Channel capacity and processing of modality specific information

The synthesis model, designed to explain effects of modality specific information on retention, is presented and tested. The model encompasses qualitative and quantitative components. The qualitative characteristics reflect the physiological properties of the auditory and visual channels. Three parameters are assumed to affect the quantitative efficiency of the channels. Each channel is assumed to have a certain capacity, and processing of information in the channels is determined by situational demands. Furthermore, processing in a channel is regarded as superficial. Increased allocation of processing to the superficial level was manipulated by the use of modality specific distractors and conditions of ‘supracapacity load’. Transformation of information from the visual to the auditory channel was controlled by the use of one mixed-mode and one single-mode experiment. Thirty subjects participated in the mixed-mode experiment and 60 in the single-mode experiment. Both experiments employed an identical distraction task, intervening presentation and free recall of the to-be-remembered items. The results confirmed the predictions of (a) modality specific distraction, (b) supracapacity performance decrement, (c) a larger distraction effect for the auditory channel and (d) transformation effects in the single-mode experiment.     

A watched pot sometimes boils: a study of duration experience

The ‘watched pot’ phenomenon — the lengthening of duration experience when one is attentively and perhaps impatiently waiting for some event to occur — was studied in three experiments. In them, each observer attended for a duration of 270 sec to a liquid-containing beaker on an electrical burner. Observers who were told that the experiment concerned time perception (prospective paradigm) reproduced the duration as longer than those told that it concerned visual perception (retrospective paradigm). In the prospective paradigm, reproductions were longer if the liquid did not boil than if it did, and an interruption (task-unrelated questioning) shortened reproductions if the liquid did not boil but had no effect if it did. In the retrospective paradigm, if there was boiling or questioning or both, reproductions were longer than if there was neither. Results have implications for hypotheses about duration experience.     

Visual memory for colour

Two colours were either simultaneously or successively presented. In both cases the time taken to determine whether the colours differed increased as the visual similarity of the colours increased. In another experiment, colours or names of colours were presented successively in different blocks of trials. Here colour similarity affected the discrimination reaction times whenever the second stimulus was a colour. This was taken to suggest that visual mnemonic representations can be generated from the first stimulus.     

Very long term memory for tacit knowledge

Very long term memory for abstract materials was examined by recalling subjects who had served in a synthetic grammar learning experiment two years earlier. In that study (Reber & Allen, 1978) we differentiated among several cognitive modes of acquisition, their resultant memorial representations, and their associated decision processes. Two years later and without any opportunity for rehearsal or relearning, subjects still retain knowledge of these grammars to a remarkable degree. Although some differences have become blurred with the passage of time, the form and structure of that knowledge and the manner in which it is put to use remain strikingly similar to the original. That is, differences traceable to acquisition mode and conditions of initial training can still be observed. As in the original study, these results are discussed within the general context of a functionalist approach to complex cognitive processes.     

Acquisition of basic object categories

Two implications of best-example theory for category acquisition were considered. The first is that categories which people acquire based on initial exposure to good exemplars should be learned more easily and (at first) more accurately than categories based on initial exposure to poor exemplars. The second is that people should generally learn that the best exemplars are category members, before learning that the poor exemplars are category members. These implications are based on the premise that people generalize based on similarity, and that the best example has maximal within-category similarity and minimal extra-category similarity, while the poor examples have minimal within-category similarity and relatively high extra-category similarity. Both implications were strongly supported by the present research. It was also found that when pressure to communicate was removed, comprehension and production of category names were virtually identical. The predictions of best-example theory concerning the conceptual structures underlying the words used by children who are just beginning to talk were discussed briefly. This research also allowed the replication of several important categorization results which had previously been found with real-world categories, with a set of artificial concrete object categories.     

Attention and automaticity in Stroop and priming tasks: Theory and data

Three major variables identified with attention and automaticity in the priming paradigm are shown to have parallel effects in the Stroop paradigm. A model is developed to explain the effects in both paradigms in terms of a single decision process that combines evidence from several sources (e.g., habitual associations and temporary contingencies between the prime and the target or between the unreported and reported dimensions). The model is applied to two Stroop experiments in which the faster two of three stimulus dimensions relate associatively and cue through a frequency manipulation the third, which must be reported. Depending on the direction of the cueing relation, attentional effects enhanced or counteracted automatic (associative) effects, and the attentional effects were stronger with the faster unreported dimension than with the slower one. These results corroborate findings in the priming paradigm and confirm the model. Implications of the results and the model for broader issues are discussed.     

