Gillian Cohen

Language comprehension in old age

Abstract Three experiments examined the effects of aging on comprehension of spoken language. Integrative and constructive aspects of comprehension showed much more marked age-related deficits than registration of surface meaning. Experiment 1 showed that old subjects had difficulty in making inferences based on presented facts. Experiment 2 revealed a similar deficit in old peoples ability to detect anomalies in newly presented information by reference to prior everyday knowledge. And Experiment 3, which tested story recall, showed that old subjects were less well able to extract and retain gist information than younger subjects. These difficulties are interpreted as reflecting a limitation in processing capacity such that the demands of concurrently registering surface meaning and simultaneously carrying out integrative and constructive processes exceed capacity in old age.

Hemispheric differences in a letter classification task

The experiment examined hemispheric differences in same-different judgments for unilaterally presented letter pairs which could be classified as “same” on the basis of name identity (NI, e.g., Aa) or physical identity (PI, e.g., AA). Two groups of Ss were tested, a right-handed group and a predominantly left-handed group. The experiment employed a reaction time measure, and fixed the duration of brief exposures to yield an overall performance level of 90% correct. Analysis of the results focused on the difference between RTs for the NI matches and for the PI matches in each hemisphere. The method allowed differences in cognitive processing to be assessed while sensory and response factors were minimized. The right-handed group all showed a smaller mean NI-PI difference in the left hemisphere (84 msec) than in the right hemisphere (181 msec). The left-handed group showed smaller and less consistent differences, but the group as a whole had a reversed asymmetry, with a mean NI-PI difference of 128 msee in the left hemisphere and 90 msec in the right hemisphere.

Inferential reasoning in old age.

Abstract Two experiments examined the effects of aging on the kind of inferential reasoning required in comprehending discourse. In Experiment 1 old subjects made more errors than young subjects in solving logical problems framed in everyday language. Unlike the young subjects they had more difficulty when the problems were spoken than when they were written. Experiment 2 revealed that old subjects are inefficient at extracting implicit information during reading; they fail to generate bridging inferences to supply missing information, so that comprehension is restricted to explicitly stated information. The results show that verbal reasoning ability is impaired in old age and that this affects language comprehension in both listening and reading although the deficit is more marked in listening.

Hemisphere differences in an auditory Stroop test

In an auditory Stroop test, right-handed subjects were required to judge the pitch of the following stimuli: two pure tones, one at a high frequency and one at a low frequency; two congruent words, “high,” sung at the high frequency, and “low,” sung at the low frequency; and two noncongruent words, “high” at low frequency and “low” at high frequency. A sequence of these stimuli was presented monaurally first to one ear, and then to the other. The Stroop effect (the difference between mean RT to congruent words, and mean RT to noncongruent words) was larger for right ear (left hemisphere) presentation. The same experiment was repeated dichotically with a competing message presented to the opposite ear. Again, the Stroop effect was larger for the right ear, and the ear differences were slightly more marked. The result is interpreted as reflecting hemispheric specialization for linguistic and nonlinguistic processing and a model of Stroop conflict in which response competition varies with the relative availability of the conflicting response.

How are pictures registered in memory

Three experiments tested the hypothesis that pictorial memory is much less dependent on rehearsal than is verbal memory. Experiment I examined incidental learning since this is assumed to reflect learning with little or no rehearsal. Following a classification task, intentional and incidental learning for pictures and for words was compared. The superiority of pictorial memory was especially marked in incidental learning. Experiment II showed that this result was not due to differences in the amount of processing required to classify pictures and words. RTs to classify words and pictures did not differ, and incidental learning was again superior for pictures. In Experiment III rehearsal opportunity was restricted by a concurrent task during presentation of word and picture lists, and the decrement was very much greater for word learning than for picture learning. It was concluded that manipulation of rehearsal opportunity has relatively little effect on pictorial memory.

Memory for Discourse in Old Age.

Memory for discourse in old age was examined by comparing the performance of matched groups of old and young subjects in a text recognition task. Subjects listened to a spoken text, and were then required to detect changes in a written version of the text. The delay and amount of material intervening before the relevant portion of the text was re‐presented, were manipulated. The results showed that memory for discourse is generally impaired by aging. The effects of delay showed age differences in retention. Memory for wording (ability to detect non‐semantic changes) declined rapidly in both age groups. While the young showed good retention of meaning (detection of semantic changes was 98 percent correct at 10 seconds delay and 88 percent correct at 40 seconds), semantic information was poorly retained by the old group (detection of semantic Changes fell from 83 percent at 10 seconds to 33 percent at 40 seconds). Comparison of performace across different types of semantic change showed that the old, but no...

Components of the laterality effect in letter recognition: Asymmetries in iconic storage

A partial report procedure and a backward masking paradigm were employed to explore lateral asymmetries in components of letter recognition. Stimulus displays were displaced off-centre into the left visual field (LVF) or the right visual field (RVF). Visual field differences in the effect of a delayed backward mask indicated an RVF superiority in the rate of read-out or encoding. Comparison of masked and unmasked full report also yielded estimates of iconic persistence. The persistence of these peripheral displays was surprisingly brief, although it was significantly longer in the LVF (57 ms) than in the RVF (34 ms). Precueing by colour and by location produced a larger partial report advantage in the RVF, reflecting a superiority in selective sampling. With postcueing no partial report effect was obtained at any delay, and this failure was attributed to the briefness of the iconic persistence.

A comparison of semantic. acoustic and visual criteria for matching of word pairs

Ss judged the some pairs of words “same” or “different” under semantic, acoustic and visualcriteria. RTs were compared for each criterion, and the effects of different kinds of confusabittty, such as acoustic similarity in the semantic matching task, or semantic similarity in the acoustic matching task, were also studied.

Search times for combinations of visual, phonemic, and semantic targets in reading prose

Subjects read passages of prose, canceling targets that were visual (letters), acoustic (phonemes), or semantic (words of a specified category). Each of the targets occurred singly and in all possible double and triple combinations. Comparison of the search times reveals that semantic processing adds little or no extra time when combined with acoustic or with visual and acoustic searches, i.e., it occurs in parallel. Other combinations of processing yield search times that are slightly faster than a serial model would predict and are best interpreted as reflecting an overlapping sequence of operations.

Some evidence for parallel comparisons in a letter recognition task

Subjects were asked to judge successively presented letter trigrams “same” or “different.” The different stimuli were divided into four groups; not confusable (NC), acoustically confusable (AC), visually confusable (VC), and both visually and acoustically confusable (VC & AC). Reaction times (RT) were lengthened only by the double confusability. It is argued that comparisons are normally made in both channels, so that confusability in a single channel has no effect since the alternative channel is unimpaired. RTs are only increased when both channels are slowed down. A further experiment confirms this interpretation. When the situation is manipulated so that only the visual channel is employed, the VC group shows the same increase as the VC & AC group.