Subcortical aphasia with deep dyslexia: A case study of a Japanese patient

The reading performance of a Japanese Broca-type aphasic patient on a single-word reading test was investigated. The result indicated that the subject fits the symptom complex of deep dyslexia in more than one aspect. Unique characteristics of this subject included (1) the isolated subcortical site of the lesion, which apparently produced deep dyslexia, and (2) double dissociations between kanji and kana processing and between oral reading and reading comprehension. The performance of this subject was compared with that of another Japanese deep dyslexic subject in S. Sasanuma (1980, In M. Coltheart, K. Patterson, & J. C. Marshall (Eds.), Deep dyslexia, London: Routledge & Kegan Paul). A theoretical implication was attempted based on a dual coding process scheme by S. Sasanuma and O. Fujimura (1978, Cortex, 7, 1-18).     

Levels of selection and capacity limits

Subjects performed a visual target-detection task in eight experiments. We examined the effects of word relevancy (word in relevant or irrelevant location) and display load (1-4 words) on physical, semantic, and controlled processing of nontargets. Interwoven with the detection task was a test-word identification task that was used to measure priming potency of nontargets. Physical and semantic levels of processing were measured in terms of identity and semantic priming, respectively. Nontarget primes were repeated as test words in identity priming. Nontarget primes were semantic associates of test words in semantic priming. Controlled processing of nontargets was measured in terms of recognition memory on a subsequent test. All measures increased with word relevancy and decreased with display load. The priming effects remained intact even when word presentation was speeded up and controlled processing was sharply curtailed. The data indicate that all levels of processing are selective and capacity limited.     

When selective adaptation and contrast effects are distinct: a reply to Diehl, Kluender, and Parker

Two alternative conceptualizations of selective adaptation with speech have recently received attention. The adaptation level theory (AL) outlined by Diehl (1981) and a two-stage model outlined by Sawusch and Jusczyk (1981) can both account for much of the adaptation and paired-comparison data. Recently, Diehl, Kluender, and Parker (1985) proposed that all adaptation and contrast data can be accounted for by AL theory. They reported the results of a study that showed evidence of streaming in selective adaptation and claimed that their results provide a counterdemonstration to recent studies that have argued against the AL approach. In the present article, an outline of how the Diehl et al. results can be accounted for by both the two-stage model and AL theory is presented. In addition, a new set of results comparing adaptation and paired-comparison procedures is presented. These results are precisely as predicted by the two-stage model, but they can not be handled by AL theory.     

A secondary-task analysis of a word familiarity effect

In three experiments we examined aspects of the word inferiority effect and word frequency disadvantage for letter detection. In Experiment 1 we tested a prediction derived from a hypothesis based solely on attentional factors. Adult subjects performed one of two secondary detection tasks while reading for comprehension. The inferiority effects were obtained only when the secondary task was letter detection, not when nonletter targets were used in the secondary task. This finding is inconsistent with the attentional hypothesis, but is consistent with the unitization hypothesis of Healy and Drewnowski (1983). In Experiments 2 and 3 we found that manipulation of the need to read for comprehension had little influence on the letter-detection inferiority effects, but a strong influence on the effects involving the detection of nonletter targets. These results are discussed in terms of their implications concerning processing system flexibility.     

Distributed memory and the representation of general and specific information

We describe a distributed model of information processing and memory and apply it to the representation of general and specific information. The model consists of a large number of simple processing elements which send excitatory and inhibitory signals to each other via modifiable connections. Information processing is thought of as the process whereby patterns of activation are formed over the units in the model through their excitatory and inhibitory interactions. The memory trace of a processing event is the change or increment to the strengths of the interconnections that results from the processing event. The traces of separate events are superimposed on each other in the values of the connection strengths that result from the entire set of traces stored in the memory. The model is applied to a number of findings related to the question of whether we store abstract representations or an enumeration of specific experiences in memory. The model simulates the results of a number of important experiments which have been taken as evidence for the enumeration of specific experiences. At the same time, it shows how the functional equivalent of abstract representations--prototypes, logogens, and even rules--can emerge from the superposition of traces of specific experiences, when the conditions are right for this to happen. In essence, the model captures the structure present in a set of input patterns; thus, it behaves as though it had learned prototypes or rules, to the extent that the structure of the environment it has learned about can be captured by describing it in terms of these abstractions.     

Reflex modification in the rat: the inhibitory effects of intensity and frequency changes in steady tones

In laboratory rats (as in humans) a low-intensity tone that precedes a high-intensity burst of noise by approximately 100 ms can reduce the amplitude of the startle reaction elicited by the burst of noise. A series of four experiments with rats investigated the relation between the inhibitory effects of tonal frequency change and the length of the silent period (gap) preceding it. The major findings were the following: (a) A gap in an otherwise continuous pure tone inhibited startle when the gap occurred approximately 100 ms prior to the noise burst. (b) Although an increase in gap duration increased the inhibition afforded by the gap, the maximum inhibition was yielded by gaps of 100 ms and greater; this maximum was equivalent to the inhibition yielded by the presentation of a postgap tone alone. (c) A shift in tonal frequency across a 10-ms gap yielded more inhibition than did the same gap with no frequency shift; again the shift yielded equivalent inhibition to the presentation of the postgap tone alone. (d) An increase in the frequency shift increased inhibition when the shift occurred across a 10-ms gap, but not when the shift occurred across a 100-ms gap.     

The word-superiority effect under conditions that approximate reading

Observers detected a briefly flashed target letter embedded in word, pronounceable nonword, and unpronounceable nonword contexts. The word context facilitated perception under both holistic and analytical processing strategies; the facilitative effect was enhanced when processing was analytical.