The influence of the number of part-set cues on order retention.

Across seven experiments, the present article examined the influence of the number of part-set cues on order retention, as assessed by both reconstruction of order and serial recall tests. Historically, part-set cueing facilitation occurs when half of the items are provided as valid part-set cues on tests of order memory. Using a variety of list lengths (10 or 16), numbers of cues (0-14), and types of cues (full or partial), the present experiments showed disparate effects of the number of part-set cues on reconstruction and serial recall tasks. On reconstruction tests, a minimum number of full cues was required before part-set cueing facilitation was produced and the magnitude of facilitation increased as the number of cues increased. Generally, partial cues did not influence order retention until almost the entire list was provided as partial cues. On serial recall tests, part-set cueing facilitation was only evident with a few full cues. In contrast, part-set cueing impairment was the norm when many partial cues were provided. These results were largely consistent with predictions of the retrieval strategy disruption hypothesis, as well as with an anchoring account of part-set cueing for order.

On the composition of part-set cues.

Two experiments examined whether the specific composition of the set of cues might influence performance on a part-set cueing task. Although researchers traditionally have chosen their part-set cues either at random or systematically across the original set of materials, in the current study, the part-set cues comprised sets of either the most or least memorable items in the stimulus set (based on past research with the materials). With both word list (Experiment 1) and paragraph (Experiment 2) stimuli, the results showed differential effects of cue composition on part-set cueing performance. That is, part-set cueing impairment occurred following the presentation of high memorability cues, whereas there was no difference between cued and uncued performance following presentation of low memorability cues. These results suggest that the presence or absence of part-set cueing impairment can be influenced by the specific composition of the cue set.

Part-set cueing impairment & facilitation in semantic memory.

The present study explored the influence of part-set cues in semantic memory using tests of "free" recall, reconstruction of order, and serial recall. Nine distinct categories of information were used (e.g., Zodiac signs, Harry Potter books, Star Wars films, planets). The results showed part-set cueing impairment for all three "free" recall sets, whereas part-set cueing facilitation was evident for five of the six ordered sets. Generally, the present results parallel those often observed across episodic tasks, which could indicate that similar mechanisms contribute to part-set cueing effects in both episodic and semantic memory. A novel anchoring explanation of part-set cueing facilitation in order and spatial tasks is provided.

Compromising KCC2 transporter activity enhances the development of continuous seizure activity.

Impaired neuronal inhibition has long been associated with the increased probability of seizure occurrence and heightened seizure severity. Fast synaptic inhibition in the brain is primarily mediated by the type A γ-aminobutyric acid receptors (GABAARs), ligand-gated ion channels that can mediate Cl(-) influx resulting in membrane hyperpolarization and the restriction of neuronal firing. In most adult brain neurons, the K(+)/Cl(-) co-transporter-2 (KCC2) establishes hyperpolarizing GABAergic inhibition by maintaining low [Cl(-)]i. In this study, we sought to understand how decreased KCC2 transport function affects seizure event severity. We impaired KCC2 transport in the 0-Mg(2+) ACSF and 4-aminopyridine in vitro models of epileptiform activity in acute mouse brain slices. Experiments with the selective KCC2 inhibitor VU0463271 demonstrated that reduced KCC2 transport increased the duration of SLEs, resulting in non-terminating discharges of clonic-like activity. We also investigated slices obtained from the KCC2-Ser940Ala (S940A) point-mutant mouse, which has a mutation at a known functional phosphorylation site causing behavioral and cellular deficits under hyperexcitable conditions. We recorded from the entorhinal cortex of S940A mouse brain slices in both 0-Mg(2+) ACSF and 4-aminopyridine, and demonstrated that loss of the S940 residue increased the susceptibility of continuous clonic-like discharges, an in vitro form of status epilepticus. Our experiments revealed KCC2 transport activity is a critical factor in seizure event duration and mechanisms of termination. Our results highlight the need for therapeutic strategies that potentiate KCC2 transport function in order to decrease seizure event severity and prevent the development of status epilepticus.