Identifying the speech codes

Models of speech processing typically assume that speech is represented by a succession of codes. In this paper we argue for the psychological validity of a prelexical (phonetic) code and for a postlexical (phonological) code. Whereas phonetic codes are computed directly from an analysis of input acoustic information, phonological codes are derived from information made available subsequent to the perception of higher order (word) units. The results of four experiments described here indicate that listeners can gain access to, or identify, entities at both of these levels. In these studies listeners were presented with sentences and were asked to respond when a particular word-initial target phoneme was detected (phoneme monitoring). In the first three experiments speed of lexical access was manipulated by varying the lexical status (word/nonword) or frequency (high/low) of a word in the critical sentences. Reaction times (RTs) to target phonemes were unaffected by these variables when the target phoneme was on the manipulated word. On the other hand, RTs were substantially affected when the target-bearing word was immediately after the manipulated word. These studies demonstrate that listeners can respond to the prelexical phonetic code. Experiment IV manipulated the transitional probability (high/low) of the target-bearing word and the comprehension test administered to subjects. The results suggest that listeners are more likely to respond to the postlexical phonological code when contextual constraints are present. The comprehension tests did not appear to affect the code to which listeners responded. A “Dual Code” hypothesis is presented to account for the reported findings. According to this hypothesis, listeners can respond to either the phonetic or the phonological code, and various factors (e.g., contextual constraints, memory load, clarity of the input speech signal) influence in predictable ways the code that will be responded to. The Dual Code hypothesis is also used to account for and integrate data gathered with other experimental tasks and to make predictions about the outcome of further studies.     

The demonstration of capacity limitation

The study of divided attention has produced many apparent demonstrations of “capacity limitation.” Possible ambiguities in such demonstrations are considered for three major types of experimental situation: simultaneous inputs with separate responses; choice; and classification. Two issues emerge. First, demonstrations always rest on assumptions about process set, i.e., the set of internal processes by which the task actually is performed. Alternative process sets are considered for situations of each type. Second, a demonstration of capacity limitation is made either by increasing the number of simultaneous processes, or by changing the bias between them. In either case effects unrelated to capacity limitation may influence the results. If several processes contribute to a single response, some performance decrement must accompany an increase in their number, simply through the increased overall chance for error. If the subject is biased toward one alternative in a choice or classification situation, the benefits enjoyed by this alternative may reflect not a preferential allocation of attentional capacity, but simply a willingness to decide in favor of this alternative with relatively little evidence.     

Patterns of desynchrony in agoraphobia: A preliminary report

Changes in heart rate in three moderate to severe agoraphobic women were monitored by a Holter Recorder, used for obtaining portable EKGs. These data were collected before, half-way through, and at the end of a 12 session, group therapy program consisting of exposure and cognitive restructuring while subjects walked, or in one case, were driven along a standard 1.2 km course leading away from the treatment setting. Self-reports of anxiety were collected simultaneously. Despite substantial behavioral improvement in all cases, markedly different patterns of synchrony or desynchrony were noted between heart rate and self-reports of anxiety and substantial increases in heart rate were noted in one subject.     

Anxiety management and applied relaxation in reducing general anxiety

Sixty-three generally anxious subjects were assigned to anxiety management training, applied relaxation training, relaxation-only, placebo and untreated control conditions. After 6 weeks of treatment, anxiety management training led to reductions on a variety of self-report measures of state and trait anxiety and decreases in maladaptive cognitions during a laboratory stress procedure. On several measures, subjects in anxiety management training differed from relaxation-only and placebo subjects as well as untreated controls. However, treatment effects did not extend to performance and physiological measures of anxiety. Applied relaxation training, which in contrast to anxiety management training lacks structured rehearsal involving the recognition and reduction of tension cues during the treatment sessions, resulted in less consistent decreases in measures of general anxiety.