Robert E. Till

Time course of priming for associate and inference words in a discourse context

The construction of word meanings in a discourse context was conceptualized as a process of sense activation, sense selection, and sense elaboration. In three experiments, subjects read texts presented by a rapid serial visual procedure and performed a lexical decision on visually presented targets that followed ambiguous prime words. When the target was a word, it was either an associate of the prime word, a probable inference suggested by the discourse, or an unrelated word. For associates, lexical decisions that related to either the appropriate or the inappropriate sense of the ambiguous word were generally facilitated at short (200-400 msec) prime-target stimulus onset asynchronies (SOAs). At longer SOAs, responses were faster to appropriate than to inappropriate associates. For the thematic inferences, there was no difference between these (appropriate) inferences and (inappropriate) control words at short SOAs. At long SOAs (1,000 and 1,500 msec), however, inference words were facilitated. The results are interpreted as consistent with a model of lexical processing in which sense activation functions independently of context. Discourse context effects, whether on sense selection (suppression of inappropriate associates) or on sense elaboration (creation of inferences), are seen as postlexical.

Vasopressin analog (DDAVP) improves memory in human males

One specific analog of arginine vasopressin, 1-desamine-8-D-arginine vasopressin (DDAVP), has been shown to improve learning and memory in humans. Healthy young male adult subjects treated with DDAVP demonstrated better memory for implicational sentences than did control subjects. The same treatment had no influence on women given the same memory task. These results suggest that DDAVP may have a sexually dimorphic effect on learning and memory.

Effects of Cuing on Short-Term Retention of Order Information

In two experiments, subjects recalled one of two letter sequences following a digit-filled retention interval. Recall performance was increased by precues informing subjects which letter sequence would be tested, and the cuing advantage remained throughout 60-digit retention intervals. No improvement was found, however, for cues occurring after the letters but before the digits. The cuing effects were attributed to encoding, not rehearsal, processes and were explained by a version of the Estes perturbation model, which included a long-term storage component and a fixed perturbation probability.

Sentence memory affected by vasopressin analog (DDAVP) in cross-over experiment

DDAVP has been shown to facilitate memory, especially retrieval, in humans. Healthy young male adult subjects received DDAVP (60 micrograms) in a cross-over design with a one-week interval between sessions. Results indicated that DDAVP improved immediate memory during the first but not the second testing session, particularly for low-verbal subjects. Treatment with DDAVP also facilitated delayed (one-week) recall in the opposite group, a cross-over interaction that suggests a retrieval locus for the DDAVP effect. Furthermore, since DDAVP improved immediate memory more for low-verbal subjects and delayed memory more for high-verbal subjects, it appears that individual difference factors will be important in understanding the effects of vasopressin on memory.

Dose-dependent effects of DDAVP on memory in healthy young adult males: A preliminary study

Although several studies have demonstrated the efficacy of the vasopressin analog DDAVP in enhancing human memory, no previous study has reported the dose-response relationship of DDAVP to memory in healthy young adults. The present study was undertaken to explore the dose-response curve for DDAVP on recall of implicational sentences. Five doses of DDAVP (0, 5, 15, 30, and 60 micrograms) were administered intranasally to healthy young adult male volunteers. Results demonstrated a facilitation in cued recall after treatment with the 60-micrograms dose and a general impairment in recall after treatment with the 15-micrograms dose. These effects were independent of subjects weight, vocabulary ability, and concentration of salivary cortisol.

Age differences in picture memory with resemblance and discrimination tasks.

Previous research on recognition memory has examined age-related effects on knowledge of the difference between lures and input items (e.g., false alarm rate), but has not examined age-related effects on knowledge of the resemblance between lures and input items. In the present experiment, subjects in two age groups (means = 19.3 years and 63.8 years) saw a list of scenic pictures, followed by a recognition test containing same-photo items, each a copy of an input picture, same-scene items, each from the same original scene as an input picture, and different-scene items. The task was to categorize each test picture as same-photo, same-scene or different-scene. There were no reliable age differences on standard recognition measures of hits and false alarms. However, younger subjects were better than older subjects at detecting the resemblance between same-scene items and input items, although this age difference was less apparent when the initial encoding provided experience with resemblance detection. The results have implications regarding age effects in picture memory and in recognition memory generally.

Is there really very rapid forgetting from primary memory? The role of expectancy and item importance in short-term recall.

In two experiments, subjects recalled one of two letter segments following a digit-filled retention interval. In Experiment 1, recall expectancy was manipulated by using precues that correctly informed or misinformed subjects concerning which letter segment wou;d be tested for recall. In Experiment 2, item importance was varied by precuing one segment as important but requiring that the uncued segment be recalled first. Recall performance was very low under conditions of low expectancy and low segment importance, but the slopes of the retention-functions did not demonstrate more rapid forgetting than under standard -conditions. The previous observations of very rapid forgetting from primary memory may be a function of an elevated initial recall level in the earlier studies. Our retention functions were compared with predictions of the Estes perturbation model. The findings suggested that when secondary memory processes were reduced, forgetting order information from primary memory occurred at the same rate as that estimated on the basis of previous studies using the standard distractor task.

Pronoun reference and aging

We investigated whether an age‐related deficit occurs for pronoun‐reference resolution. Young (ages 19–31) and older (ages 60–74) adults read stories varying in length and selected the antecedent noun for sentences that contained information that was expected, neutral, or unexpected with respect to prior knowledge. The qualitative factor (Expectedness) produced an age‐related effect for accuracy of noun choice but the quantitative factor (Memory Load or the distance between noun and pronoun) was equivalent for all subjects. Additionally, older adults took longer to read the text than the young, although there was no interaction with age. It is argued that expectedness of information may be more relevant for pronoun‐reference processing rather than memory load alone in older adult readers.

Encoding-retrieval interactions in memory for implicational sentences

In two experiments, subjects listened to a list of implicational sentences and performed either a comprehension or a memorization task. They were subsequently given a test of free recall or cued recall (with implications as cues). Performance in the comprehension/cued-recall condition was consistently better than that in the dissimilar-encoding/retrieval conditions (memorization/cued recall and comprehension/free recall), supporting the hypothesis that encoding/retrieval similarity facilitates recall. In contrast, performance in the memorization/free-recall condition was not consistently better than in the dissimilar-encoding/retrieval conditions. Thus, the advantage of encoding/retrieval similarity for recall was clear only in the case of distinctive encoding (specific comprehension responses) and distinctive retrieval cues (implications as cues). The results show the relevance of distinctiveness and encoding/retrieval compatibility for memory of meaningful material.