Enhanced memory for context associated with corrective feedback: evidence for episodic processes in errorful learning.

Numerous studies have established that there are benefits of corrective feedback for learning, but the mechanisms of this benefit are not well understood. An important question is whether corrective feedback improves memory via episodic processes or solely via semantic mediation. If episodic processes are involved, then memory for corrective feedback should include contextual details of the feedback episode. The present study tested this hypothesis across 3 experiments (total n = 223) in which participants completed an encoding task that involved cued guessing of category exemplars. Exemplars generated by participants were equally likely to be treated as correct or incorrect, and the "correct" exemplar was presented within a feedback display after each response. Separate versions of the task manipulated font colour in either the feedback display or the initial cue/typed response display. Participants were instructed to remember either the correct exemplars or their own typed responses, and the corresponding font colours. Retrieval task (cued recall, free recall, recognition) was varied across experiments. Across all 3 experiments, a higher rate of memory accuracy was observed for context associated with corrective feedback relative to other conditions. The findings are consistent with the hypothesis that errorful learning involves episodic memory, not merely semantic mediation.

Cortical Auditory Event-Related Potentials and Categorical Perception of Voice Onset Time in Children With an Auditory Neuropathy Spectrum Disorder.

Objective: This study evaluated cortical encoding of voice onset time (VOT) in quiet and noise, and their potential associations with the behavioral categorical perception of VOT in children with auditory neuropathy spectrum disorder (ANSD). Design: Subjects were 11 children with ANSD ranging in age between 6.4 and 16.2 years. The stimulus was an /aba/-/apa/ vowel-consonant-vowel continuum comprising eight tokens with VOTs ranging from 0 ms (voiced endpoint) to 88 ms (voiceless endpoint). For speech in noise, speech tokens were mixed with the speech-shaped noise from the Hearing In Noise Test at a signal-to-noise ratio (SNR) of +5 dB. Speech-evoked auditory event-related potentials (ERPs) and behavioral categorization perception of VOT were measured in quiet in all subjects, and at an SNR of +5 dB in seven subjects. The stimuli were presented at 35 dB SL (re: pure tone average) or 115 dB SPL if this limit was less than 35 dB SL. In addition to the onset response, the auditory change complex (ACC) elicited by VOT was recorded in eight subjects. Results: Speech evoked ERPs recorded in all subjects consisted of a vertex positive peak (i.e., P1), followed by a trough occurring approximately 100 ms later (i.e., N2). For results measured in quiet, there was no significant difference in categorical boundaries estimated using ERP measures and behavioral procedures. Categorical boundaries estimated in quiet using both ERP and behavioral measures closely correlated with the most-recently measured Phonetically Balanced Kindergarten (PBK) scores. Adding a competing background noise did not affect categorical boundaries estimated using either behavioral or ERP procedures in three subjects. For the other four subjects, categorical boundaries estimated in noise using behavioral measures were prolonged. However, adding background noise only increased categorical boundaries measured using ERPs in three out of these four subjects. Conclusions: VCV continuum can be used to evaluate behavioral identification and the neural encoding of VOT in children with ANSD. In quiet, categorical boundaries of VOT estimated using behavioral measures and ERP recordings are closely associated with speech recognition performance in children with ANSD. Underlying mechanisms for excessive speech perception deficits in noise may vary for individual patients with ANSD.

Modeling age differences in effects of pair repetition and proactive interference using a single parameter.

In this article, we apply the REM model (Shiffrin & Steyvers, 1997) to age differences in associative memory. Using Criss and Shiffrin's (2005) associative version of REM, we show that in a task with pairs repeated across 2 study lists, older adults' reduced benefit of pair repetition can be produced by a general reduction in the diagnosticity of information stored in memory. This reduction can be modeled similarly well by reducing the overall distinctiveness of memory features, or by reducing the accuracy of memory encoding. We report a new experiment in which pairs are repeated across 3 study lists and extend the model accordingly. Finally, we extend the model to previously reported data using the same task paradigm, in which the use of a high-association strategy introduced proactive interference effects in young adults but not older adults. Reducing the diagnosticity of information in memory also reduces the proactive interference effect. Taken together, the modeling and empirical results reported here are consistent with the claim that some age differences that appear to be specific to associative information can be produced via general degradation of information stored in memory. The REM model provides a useful framework for examining age differences in memory as well as harmonizing seemingly conflicting prior modeling approaches for the associative deficit. (PsycINFO Database Record

A Positive Generation Effect on Memory for Auditory Context.

