness” of a time marker relative to other events and behaviors in the environment may determine its efficacy.     

Should One Be A Left or A Right Sellarsian? (And is There Really Such A Choice?)

The followers of Wilfrid Sellars are often divided into “right” and “left” Sellarsians, according to whether they believe, in Mark Lance's words, that “linguistic roles constitutive of meaning and captured by dot quoted words are ‘normative all the way down.’” The present article anatomizes this division and argues that it is not easy to give it a nontrivial sense. In particular, the article argues that it is not really possible to construe it as a controversy related to ontology, and goes on to argue that it is also not easy to construe it as one concerning the translatability of the normative idiom into the non‐normative one. The conclusion is that the only coherent interpretation of this disagreement is as a disagreement about the possibility and desirability of assuming a standpoint “inside” our linguistic practices.     

The role of ecological validity in hazard perception assessment

Hazard perception is one of the few quantifiable components of driving competency that can explain the high crash risk of novice drivers (see Horswill & McKenna, 2004). Some studies focused on investigating the stimulus part of hazard perception items by comparing several design features of the displayed traffic scenarios (e.g. Malone et al., 2012; Scialfa et al., 2013). Other empirical studies have been conducted to address the reaction part of hazard perception items (e.g. Vlakveld, 2014). Among others, existing hazard perception tests differ with respect to the ecological validity – the similarity to real-world demands – of the task that has to be completed by the participants (simple reaction, hazard localization, simulated driving, etc.). Based on the findings of general expertise research (see Glaser & Chi, 1988), the hypothesis of the present experiment was that an increased ecological validity of a hazard perception task has a positive effect on the magnitude of performance differences between more and less experienced drivers. 104 learner drivers and 51 experienced drivers were randomly assigned either to a less ecological valid version (multiple choice task) or a higher ecological valid version (reaction task) of a hazard perception test. In both conditions, the same 20 animated hazardous or non-hazardous traffic scenarios were presented. Overall, the experienced drivers outperformed the learner drivers. Principally, both of the applied versions of the test provided a criterion valid measure of driving expertise. However, increasing the ecological validity of the test by using a reaction task was especially beneficial for certain types of scenarios, leading to higher expertise-related differences. In addition, the reaction task provides response time measure as a further valid performance indicator. This allows the identification of those participants who are indeed able to detect a hazard in a certain scenario, but still have deficits in response time, compared to more experienced drivers. According to the present study, it is recommended to choose the reaction task over the multiple choice task to test hazard perception. Whether a further increase in ecological validity of the task would be useful, should be tested empirically in future research.     

An improved spatial span test of visuospatial memory

In the widely used Corsi Block Test and Wechsler Spatial Span Tests, participants must reproduce sequences of blocks in the order touched by the examiner until two trials are missed at the same sequence length. The examiner records either the maximum number of blocks correctly reported or the total number of correct lists. Here, we describe a computerized spatial span test (C-SST) that uses psychophysical procedures to quantify visuospatial mean span (MnS) with sub-digit precision. Results from 187 participants ranging in age from 18 to 82 years showed that accuracy declined gradually with list length around the MnS (by ～30% per item). Simulation studies revealed high variance and biases in CBT and Wechsler measures, and demonstrated that the C-SST provided the most accurate estimate of true span (i.e., the sequence length producing 50% correct). MnS declined more rapidly with age than mean digit span (MnDS) measured in the same participants. Response times correlated with both MnS and MnDS scores. Error analysis showed that omission and transposition errors predominated, with weaker primacy and recency effects in spatial span than digit span testing. The C-SST improves the precision of spatial span testing and reveals significant differences between visuospatial and verbal working memory.     

Frequency,characteristics, and perceived functions of emotional future thinking in daily life

While many thoughts and mental images that people form about their personal future refer to emotionally significant events, there is still little empirical data on the frequency and nature of emotional future-oriented thoughts (EmoFTs) that occur in natural settings. In the present study, participants recorded EmoFTs occurring in daily life and rated their characteristics, emotional properties, and perceived functions. The results showed that EmoFTs are frequent, occur in various contexts, and are perceived to fulfil important functions, mostly related to goal pursuit and emotion regulation. When distinguishing between anticipatory and anticipated emotions (i.e., emotions experienced in the present versus emotions expected to occur in the future), a positivity bias in the frequency of EmoFTs was found to be restricted to anticipated emotions. The representational format and perceived function of EmoFTs varied according to their affective valence, and the intensity of anticipatory and anticipated emotions were influenced by the personal importance and amount of visual imagery of EmoFTs. Mood states preceding EmoFTs influenced their emotional components, which, in turn, impacted ensuing mood states. Overall, these findings shed further light on the emotional properties of future-oriented thoughts that are experienced in daily life.     

Visual perspective in remembering and episodic future thought

According to the constructive episodic simulation hypothesis, remembering and episodic future thinking are supported by a common set of constructive processes. In the present study, we directly addressed this assertion in the context of third-person perspectives that arise during remembering and episodic future thought. Specifically, we examined the frequency with which participants remembered past events or imagined future events from third-person perspectives. We also examined the different viewpoints from which third-person perspective events were remembered or imagined. Although future events were somewhat more likely to be imagined from a third-person perspective, the spatial viewpoint distributions of third-person perspectives characterizing remembered and imagined events were highly similar. These results suggest that a similar constructive mechanism may be at work when people remember events from a perspective that could not have been experienced in the past and when they imagine events from a perspective that could not be experienced in the future. The findings are discussed in terms of their consistency with—and as extensions of—the constructive episodic simulation hypothesis.