Neural correlates of the production effect: An fMRI study

Effectiveness of production and drawing as encoding techniques on recall using mixed- and pure-list designs

We compared the benefit of production and drawing on recall of concrete and abstract words, using mixed- and pure-list designs. We varied stimulus and list types to examine whether the memory benefit from these strategies was sustained across these manipulations. For all experiments, the memory retrieval task was free recall. In Experiment 1, participants studied concrete and abstract words sequentially, with prompts to either silently-read, read aloud, write, or draw each target (intermixed). Reading aloud, writing, and drawing improved recall compared to silent reading, with drawing leading to the largest boost. Performance, however, was at floor in all but the drawing condition. In Experiment 2, the number of targets was reduced, and each strategy (between-subjects) was compared to silent-reading. We eliminated floor effects and replicated results from Experiment 1. In Experiment 3, we manipulated strategy in a pure-list-design. The drawing benefit was maintained while that from production was eliminated. In all experiments, recall was higher for concrete than abstract words that were drawn; no such effect was found for words produced. Results suggest that drawing facilitates memory by enhancing semantic elaboration, whereas the production benefit is largely perceptually based. Importantly, the memory benefit conferred by drawing at encoding, unlike production, cannot be explained by a distinctiveness account as it was relatively unaffected by study design.

Generation (not production) improves the fidelity of visual representations in picture naming

The production effect refers to the finding that participants better remember items read aloud than items read silently. This pattern has been attributed to aloud items being relatively more distinctive in memory than silent items, owing to the integration of additional sensorimotor features within the encoding episode that are thought to facilitate performance at test. Other theorists have instead argued that producing an item encourages additional forms of processing not limited to production itself. We tested this hypothesis using a modified production task where participants named monochromatic line drawings aloud or silently either by generating the names themselves (no label condition) or reading a provided label (label condition). During a later test, participants were presented with each line drawing a second time and required to reproduce the original color and location using a continuous slider. Production was found to improve memory for visual features, but only when participants were required to generate the label themselves. Our findings support the notion that picture naming improves memory for visual features; however, this benefit appears to be driven by factors related to response generation rather than production itself.

Enhancing speech perception in noise through articulation

Considerable debate exists about the interplay between auditory and motor speech systems. Some argue for common neural mechanisms, whereas others assert that there are few shared resources. In four experiments, we tested the hypothesis that priming the speech motor system by repeating syllable pairs aloud improves subsequent syllable discrimination in noise compared with a priming discrimination task involving same-different judgments via button presses. Our results consistently showed that participants who engaged in syllable repetition performed better in syllable discrimination in noise than those who engaged in the priming discrimination task. This gain in accuracy was observed for primed and new syllable pairs, highlighting increased sensitivity to phonological details. The benefits were comparable whether the priming tasks involved auditory or visual presentation. Inserting a 1-h delay between the priming tasks and the syllable-in-noise task, the benefits persisted but were confined to primed syllable pairs. Finally, we demonstrated the effectiveness of this approach in older adults. Our findings substantiate the existence of a speech production-perception relationship. They also have clinical relevance as they raise the possibility of production-based interventions to improve speech perception ability. This would be particularly relevant for older adults who often encounter difficulties in perceiving speech in noise.

Age differences in effectiveness of encoding techniques on memory

We compared the effectiveness of different encoding techniques across the adult age range. Three hundred participants: 100 younger, 100 middle-aged, and 100 older adults, were asked to encode a set of visually presented concrete and abstract words. Participants were shown target words one at a time, along with prompts (randomly and intermixed, within-subject) to either silently read, read aloud, write, or draw a picture of the target, for a duration of 10-seconds each. On a later free recall test, participants were given 2-minutes to type all the words they could remember from the encoding phase. Across age groups, we showed that drawing, writing, and reading aloud as encoding techniques yielded better memory than silently reading words, with drawing leading to the largest boost. While memory performance did decrease as age increased, it interacted with the encoding technique. Of note, there were no differences in memory performance in middle-aged compared to young adults. Importantly, age differences in memory emerged only when drawing was used as the encoding strategy, in line with previously reported age-related deficits in generating imagery, or integrating it with motoric processes. Despite this, concrete relative to abstract words that were drawn or written during encoding were better retained, regardless of age, suggesting these techniques facilitate formation of age-invariant visuo-spatial representations. Our findings suggest that whether age differences in memory emerge depends on the strategy used at encoding, and the type of information being encoded.

Production benefits on encoding are modulated by language experience: Less experience may help

Several lines of research have shown that performing movements while learning new information aids later retention of that information, compared to learning by perception alone. For instance, articulated words are more accurately remembered than words that are silently read (the production effect). A candidate mechanism for this movement-enhanced encoding, sensorimotor prediction, assumes that acquired sensorimotor associations enable movements to prime associated percepts and hence improve encoding. Yet it is still unknown how the extent of prior sensorimotor experience influences the benefits of movement on encoding. The current study addressed this question by examining whether the production effect is modified by prior language experience. Does the production effect reduce or persist in a second language (L2) compared to a first language (L1)? Two groups of unbalanced bilinguals, German (L1) - English (L2) bilinguals (Experiment 1) and English (L1) - German (L2) bilinguals (Experiment 2), learned lists of German and English words by reading the words silently or reading the words aloud, and they subsequently performed recognition tests. Both groups showed a pronounced production effect (higher recognition accuracy for spoken compared to silently read words) in the first and second languages. Surprisingly, the production effect was greater in the second languages compared to the first languages, across both bilingual groups. We discuss interpretations based on increased phonological encoding, increased effort or attention, or both, when reading aloud in a second language.