Three Semantic Serial Position Functions at the Same Time.

Serial position functions are so ubiquitous that researchers frequently use buffer items to control for primacy and recency effects regardless of the memory task. However, most theories offer different explanations for different types of tests. In contrast, the relative distinctiveness principle offers one explanation for all tasks: items with fewer close neighbors will generally be more distinct and therefore better remembered than items with more close neighbors. An experiment assessed two predictions of this account. (1) When undergraduates place seven US states in three different orders (by area, year of statehood, and population), serial position functions and error gradients will be observed that resemble those observed in episodic tasks. (2) States that are accurately placed in order because they are an early or late item on one dimension will be placed in order far less accurately when they become mid-list items on a different dimension. The results confirm both predictions.

Spatial part-set cuing facilitation.

Cole, Reysen, and Kelley [2013. Part-set cuing facilitation for spatial information. Journal of Experimental Psychology: Learning, Memory, & Cognition, 39, 1615-1620] reported robust part-set cuing facilitation for spatial information using snap circuits (a colour-coded electronics kit designed for children to create rudimentary circuit boards). In contrast, Drinkwater, Dagnall, and Parker [2006. Effects of part-set cuing on experienced and novice chess players' reconstruction of a typical chess midgame position. Perceptual and Motor Skills, 102(3), 645-653] and Watkins, Schwartz, and Lane [1984. Does part-set cuing test for memory organization? Evidence from reconstructions of chess positions. Canadian Journal of Psychology/Revue Canadienne de Psychologie, 38(3), 498-503] showed no influence of part-set cuing for spatial information when using chess boards. One key difference between the two procedures was that the snap circuit stimuli were explicitly connected to one another, whereas chess pieces were not. Two experiments examined the effects of connection type (connected vs. unconnected) and cue type (cued vs. uncued) on memory for spatial information. Using chess boards (Experiment 1) and snap circuits (Experiment 2), part-set cuing facilitation only occurred when the stimuli were explicitly connected; there was no influence of cuing with unconnected stimuli. These results are potentially consistent with the retrieval strategy disruption hypothesis, as well as the two- and three-mechanism accounts of part-set cuing.

Serial position functions in general knowledge.

Serial position functions with marked primacy and recency effects are ubiquitous in episodic memory tasks. The demonstrations reported here explored whether bow-shaped serial position functions would be observed when people ordered exemplars from various categories along a specified dimension. The categories and dimensions were: actors and age; animals and weight; basketball players and height; countries and area; and planets and diameter. In all cases, a serial position function was observed: People were more accurate to order the youngest and oldest actors, the lightest and heaviest animals, the shortest and tallest basketball players, the smallest and largest countries, and the smallest and largest planets, relative to intermediate items. The results support an explanation of serial position functions based on relative distinctiveness, which predicts that serial position functions will be observed whenever a set of items can be sensibly ordered along a particular dimension. The serial position function arises because the first and last items enjoy a benefit of having no competitors on 1 side and therefore have enhanced distinctiveness relative to mid-dimension items, which suffer by having many competitors on both sides.

A remember-know analysis of the semantic serial position function.

Did the serial position functions observed in certain semantic memory tasks (e.g., remembering the order of books or films) arise because they really tapped episodic memory? To address this issue, participants were asked to make "remember-know" judgments as they reconstructed the release order of the 7 Harry Potter books and 2 sets of movies. For both classes of stimuli, the "remember" and "know" serial position functions were indistinguishable, and all showed the characteristic U-shape with marked primacy and recency effects. These results are inconsistent with a multiple memory systems view, which predicts recency effects only for "remember" responses and no recency effects for "know" responses. However, the data were consistent with a general memory principle account: the relative distinctiveness principle. According to this view, performance on both episodic and semantic memory tasks arises from the same type of processing: Items that are more separated from their close neighbors in psychological space at the time of recall will be better remembered.

