Is speech perception modular or interactive?

Norris et al. recently reported experimental evidence that listeners learn phoneme categories in response to lexical feedback. To reconcile these findings with their modular account of speech perception, the authors argue that top-down feedback can be used to support phoneme learning, but not to influence on-line phonemic processing. We suggest that these findings have broader implications than the authors assume, and we discuss potential challenges for integrating a modular theory with top-down learning.     

Recruitment of first-generation Latinos in a rural community: the essential nature of personal contact

The purpose of this article is to report on the success of various recruitment activities for a behavioral observation study with Spanish-speaking Latino families in a rural community in the western United States. Recruitment activities are pivotal to research to research because the enormous impact to the quality of the sample and, thus, the quality of the answers to the questions posed by the research. Recruitment can be especially challenging for researchers working with ethnic minorities due to a historical legacy of mistreatment by researchers that has led to healthy reticence to participate in research investigations. The present research presented unique challenges in that the data collection (1) took place in a rural community, (2) sought participation of a recent immigrant population, and (3) required videotaping. Data were collected from 50 families in a western rural community. After multiple recruitment strategies were used, the research team learned that word of mouth and use of existing community resources were the most powerful recruitment strategies. However, participant reports suggest that the other recruitment strategies helped familiarize participants with the study and potentially strengthened the influence of word of mouth referrals. Important differences were found between the easy-to-recruit and the hard-to-recruit samples within this study that support engagement in multiple recruitment strategies.     

The Bristol norms for age of acquisition, imageability, and familiarity

Ratings of age of acquisition (AoA), imageability, and familiarity were collected for 1,526 words. The methodology made use of a modular approach, in which the full sample of words was divided into five separate blocks. Within each block, each word was rated on each of the three variables by 20 participants (undergraduate students from the University of Bristol). Analyses comparing these ratings to existing norm databases demonstrated that this methodology resulted in high reliability (assessed by Cronbach’s α) and validity. The ratings were also transformed to be compatible with the Gilhooly and Logie (1980) norms. This transformation resulted in a set of norms for 3,394 words, which is by far the largest database of ratings for AoA, imageability, and familiarity to date. The resulting database should be useful for researchers interested in manipulating or controlling these factors in word recognition, neuropsychological, or memory studies. These norms can be downloaded from language.psy.bris .ac.uk/bristol_norms.html.     

On the complexities of measuring naming

The aims of this study were to investigate the adequacy of electronic voice keys for the purpose of measuring naming latency and to test the assumption that voice key error can be controlled by matching conditions on initial phoneme. Three types of naming latency measurements (hand-coding and 2 types of voice keys) were used to investigate effects of onset complexity (e.g., sat vs. spat) on reading aloud (J. R. Frederiksen & J. F. Kroll, 1976; A. H. Kawamoto & C. T. Kello, 1999). The 3 measurement techniques produced the 3 logically possible results: a significant complexity advantage, a significant complexity disadvantage, and a null effect. Analyses of the performance of each voice key are carried out, and implications for studies of naming latency are discussed.     

Second-order olfactory-mediated fear-potentiated startle

Recently, we reported that discrete (4-sec) olfactory cues paired with footshock serve as effective conditioned stimuli (CSs) for potentiating the acoustic startle response in rats using the fear-potentiated startle paradigm. Because odors are such salient cues for the rat, and because of the robust olfactory conditioning observed previously, the current studies investigated second-order fear conditioning using olfactory and visual cues. In Experiments 1 and 2, we used a small number of first-order and second-order training trials on separate days to investigate second-order fear-potentiated startle. Significant potentiated startle was observed in animals receiving Paired/Paired training in both studies, but surprisingly, control animals in the Unpaired/Paired group (Exp. 1) also showed significant potentiated startle to a light S2 at testing. These findings are addressed in the Discussion. Overall, the results of both experiments suggest that olfactory cues serve as efficient S1 and S2 stimuli in second-order fear-potentiated startle paradigms when only a small number of first and second-order training trials are presented.     

Glutamate receptor antagonist infusions into the basolateral and medial amygdala reveal differential contributions to olfactory vs. context fear conditioning and expression

The basolateral amygdala's involvement in fear acquisition and expression to visual and auditory stimuli is well known. The involvement of the basolateral and other amygdala areas in fear acquisition and expression to stimuli of other modalities is less certain. We evaluated the contribution of the basolateral and medial amygdala to olfactory and to context fear and fear conditioning by infusing into these areas the NMDA receptor antagonist AP5, the AMPA/kainate receptor antagonist NBQX, or vehicle prior to either odor-shock pairings or fear-potentiated startle testing. Pre-training AP5 infusions into the basolateral amygdala disrupted fear conditioning to the odor but not the context conditioned stimulus (CS). Pre-test NBQX infusions disrupted fear-potentiated startle to the odor but not context CS. Neither compound blocked fear conditioning when infused into the medial amygdala prior to training, but pre-test NBQX infusions did block fear-potentiated startle. The results confirm and extend recent findings suggesting a role for the basolateral amygdala in olfactory fear and fear conditioning, reveal an unexpected dissociation of the basolateral amygdala's involvement in discrete cue versus context fear and fear conditioning, and implicate for the first time the medial amygdala in fear-potentiated startle.     

Differential effects of estrogen on hippocampal- and striatal-dependent learning

Estrogen's role in learning and memory may be to predispose animals to use specific cognitive strategies (Korol & Kolo, 2002). Specifically, estrogen may facilitate hippocampal-dependent learning, while at the same time attenuate striatal-dependent learning. As a stringent test of this hypothesis, place or response learning on an eight-arm radial maze was compared between ovariectomized (OVX) female Long-Evans rats and rats with chronic estrogen replacement (OVX+E; 5mg 17-beta estradiol 60-day release tablet). Reference and working memory errors were monitored separately for both place and response learning tasks. OVX+E rats learned the place task significantly faster than the response task, and faster than OVX rats. OVX rats required fewer days to reach criterion on the response task than OVX+E rats. Estrogen selectively enhanced reference memory performance, but only during place learning. The specific pattern of estrogen effects on learning suggests that future studies include verification of cognitive strategies used by animals.