Which Encoding Techniques Facilitate Comprehension?

Previous work suggests that similar cognitive processes contribute to memory and comprehension. This is unsurprising as both begin with a common process: encoding. Despite this, the investigation of techniques that benefit memory and comprehension has proceeded separately. In the current study, we compared the robust memory techniques of production and drawing to a similarly effective comprehension strategy known as paraphrasing. Depending on the group, participants were asked to either engage in one of the encoding types (read aloud, draw, or paraphrase) or to silently read 20 term-definition pairs (randomly intermixed and counterbalanced). The encoding techniques of drawing and paraphrasing resulted in better performance on a multiple-choice test of concept comprehension, relative to silently reading. By contrast, reading aloud at encoding did not lead to any benefit relative to silently reading. The results suggest that techniques that invoke transformation of the to-be-remembered text into another format, be it into a picture (drawing) or personally relevant summary (paraphrasing), are particularly effective at improving comprehension. By contrast, encoding techniques that mainly provide a perceptual repetition (production and silent reading) are less effective.

The stranding of the ideography: A nonnegligible role of the spoken language

Morin suggested that one of the reasons for the difficulty in standardizing graphic codes is that the production of spoken language reduces the need for graphic codes. Here we try to extend their claims from a psychological perspective, which allows us to conclude that the puzzle of ideography is perhaps related to human psychological traits and psychological evolution.

Neural representation of a one-week delay in remembering information after production and self-generated elaboration encoding strategy

Many studies have confirmed the memory enhancement effect of production, generation and elaboration which can be effective after only one encoding. It is also known that greater memory enhancement effects can be obtained by combining multiple memory strategies during encoding. This study aimed to investigate whether the combination of production and self-generated elaboration enhances memory performance compared with production or generation alone. A total of 23 undergraduate and graduate students participated in this study. In the functional magnetic resonance imaging analysis, we explored the neural representation of remembering information after production and self-generated elaboration strategy. We set four encoding strategy conditions: (1) Read Silent (read without production), (2) Read Aloud (only production), (3) Add Silent (self-generated elaboration without production), (4) Add Aloud (production and self-generated elaboration). The retrieval performance and brain activity while retrieving the learned sentences after a one-week delay were examined. The behavioral results showed that the highest memory performance was for sentences encoded in Add Aloud. The interaction between production and self-generated elaboration was statistically significant. These results suggest that the memory enhancement effect of combining production and self-generated elaboration is not a simple addition nor synergistic facilitation effect. The imaging results showed that the following areas were related to the retrieval of the target encoded in the add aloud condition: the area related to integration of internal and external information (precuneus), area related to information rich stimuli (lateral occipital lobe), area related to self-involvement and inference of others' feelings (MPFC), area related to seen imagery (retrosplenial region) and area related to adjustment of movement (cerebellum). These results suggest that with an encoding strategy that combines production and self-generated elaboration, integrated auditory input of vocalizations and generated images, visual images of the scene, self-relevance, inference of other's feeling, movement by moving mouth are stored with the target and enhanced memory performance of AA.

EEG-based univariate and multivariate analyses reveal that multiple processes contribute to the production effect in recognition

The production effect (PE) is the finding that reading words aloud rather than silently during study leads to improved memory. We used electroencephalography (EEG) techniques to detect the contributions of recollection, familiarity, and attentional processes to the PE in recognition memory, using Chinese stimuli. During the study phase, participants encoded each list item aloud, silently, or by performing a non-unique aloud (control) task. During the test phase, they made remember/know/new recognition judgments. We recorded EEG data in both phases. The behavioral results replicated the typical pattern with English stimuli: Recognition was better in the aloud condition than in the silent (and control) condition, and this PE was due to enhanced recollection and familiarity. At study, the amplitude of the P3b ERP component was greater in the aloud than in the silent/control conditions, suggesting that reading aloud increases attention or preparatory processing during the intention phase. At test, the recollection-based LPC old/new effect was largest in the aloud condition; however, the familiarity-based FN400 old/new effect was equivalent between the aloud condition and the silent/control conditions. Only the LPC effect correlated with the behavioral effect. Moreover, multivariate pattern analysis (MVPA) showed that accurate classification of items as 'aloud' versus 'new' mainly occurred in the later period of the recognition response, consistent with the LPC old/new effect. Our findings suggest that the within-subject PE in recognition memory reflects enhanced attention and distinctiveness, rather than increased memory strength. More broadly, our findings suggest that encoding strategies such as production enhance recollection more than familiarity.

Production can enhance semantic encoding: Evidence from forced-choice recognition with homophone versus synonym lures

The production effect-better memory for words read aloud rather than silently-has been attributed to responses at test being guided by memory for the act of production. In Experiment 1, we evaluated this distinctiveness account by comparing production effects in forced-choice recognition when lures were either homophones of the targets (toad or towed?) or unrelated words (toad or seam?). If the production effect at test was driven solely by memory for the productive act (e.g., articulation, auditory processing), then the effect should be reduced with homophone lures. Contrary to that prediction, the production effect did not differ credibly between homophone-lure and unrelated-lure groups. Experiment 1 led us to hypothesize that production may also boost semantic encoding, and that participants use memory of semantic encoding to guide their forced-choice responses. Consistent with these hypotheses, using synonym lures to interfere with semantic-based decisions (poison or venom?) reduced the production effect relative to using unrelated lures (poison or ethics?) in Experiment 2. Our findings suggest that enhanced conceptual encoding may be another useful product of production.