The joint influence of collaboration and part-set cueing.

The present study was designed to examine the effects of retrieval cues on memory performance for both individuals and collaborating pairs. Participants worked either alone or together in the presence or absence of part-set cues to recall list items in Experiments 1 and 2 and to reconstruct the order of a list items in Experiment 3. The detrimental effects of collaborative inhibition were observed across all three experiments. In contrast, part-set cueing inhibition was found following free recall, whereas part-set cueing facilitation was observed on reconstruction tasks. Taken together, the results of the present experiments suggest that the effects of collaborative inhibition and part-set cueing may operate independently of one another.

Formation and reactivity of an (alkene)peroxoiridium(III) intermediate supported by an amidinato ligand.

An Ir(I) complex of an acetamidinato ligand was synthesized by reaction of N,N'-diphenylacetamidine, PhN[double bond, length as m-dash]C(Me)NHPh, with either MeLi and [{Ir(cod)}2(µ-Cl)2] or [{Ir(cod)}2(µ-OMe)2] and was characterized by X-ray crystallography as a mononuclear complex, [Ir{PhNC(Me)NPh}(cod)] (1; where cod = 1,5-cyclooctadiene). Reaction of 1 with CO afforded a dinuclear carbonyl complex, [{Ir(CO)2}2{µ-PhNC(Me)NPh-κN:κN'}2] (2), as indicated by EI mass spectrometry and solution- and solid-state IR spectroscopy [νCO (n-pentane) = 2067, 2034 and 1992 cm(-1)]. Activation of O2 by 1 in solution at 20 °C was irreversible and produced an (alkene)peroxoiridium(iii) intermediate, [Ir{PhNC(Me)NPh}(cod)(O2)] (3), which was characterized by one- and two-dimensional NMR techniques and IR spectroscopy (for 3, νOO = 860 cm(-1); for 3-(18)O2, νOO = 807 cm(-1)). Complex 3 oxidized PPh3 to OPPh3, and its decay in the absence of added substrates followed by reaction with cod yielded 4-cycloocten-1-one and a minor amount of 1. In comparison with the results for the previously reported guanidinato complex [Ir{PhNC(NMe2)NPh}(cod)(O2)] (4), the formation of 3 and its reaction with PPh3 are significantly faster, indicating considerable ligand effects in these reactions.

Part-set cuing facilitation for spatial information.

Part-set cuing inhibition refers to the counterintuitive finding that hints--specifically, part of the set of to-be-remembered information--often impair memory performance in free recall tasks. Although inhibition is the most commonly reported result, part-set cuing facilitation has been shown with serial order tasks. The present study examined the influence of part-set cuing for spatial locations using novel methods and materials. Participants viewed the construction of Snap Circuit objects and then attempted to reconstruct the objects in either the presence or absence of part-set cues. Two experiments revealed robust part-set cuing facilitation on the spatial memory tasks. Generally, these results are consistent with the predictions of the retrieval strategy disruption hypothesis (e.g., D. R. Basden & Basden, 1995) and the 2- and 3-mechanism accounts of part-set cuing (Bäuml & Aslan, 2006; Bäuml & Samenieh, 2012).

Guanidinato complexes of iridium: ligand-donor strength, O2 reactivity, and (alkene)peroxoiridium(III) intermediates.