Self-generation of information during memory encoding has large positive effects on subsequent memory for items, but mixed effects on memory for contextual information associated with items. A processing account of generation effects on context memory (Mulligan in Journal of Experimental Psychology: Learning, Memory, and Cognition, 30(4), 838-855, 2004; Mulligan, Lozito, & Rosner in Journal of Experimental Psychology: Learning, Memory, and Cognition, 32(4), 836-846, 2006) proposes that these effects depend on whether the generation task causes any shift in processing of the type of context features for which memory is being tested. Mulligan and colleagues have used this account to predict various negative effects of generation on context memory, but the account also predicts positive generation effects under certain circumstances. The present experiment provided a critical test of the processing account by examining how generation affected memory for auditory rather than visual context. Based on the processing account, we predicted that generation of rhyme words should enhance processing of auditory information associated with the words (i.e., voice gender), whereas generation of antonym words should have no effect. These predictions were confirmed, providing support to the processing account.

Compensation for visually specified coarticulation in liquid-stop contexts.

The question of whether speech perceivers use visual coarticulatory information in speech perception remains unanswered, despite numerous past studies. Across different coarticulatory contexts, studies have both detected (e.g., Mitterer in Perception & Psychophysics, 68, 1227-1240, 2006) and failed to detect (e.g., Vroomen & de Gelder in Language and Cognitive Processes, 16, 661-672. doi: 10.1080/01690960143000092 , 2001) visual effects. In this study, we focused on a liquid-stop coarticulatory context and attempted to resolve the contradictory findings of Fowler, Brown, and Mann (Journal of Experimental Psychology: Human Perception and Performance, 26, 877-888. doi: 10.1037/0096-1523.26.3.877 , 2000) and Holt, Stephens, and Lotto (Perception & Psychophysics, 67, 1102-1112. doi: 10.3758/BF03193635 , 2005). We used the original stimuli of Fowler et al. with modifications to the experimental paradigm to examine whether visual compensation can occur when acoustic coarticulatory information is absent (rather than merely ambiguous). We found that perceivers' categorizations of the target changed when coarticulatory information was presented visually using a silent precursor, suggesting that visually presented coarticulatory information can induce compensation. However, we failed to detect this effect when the same visual information was accompanied by an ambiguous auditory precursor, suggesting that these effects are weaker and less robust than auditory compensation. We discussed why this might be the case and examined implications for accounts of coarticulatory compensation.

Evidence of novel plant-species specific ammonia oxidizing bacterial clades in acidic South African fynbos soils.

Ammonia-oxidizing bacteria (AOB) are essential in the biogeochemical cycling of nitrogen as they catalyze the rate-limiting oxidation of ammonia into nitrite. Since their first isolation in the late 19th century, chemolithoautotrophic AOBs have been identified in a wide range of natural (e.g., soils, sediments, estuarine, and freshwaters) and man created or impacted habitats (e.g., wastewater treatment plants and agricultural soils). However, little is known on the plant-species association of AOBs, particularly in the nutrient-starved fynbos terrestrial biome. In this study, we evaluated the diversity of AOBs in the plant canopy of three South African fynbos-specific plant species, namely Leucadendron xanthoconus, Leucospermum truncatulum and Leucadendron microcephalum, through the construction of amoA-gene clone libraries. Our results clearly demonstrate that plant-species specific and monophyletic AOB clades are present in fynbos canopy soils.

Closing the empathy gap in college students' judgments of end-of-life tradeoffs.

