Category Use in Abstract Mental Comparisons

A recent model proposes that at least two processes are involved in mental comparisons; use of analogue and use of category information. The evidence that category information is used is not strong, however. It comes mainly from studies which had subjects overlearn the objects associated with arbitrary categories in the laboratory, and which used concrete dimensions. In the present study, two experiments were conducted to see if subjects spontaneously use natural categories from an abstract dimension (occupational status) in mental status comparisons. Subjects scaled occupations into status categories before each experiment and then compared the status of within-category and between-category occupation pairs. Within-category status comparisons reliably took longer than between-category ones of the same distance, suggesting that natural status categories were used.

The Effects of Helplessness Manipulations on Perceptual Responding: A Signal Detection Theory Analysis

This study was concerned with examining the effects of helplessness pre-treatment on performance in a perceptual task. Predictions from two different classes of helplessness hypothesis were considered. Cognitive hypotheses, such as the learned helplessness theory (Abramson, Seligman and Teasdale, 1978; Alloy and Seligman, 1979) suggest that the locus of helplessness effects is found in biases of perceptual and/or expectational mechanisms involved in analysing response-outcome events. These concepts were related to signal detection theory (SDT) and the predictions were that d’ and/or beta would vary as a function of helplessness exposure. In contrast, noncognitive hypotheses (Costello, 1978; Roth, 1975) do not predict that any differences would be reflected in either parameter. They merely stipulate that response factors are influenced by helplessness pre-treatment and do not require that any cognitive mechanisms be involved in producing the effects. Performance on a post-treatment orientation task was assessed using a SDT analysis following different helplessness pre-treatment. The analyses showed that neither d’ nor beta were affected by helplessness pre-treatment in the orientation task, even though the helplessness pre-treatment induced typical helplessness deficits in a parallel study using anagram solving as the post-treatment task. The only significant effects on the perceptual task were found in analyses of reaction times, with helpless individuals having faster responses. The results were most compatible with hypotheses suggesting that induced helplessness effects are the result of increasing levels of anxiety or arousal which affect performance factors such as responding time.

Bilingualism and Lexical Representation

Forty-eight Hindi-English bilinguals completed two blocks of trials where each trial involved presentation of a letter string requiring a lexical decision. In the first block subjects were exposed to 22 words and 11 non-words in either English or Hindi. In the second block the original words were repeated in either the same language or in the alternative language. In this block the old (repeated) words were mixed with 22 new words, and 22 non-words. Twelve subjects were included in each of the four groups given by the factorial combination of blocks and languages. Reaction time in the lexical decision task was facilitated when words were repeated in the same language (109 and 125 ms in the English-English and Hindi-Hindi groups respectively), but little or no facilitation was observed in the inter-lingual conditions (-22 and 23 ms in the Hindi-English and English-Hindi conditions respectively). The results support the view that lexical representation in bilinguals is language-specific.

Matching to Reinforcer Value: Human Concurrent Variable-Interval Performance

A male paedophile offender chose between pairs of sexual stimulus classes in a two-operandum procedure with reinforcement arranged according to concurrent variable-interval variable-interval schedules. Condition 1 involved choice between slides of women and slides of men; condition 2, slides of men vs. slides of children; and condition 3, slides of women vs. slides of children. On the assumption that the subject matched his ratios of responses and times on the two operanda to reinforcer value, estimates were obtained from the data in conditions 1 and 2 of the values of slides of women and of children relative to slides of men. These yielded predictions of the relative allocations of responses and of time in condition 3. The predicted and obtained outcomes were similar. The results support the use of matching-based scaling of reinforcer values in the prediction of choice between qualitatively different reinforcers and extend the application to a human subject, the two-operandum procedure, and sexual stimuli.

Short-Term Retention of “Surprising” Events by Pigeons

Terry and Wagner (1975) have suggested that the short-term retention of information about an event is enhanced if the occurrence of the event is made unexpected or surprising. Three experiments tested this idea using delayed conditional position (Experiment I) and colour discriminations (Experiments II and III). The subjects were pigeons and the presentation of food was the target event to be remembered. Choice of one of two simultaneously presented stimuli was reinforced if the retention interval had been initiated by presentation of target food. Contrary to Terry and Wagner's claim, retention was superior on probe test trials in Experiments I and II if the presentation of the target food was preceded by a previously established signal for food (CS+) rather than by a stimulus which had not been paired with food (CS-). Experiment III systematically manipulated the signalling conditions used during initial discrimination training. Retention was better following a CS+ presentation if the target food had been signalled during initial discrimination training but worse if the food presentation had been unsignalled. These results do not favour the idea that retention of an event is directly affected by whether or not the target event is surprising.

Short-Term Visual Recognition Memory in Pigeons

Recognition memory for lists of items was investigated in pigeons using a YES-NO recognition technique. Experiment I showed that increasing the exposure duration of the first item of a two-item list improved recognition for that item without impairing recognition of the second item. Experiment II showed that decreasing the inter-trial interval had no effect on correct YES responses but significantly increased the number of false YES responses. Experiment III showed that recognition for the last two items of a three-item list was no poorer than that for lists of only two items. Experiment IV showed that increasing the delay between presentation and test of a two-item list (from 0·25-1 s) had a more disruptive effect on recognition for the second than for the first item. The data from these four experiments support a model proposed by Roberts and Grant, according to which memory traces are independent, and decay as a negatively accelerated function of time. Experiments V, VI, and VII investigated recognition for lists of three, four, and five items, and found no evidence for a primacy effect, performance being a linear function of time since sample offset.

Letter Interactions in Brief Visual Displays

Three experiments were conducted to examine the influence of non-target letters on target detection performance. It was hypothesised that letters which are similar would exert a stronger masking influence on each other than letters which have a low level of feature similarity. The results indicate, however, that every letter has the same inhibitory potential regardless of its similarity rating to other letters. The highly significant letter interactions which did occur in the study were interpreted as evidence for an additive, rather than a subtractive, influence by the non-targets. It is proposed that when a target has an ambiguous identity, due to an impoverished representation, it may be disambiguated by the addition of feature information from the immediate letter context. The effect of filling in the target representation with a feature value from a non-target letter will be to weight the final representation towards the target which has the value most similar to the one substituted. In a sense, then, non-targets which are similar to a target can actually enhance target detection scores.