A series of seven [Ir{ArNC(NR2)NAr}(cod)] complexes (1a-1g; where R = Me or Et; Ar = Ph, 4-MeC6H4, 4-MeOC6H4, 2,6-Me2C6H3, or 2,6-(i)Pr2C6H3; and cod = 1,5-cyclooctadiene) were synthesized by two different methods from the neutral guanidines, ArN═C(NR2)NHAr, using either MeLi and [{Ir(cod)}2(µ-Cl)2] or [{Ir(cod)}2(µ-OMe)2]. Reaction of 1a-1g with CO produced the corresponding [Ir{ArNC(NR2)NAr}(CO)2] complexes (2a-2g), which were characterized by NMR and solution- and solid-state IR spectroscopy. Complexes 1b (R = Et, Ar = Ph), 1d (R = Et, Ar = 4-MeC6H4), 1f (R = Me, Ar = 2,6-Me2C6H3), and 2b (R = Et, Ar = Ph) were characterized by X-ray crystallography as mononuclear complexes with a guanidinato-κ(2)N,N' ligand and a cod or two CO ligands coordinated to the Ir center in a distorted square-planar environment. On the basis of the CO stretching frequencies of 2a-2g [avg. νCO (n-pentane) = 2016-2019 cm(-1)] and the alkene (13)C chemical shifts of 1a-1g [δ((13)CC═C) = 58.7-61.0 ppm], the donor strength of the guanidinato ligands was evaluated and compared to that of related monoanionic ligands. Reaction of 1a-1g in solution with O2 at 20 °C afforded (alkene)peroxoiridium(III) intermediates, [Ir{ArNC(NR2)NAr}(cod)(O2)] (3). The steric properties of the supporting ligand play a decisive role in O2 binding in that complexes without ortho substituents react largely irreversibly with O2 (1a-1e; where Ar = Ph, 4-MeC6H4 or 4-MeOC6H4), whereas complexes with ortho substituents exhibit fully reversible O2 binding (1f and 1g; where Ar = 2,6-Me2C6H3 or 2,6-(i)Pr2C6H3). Complexes 3a-3f were characterized by (1)H NMR and IR spectroscopy (νOO = 857-872 cm(-1)). Decay of the new intermediates and subsequent reaction with cod produced 4-cycloocten-1-one and the respective Ir(I) precursor.

Three more semantic serial position functions and a SIMPLE explanation.

There are innumerable demonstrations of serial position functions-with characteristic primacy and recency effects-in episodic tasks, but there are only a handful of such demonstrations in semantic memory tasks, and those demonstrations have used only two types of stimuli. Here, we provide three more examples of serial position functions when recalling from semantic memory. Participants were asked to reconstruct the order of (1) two cartoon theme song lyrics, (2) the seven Harry Potter books, and (3) two sets of movies, and all three demonstrations yielded conventional-looking serial position functions with primacy and recency effects. The data were well-fit by SIMPLE, a local distinctiveness model of memory that was originally designed to account for serial position effects in short- and long-term episodic memory. According to SIMPLE, serial position functions in both episodic and semantic memory tasks arise from the same type of processing: Items that are more separated from their close neighbors in psychological space at the time of recall will be better remembered. We argue that currently available evidence suggests that serial position functions observed when recalling items that are presumably in semantic memory arise because of the same processes as those observed when recalling items that are presumably in episodic memory.

Evidence for a reactive (alkene)peroxoiridium(III) intermediate in the oxidation of an alkene complex with O2.

An (alkene)peroxoiridium(III) complex, [Ir(L)(cod)(O(2))] [where LH = PhN=C(NMe(2))NHPh and cod = 1,5-cyclooctadiene], was identified as an intermediate in the reaction of the Ir(I) precursor [Ir(L)(cod)] with O(2) and characterized by spectroscopic methods. Decay of the intermediate and further reaction with 1,5-cyclooctadiene produced 4-cycloocten-1-one.

The effects of collaboration on recall of social information.

Three experiments examined the effects of passage type on both individual and collaborative memory performance. In Experiment 1, both individuals and collaborative groups recalled more information from passages containing social information than non-social information. Furthermore, collaborative inhibition (CI) was observed for both types of passages. In Experiment 2, which included a social passage that did not contain gossip, significant main effects of both gossip (gossip > non-gossip) and sociability (explicit > implicit) were observed. As in Experiment 1, CI was observed across all conditions. Experiment 3 separately manipulated gossip and the interest level of the passages and both of these factors enhanced memory performance. Moreover, robust CI was again observed across all conditions. Taken together, the present results demonstrate a mnemonic benefit for social information in individuals and collaborative groups.