When considering hypothetical end-of-life (EOL) scenarios involving 80-year-old intensive-care unit patients, young adults are more likely than older adults to judge that shorter lifespan would be a fair trade in exchange for a more pleasant death. This result has been interpreted in terms of an empathy gap, in which individuals fail to relate to the affective states of others. If so, the effect should be reduced when young adults consider scenarios involving patients similar to themselves. The present study examined college students' willingness to trade healthy lifespan for better death in EOL scenarios involving 80-year-old and 22-year-old cancer victims. Results indicated students under 30 were less likely to trade lifespan in the 22-year-old scenarios, and were less likely to trade lifespan in either set of scenarios when the 22-year-old scenarios were presented first. The findings are consistent with an empathy gap account of judgments concerning EOL care.

Age differences and schema effects in memory for crime information.

UNLABELLED: BACKGROUND/STUDY CONTEXT: This study investigated age-related differences in memory for crime information. Older adults have been found to rely more than young adults on schema- and stereotype-based processing in memory, and such age differences may have implications in the criminal justice system. Some prior research has examined schema-based processing among older adults in legal settings, but no studies have tested for schema effects on older adults' memory for specific details of a crime. METHODS: Older adults (N = 56, ages 65-93) and young adults (N = 52, ages 18-22) read a passage about a criminal suspect's "bad" or "good" childhood, and then read a crime report containing incriminating, exonerating, and neutral details with regard to the suspect. Participants were subsequently tested on recognition of accurate versus altered details from the crime report. Participants also rated the suspect"s guilt, and completed a battery of neuropsychological tests. Correct and false recognition rates were analyzed with ANOVA to compare means across age group, evidence type, and background type, and guilt ratings were analyzed with linear regression using neuropsychological scores as predictors. RESULTS: Among older adults, an interaction was found between evidence type (incriminating/exonerating) and suspect's background (good/bad childhood) in false recognition of altered details from the crime report, supporting the hypothesis that schema-based processing influenced older adult memory from crime information. Additionally, although guilt ratings were not related to the suspect's background for either age group, they were predicted by older adults' short-delay recall (ß = -.37), suggesting that cognitive decline may play a role in older adults' interpretations of evidence. CONCLUSION: The findings suggest reduced cognitive capacity in older adults increases schema-based processing in memory for crime information, and are consistent with research in other domains that has demonstrated greater schema effects in memory with aging. The results may have implications for criminal justice, and open up possibilities for further research on how young and older adults may differ in memory for specific types of crime information.

Synergistic effects of encoding strategy and context salience on associative memory in older adults.

Older adults' deficits in memory for context and memory for inter-item associations are often assumed to be related, yet typically are examined in separate experiments. The present study combined associative recognition and list discrimination into a single task with conditions that varied in terms of item, pair, and context information, and independently manipulated context salience and encoding strategy between subjects in order to examine their effects on memory for associative information in young and older adults. Older adults' memory for pairs was found to be less affected than that of young adults by manipulations of context and associative information, but the age difference in context effects on pair memory was influenced by an interaction of encoding strategy and context salience. The results provide novel evidence that older adults' deficits in associative memory involve interactions between context and inter-item associations.

How does context play a part in splitting words apart? Production and perception of word boundaries in casual speech.

Four experiments examined listeners' segmentation of ambiguous schwa-initial sequences (e.g., a long vs. along) in casual speech, where acoustic cues can be unclear, possibly increasing reliance on contextual information to resolve the ambiguity. In Experiment 1, acoustic analyses of talkers' productions showed that the one-word and two-word versions were produced almost identically, regardless of the preceding sentential context (biased or neutral). These tokens were then used in three listening experiments, whose results confirmed the lack of local acoustic cues for disambiguating the interpretation, and the dominance of sentential context in parsing. Findings speak to the H&H theory of speech production (Lindblom, 1990), demonstrate that context alone guides parsing when acoustic cues to word boundaries are absent, and demonstrate how knowledge of how talkers speak can contribute to an understanding of how words are segmented.

