Long-term memory of pigeons for stimulus-outcome associations involving multiple stimuli, each seen in a single brief trial

Experiment 1 explored performance of pigeons in two versions of a shortterm recognition memory procedure. In one version responding to entirely novel slides was rewarded, and responding to familiar slides (slides seen once, for 10 sec) was not rewarded; in the other version, responding to familiar slides was rewarded. Performance was initially below chance in both versions of the procedure. This result indicated that in this procedure associations were formed between the slides and the outcome (reward or non-reward) that followed their presentation. The result also suggested that the true capacity of pigeon recognition memory cannot be assessed using these procedures, as performance is inevitably disrupted by the bird's associative memory. The tendency of pigeons to form one-trial associations was exploited in Experiment 2. Phase 1 consisted of 16 two-session cycles: in Session 1 of each cycle, birds were shown 20 novel slides and were rewarded for responding to 10 of those slides; in Session 2, the same slides were shown again, with the same reinforcement contingencies. The birds showed significant overnight retention of the one-trial associations formed in Session 1 of each cycle. Phase 2 showed significant retention over periods of more than 20 days of associations involving 320 slides seen twice only. Phase 3 re-exposed for nine daily sessions one of the sets of 20 slides used in Phases 1 and 2; a high level of discrimination emerged rapidly and 4 (of 8) birds showed, by the end of training, no overlap in response rates to positive and negative slides. Comparative implications of the results are discussed.     

Where’s the difficulty in standardized reading tests: The passage or the question?

The purpose of this investigation was to examine the extent to which item and text characteristics predict item difficulty on the comprehension portion of the Gates-MacGinitie Reading Tests for the 7th–9th and 10th–12th grade levels. Detailed item-based analyses were performed on 192 comprehension questions on the basis of the cognitive processing model framework proposed by Embretson and colleagues (Embretson & Wetzel, 1987). Item difficulty was analyzed in terms of various passage features (e.g., word frequency and number of propositions) and individual-question characteristics (e.g., abstractness and degree of inferential processing), using hierarchical linear modeling. The results indicated that the difficulty of the items in the test for the 7th–9th grade level is primarily influenced by text features—in particular, vocabulary difficulty—whereas the difficulty of the items in the test for the 10th–12th grade level is less systematically influenced by text features.     

The role of temporal intervals on reinforcer accumulation

Animals accumulate reinforcers when they forgo the opportunity to consume available food in favor of acquiring additional food for later consumption. Laboratory research has shown that reinforcer accumulation is facilitated when an interval (either spatial or temporal) separates earning from consuming reinforcers. However, there has been no systematic investigation on the interval separating consuming reinforcers from earning additional reinforcers. This oversight is problematic because this second interval is an integral part of much of the previous research on reinforcer accumulation. The purpose of the current study was to determine the independent contributions of these two temporal intervals on reinforcer accumulation in rats. Each left lever press earned a single food pellet; delivery of the accumulated pellet(s) occurred upon a right lever press. Conditions varied based on the presence of either an intertrial interval (ITI) that separated pellet delivery from the further opportunity to accumulate more pellets, or a delay‐to‐reinforcement that separated the right lever press from the delivery of the accumulated pellet(s). Delay and ITI values of 0, 5, 10 and 20 s were investigated. The delay‐to‐reinforcement conditions produced greater accumulation relative to the ITI conditions, despite accumulation increasing the density of reinforcement more substantially in the ITI conditions. This finding suggests that the temporal separation between reinforcer accumulation and subsequent delivery and consumption was a more critical variable in controlling reinforcer accumulation.     

The Stoplight Task: A Procedure for Assessing Risk Taking in Humans

The Psychological Record - The Stoplight Task, a procedure involving a computer analog of a stoplight, was evaluated for assessing risk taking in humans. Seventeen participants earned points later...     

The effect of different soothing interventions on infant crying and on parent–infant interaction

Conducted in the home environment, this study examines the effects of three complementary soothing techniques on the duration of infant crying and on caregiver–infant interaction. In one group, the caregivers apply massage; in another, they provide supplemental carrying to their infants, and in the last, the caregivers both massage and provide supplemental carrying. Measurements, for the one control and three treatment groups took place prenatally (third trimester) and in the first 16 weeks postpartum for parental perception of infant temperament, parental sense of competence, parent–infant interaction, and the duration of infant crying. Whereas analyses indicate no statistically significant differences between groups in reducing infant crying, results approached significance (p ≤ .06) in favor of the combined supplemental carrying/massage group. These results challenge accepted beliefs that tactile stimulation and/or supplemental carrying enhance parental sense of competence, positive parental perceptions, and interactions with infants. Practitioners can apply these conclusions when counselling parents on the advisability of selecting any one complementary soothing technique. ©2002 Michigan Association for Infant Mental Health.     

An introduction to hearing loss and screening procedures for behavioral research

Hearing loss is a confounding variable that is rarely addressed in behavioral research despite its prevalence across the life span. Currently, the most common method of experimental control over hearing acuity is through self report of perceived impairment. We argue that this technique may lack sensitivity and that researchers should more commonly utilize standardized hearing screening procedures. Distinctive patterns of hearing loss are reviewed with attention to populations that commonly participate in behavioral research. We explain standard techniques for conducting pure tone hearing screening using a conventional portable audiometer and outline a procedure for how researchers can modify a conventional laptop computer for audiometric screening when a standard audiometer is unavailable. We offer a sample hearing screening program that researchers may use toward the development of their own protocol. This program is freely available for download at www .psychonomic.org/archive.     

Developing PFC representations using reinforcement learning

From both functional and biological considerations, it is widely believed that action production, planning, and goal-oriented behaviors supported by the frontal cortex are organized hierarchically [Fuster (1991); Koechlin, E., Ody, C., & Kouneiher, F. (2003). Neuroscience: The architecture of cognitive control in the human prefrontal cortex. Science, 424, 1181-1184; Miller, G. A., Galanter, E., & Pribram, K. H. (1960). Plans and the structure of behavior. New York: Holt]. However, the nature of the different levels of the hierarchy remains unclear, and little attention has been paid to the origins of such a hierarchy. We address these issues through biologically-inspired computational models that develop representations through reinforcement learning. We explore several different factors in these models that might plausibly give rise to a hierarchical organization of representations within the PFC, including an initial connectivity hierarchy within PFC, a hierarchical set of connections between PFC and subcortical structures controlling it, and differential synaptic plasticity schedules. Simulation results indicate that architectural constraints contribute to the segregation of different types of representations, and that this segregation facilitates learning. These findings are consistent with the idea that there is a functional hierarchy in PFC, as captured in our earlier computational models of PFC function and a growing body of empirical data.