Obtaining representative nominal groups.

Many researchers studying the effectiveness of working in groups have compared group performance with the scores of individuals combined into nominal groups. Traditionally, methods for forming nominal groups have been shown to be poor, and more recent procedures (Wright, 2007) are difficult to use for complex designs and are inflexible. A new procedure is introduced and tested in which thousands of possible combinations of nominal groups are sampled. Sample characteristics, such as the mean, variance, and distribution, of all these sets are calculated, and the set that is most representative of all of these sets is returned. The user can choose among different ways of conceptualizing the meaning of most representative, but on the basis of simulations and the fact that most subsequent statistical procedures are based on the mean and variance, we argue that finding the set with the mean and variance most similar to the means of the representative statistics for all of the sets is the preferred approach. The algorithm is implemented in a stand-alone C++ executable program and as an R function. Both of these allow anyone to use the procedures freely.

Synthesis, characterization, and O2 reactivity of iridium(I) complexes supported by guanidinato ligands.

Mononuclear [Ir{ArNC(NR(2))NAr}(C(8)H(12))] complexes (where R = Me or Et; Ar = Ph, 4-MeC(6)H(4), or 2,6-Me(2)C(6)H(3); and C(8)H(12) = 1,5-cyclooctadiene) were synthesized from the neutral N,N-dialkyl-N',N''-diarylguanidines via deprotonation and transmetalation. As confirmed by single-crystal structure determinations, the guanidinato(1-) ligands coordinate the low-valent d(8) Ir(I) center in an N,N'-chelating binding mode, and the (13)C NMR chemical shifts of the alkene carbon atoms establish that these ligands function as stronger donors than related monoanionic, bidentate nitrogen-based ligands. In the reactions of the complexes with O(2), the observed reactivity trends correlate with the electronic and steric influences of the substituents of the guanidinato ligands.

Repeated questioning for order of events: disparate effects following logical versus random presentation.

In the present study, 72 college-age participants from an introductory psychology course viewed a series of 20 pictures depicting events surrounding a routine activity, i.e., eating at a cafeteria; these pictures were presented either in a logical order. e.g., enter cafeteria, pick up tray, stand in line, and select food, or in a random order. Three successive tests of free reconstruction of order indicated disparate effects of these conditions; random presentation produced significant forgetting of order information across tests, whereas logical presentation produced no change in performance across tests. Whereas randomly presented stimuli produced both reliable intertest recovery (reminiscence) and forgetting, neither result was observed following logical presentation. The implications of these data for eyewitness testimony for general theories of hypermnesia are discussed.

Fill-in and infill errors in order memory.

Many current models of memory are specified with enough detail to make predictions about patterns of errors in memory tasks. However, there are often not enough empirical data available to test these predictions. We report two experiments that examine the relative frequency of fill-in and infill errors. In immediate serial recall tasks, subjects sometimes incorrectly recall item N too soon, placing it in position N-1. The error of interest is which item is recalled after this initial mistake. A fill-in error is the tendency to recall item N-1 next, whereas an infill error is the tendency to recall item N+1 next. Both experiments reveal more fill-in than infill errors, not only overall but at each possible error location throughout the list. The overall ratio is approximately 2:1. We conclude that none of the currently existing models adequately accounts for fill-in and infill errors.

Remembering the forgotten? Reminiscence, hypermnesia and memory for order.

Three experiments established that repeated testing affects item and order retention differently: Hypermnesia was found with repeated free recall tests, whereas net performance declined significantly across successive free reconstruction of order tests. Overall order performance declined over tests under a variety of encoding conditions (pictures, words, and relational and item-specific processing) and retrieval conditions (intentional and incidental learning). Although net performance dropped across tests, participants did show reliable order recovery (reminiscence) between tests. The implications of these data for general theories of hypermnesia and order are discussed.