Learning in cod (Gadus morhua): long trace interval retention

Basic knowledge about learning capacities and awareness in fish is lacking. In this study we investigated which temporal gaps Atlantic cod could tolerate between two associated events, using an appetitive trace-conditioning paradigm with blinking light as conditioned stimulus (CS) and dry fish food as unconditioned stimulus (US). CS–US presentations were either temporally overlapping (delay conditioning, CS duration 24 s, interstimulus interval 12 s) or separated by 20, 60, or 120 s (trace conditioning, CS duration 12 s) or 2 h (control, CS duration 12 s). The percentage of fish in the feeding area increased strongly during CS presentation in all delay, 20 s, and 60 s trace groups and in one out of two 120 s trace groups, but not in the control groups. In the 20 and 60 s trace procedures, the fish crowded together in the small feeding area during the trace interval, showing strong anticipatory behaviour. In all the conditioned groups, the fish responded to the CS within eight trials, demonstrating rapid learning. At 88 and 70 days after the end of the conditioning experiments, the delay and 20 s trace groups, respectively, were presented the CS six times at 2-h intervals without reward. All groups responded to the light signal, demonstrating memory retention after at least 3 months. This study demonstrates that Atlantic cod has an impressively good ability to associate two time-separated events and long time retention of learnt associations.     

Maternal well-being and sleep–wake behaviors in infants: An intervention using maternal odor

The development of an organized sleep–wake cycle in young infants is influenced by characteristics of both the infant and the parent, and by the nature of their dyadic interaction. Sleep–wake state organization is influenced first by homeostatic biological regulation, and later by socioemotional regulation. This report describes a feasibility study using an olfactory intervention designed to bridge the transition from physiologic to social regulation in sleep–wake state organization. A sample of 21 mother–infant dyads participated in an one year longitudinal study, after random assignment to either an experimental condition with a maternal odor-laden sleepaid, representational sleepaid (RSA) or a control condition with a neutral sleepaid, Sham Control (SC). Self-report questionnaires measured maternal psychological well-being, and video taping recorded infant sleep–wake behaviors repeatedly throughout the first year. RSA mothers reported significantly better levels of well-being throughout the year. At six and twelve months, mothers who reported more depressive feelings exhibited different nighttime interaction patterns. Infant sleep–wake state organization and sleepaid use changed significantly during the first year but were not altered by the intervention. © 1997 Michigan Association for Infant Mental Health     

Correction to: Non-transitive Better than Relations and Rational Choice

Philosophia - There is a mistake in the definition of the covering criterion on page 6.     

Preference or ability: Exploring the relations between risk preference,personality, and cognitive abilities

Key issues in the behavioral sciences are if there exist stable risk preferences that generalize across domains and if these are best measured by revealed risk preference (RRP) in behavioral decision tasks or by surveys eliciting stated risk preference (SRP). We applied network analysis to data from a representative Swedish sample to investigate the relations between RRP, SRP, personality characteristics, and cognitive abilities, using in total over 70 measurements. The results showed that different measures of RRP were poorly intercorrelated and formed a community together with measures of numerical and cognitive abilities. Measures of SRP were weakly correlated with measures of RRP and identified in a distinctly separate community, along with personality characteristics and gender. The ensuing analyses provided support for a model suggesting that RRPs are contaminated by demands on numerical and cognitive abilities. RRPs may thus suffer from poor construct validity, whereas SRPs may better capture people's everyday risk preferences because they are related to more stable traits.     

A gentle reminder that mean does not imply modal behavior: Few are in-group biased in minimal groups

Previous research reports that people organized into newly formed, arbitrary groups (i.e., minimal groups) are on average in-group biased. However, that people on average behave in a certain way does not imply that most people behave that way. Here, I report four studies (n = 224) demonstrating in-group biased average behaviors driven by a minority of about 30% participants. Further, only 14% reported allocating resources in a group-biased manner because they “favored the in-group.” I investigate and discuss how methodological issues related to non-normally distributed data, not taking participants’ intentions into account, and using fixed response matrices can lead to overestimations of how widespread in-group bias is in minimal groups.     

Expansion of arbitrary stimulus classes and function-transfer measured by sorting performances

Sorting (SRT) and matching-to-sample (MTS) tests have measured the formation of arbitrary stimulus classes. This experiment used SRT and MTS tests to document the expansion of class size. Thirty-two participants learned 12 conditional discriminations with a linear series training structure (A➔B➔C➔D➔E). SRT tests documented the formation of 5-member classes by 17 of the participants. Thereafter, 6-member class expansion was implemented by FC training. Nine of these 17 participants showed class expansion when tracked with a sequence of an SRT, MTS, and a final SRT test, and the other 8 showed expansion when tracked with a sequence of MTS and SRT tests. Thus, SRT tests documented class expansion, and the sequence of tests did not influence class expansion. The 15 participants who did not form the 5-member classes learned the baselines for new 3-member classes (A➔B➔C) and formed them as documented by an SRT test. Then, 4-member class expansion was implemented by FB training. Expansion was assessed using the above-mentioned testing sequences. All 15 showed class expansion with 100% correspondence between the SRT and MTS performances. Sorting documented the expansion of arbitrary stimulus classes, while the MTS tests showed that the stimuli also functioned as members of equivalence classes.     

Intelligence and executive functioning in adult age: Effects of sibship size and birth order

Several studies have demonstrated that social influences from having been brought up in a family with few siblings and early in birth order result in higher scores on intelligence tests in childhood and adolescence as compared to having been brought up in large sibships. The present study examined whether influences of such social factors would have long-lasting effects on intelligence (block design and word comprehension) and executive functions (working memory and verbal fluency) in adulthood and old age, i.e., long after the individuals had moved out of the family structure they were born in. After having controlled for socioeconomic status and a variety of health conditions affecting cognition in adult life, a sibship size effect was demonstrated for executive functions but not for intelligence. The social influences of birth order affected only executive functions and working memory in particular; earlier born individuals performed better than later born individuals in tests assessing executive function but not in tests assessing intelligence. Implications for the relationship between executive functioning and intelligence, and implications for the Confluence and Resource Dilution Models (Blake, 1981; Downey, 1995, 2001; Zajonc, 1976) are discussed.