A standard set of American-English voiced stop-consonant stimuli from morphed natural speech.

Linear predictive coding (LPC) analysis was used to create morphed natural tokens of English voiced stop consonants ranging from /b/ to /d/ and /d/ to /g/ in four vowel contexts (/i/, /æ/, /a/, /u/). Both vowel-consonant-vowel (VCV) and consonant-vowel (CV) stimuli were created. A total of 320 natural-sounding acoustic speech stimuli were created, comprising 16 stimulus series. A behavioral experiment demonstrated that the stimuli varied perceptually from /b/ to /d/ to /g/, and provided useful reference data for the ambiguity of each token. Acoustic analyses indicated that the stimuli compared favorably to standard characteristics of naturally-produced consonants, and that the LPC morphing procedure successfully modulated multiple acoustic parameters associated with place of articulation. The entire set of stimuli is freely available on the Internet (http://www.psy.cmu.edu/~lholt/php/StephensHoltStimuli.php) for use in research applications.

Learning to use an artificial visual cue in speech identification.

Visual information from a speaker's face profoundly influences auditory perception of speech. However, relatively little is known about the extent to which visual influences may depend on experience, and extent to which new sources of visual speech information can be incorporated in speech perception. In the current study, participants were trained on completely novel visual cues for phonetic categories. Participants learned to accurately identify phonetic categories based on novel visual cues. These newly-learned visual cues influenced identification responses to auditory speech stimuli, but not to the same extent as visual cues from a speaker's face. The novel methods and results of the current study raise theoretical questions about the nature of information integration in speech perception, and open up possibilities for further research on learning in multimodal perception, which may have applications in improving speech comprehension among the hearing-impaired.

Formaldehyde gas inactivation of Bacillus anthracis, Bacillus subtilis, and Geobacillus stearothermophilus spores on indoor surface materials.

AIMS: To evaluate the decontamination of Bacillus anthracis, Bacillus subtilis, and Geobacillus stearothermophilus spores on indoor surface materials using formaldehyde gas. METHODS AND RESULTS: B. anthracis, B. subtilis, and G. stearothermophilus spores were dried on seven types of indoor surfaces and exposed to approx. 1100 ppm formaldehyde gas for 10 h. Formaldehyde exposure significantly decreased viable B. anthracis, B. subtilis, and G. stearothermophilus spores on all test materials. Significant differences were observed when comparing the reduction in viable spores of B. anthracis with B. subtilis (galvanized metal and painted wallboard paper) and G. stearothermophilus (industrial carpet and painted wallboard paper). Formaldehyde gas inactivated>or=50% of the biological indicators and spore strips (approx. 1x10(6) CFU) when analyzed after 1 and 7 days. CONCLUSIONS: Formaldehyde gas significantly reduced the number of viable spores on both porous and nonporous materials in which the two surrogates exhibited similar log reductions to that of B. anthracis on most test materials. SIGNIFICANCE AND IMPACT OF THE STUDY: These results provide new comparative information for the decontamination of B. anthracis spores with surrogates on indoor surfaces using formaldehyde gas.

A critical evaluation of visually moderated phonetic context effects.

Fowler, Brown, and Mann (2000) have reported a visually moderated phonetic context effect in which a video disambiguates an acoustically ambiguous precursor syllable, which, in turn, influences perception of a subsequent syllable. In the present experiments, we explored this finding and the claims that stem from it. Experiment 1 failed to replicate Fowler et al. with novel materials modeled after the original study, but Experiment 2 successfully replicated the effect, using Fowler et al.'s stimulus materials. This discrepancy was investigated in Experiments 3 and 4, which demonstrate that variation in visual information concurrent with the test syllable is sufficient to account for the original results. Fowler et al.'s visually moderated phonetic context effect appears to have been a demonstration of audiovisual interaction between concurrent stimuli, and not an effect whereby preceding visual information elicits changes in the perception of subsequent speech sounds.