Mark Haselgrove

The influence of reading speed and line length on the effectiveness of reading from screen

With such a large volume of material accessible from the World Wide Web, there is an urgent need to increase our knowledge of factors influencing reading from screen. We investigate the effects of two reading speeds (normal and fast) and different line lengths on comprehension, reading rate and scrolling patterns. Scrolling patterns are defined as the way in which readers proceed through the text, pausing and scrolling. Comprehension and reading rate are also examined in relation to scrolling patterns to attempt to identify some characteristics of effective readers. We found a reduction in overall comprehension when reading fast, but the type of information recalled was not dependent on speed. A medium line length (55 characters per line) appears to support effective reading at normal and fast speeds. This produced the highest level of comprehension and was also read faster than short lines. Scrolling patterns associated with better comprehension (more time in pauses and more individual scrolling movements) contrast with scrolling patterns used by faster readers (less time in pauses between scrolling). Consequently, effective readers can only be defined in relation to the aims of the reading task, which may favour either speed or accuracy.

Reconciling the influence of predictiveness and uncertainty on stimulus salience: a model of attention in associative learning

Theories of selective attention in associative learning posit that the salience of a cue will be high if the cue is the best available predictor of reinforcement (high predictiveness). In contrast, a different class of attentional theory stipulates that the salience of a cue will be high if the cue is an inaccurate predictor of reinforcement (high uncertainty). Evidence in support of these seemingly contradictory propositions has led to: (i) the development of hybrid attentional models that assume the coexistence of separate, predictiveness-driven and uncertainty-driven mechanisms of changes in cue salience; and (ii) a surge of interest in identifying the neural circuits underpinning these mechanisms. Here, we put forward a formal attentional model of learning that reconciles the roles of predictiveness and uncertainty in salience modification. The issues discussed are relevant to psychologists, behavioural neuroscientists and neuroeconomists investigating the roles of predictiveness and uncertainty in behaviour.

The effects of reading speed and reading patterns on the understanding of text read from screen

With increasing use of the World Wide Web, rapid scanning or skimming of material on screen has become a frequent activity. However, the outcome of this method of reading has not been thoroughly investigated. Using a range of question types, comprehension was measured after reading from screen at both a normal and fast reading speed. In addition, by automatically recording how readers scrolled through each document, reading patterns were explored. A speed-accuracy trade-off was found and, in general, the recall of specific details was less accurate than responses to ‘higher order’ questions. However, questions that addressed the structure of the text were hardest. Analysis of the scrolling movements showed that the overall time spent pausing between movements was the best predictor of comprehension. At a normal reading speed, the most effective readers, in terms of higher comprehension scores, were those who spent more time between scrolling movements, which were fast and frequent.

A partial reinforcement extinction effect despite equal rates of reinforcement during Pavlovian conditioning.

In 4 experiments rats received appetitive Pavlovian conditioning followed by extinction. Food accompanied every trial with the conditioned stimulus (CS) for the continuously reinforced groups and only half of the trials for the partially reinforced groups. In contrast to previous experiments that have compared the effects of partial and continuous reinforcement, the rate at which food was delivered during the CS was the same for both groups. The strength of the conditioned response during extinction weakened more rapidly in the continuously than in the partially reinforced groups. The results demonstrate that the partial reinforcement extinction effect is a consequence of the nonreinforced trials with the CS, rather than the rate at which the unconditioned stimulus is delivered during the CS.

Automatic imitation in budgerigars.

A fully automated procedure, involving computer-controlled stimulus presentation and computer-recorded response measurement, was used for the first time to study imitation in non-human animals. After preliminary training to peck and step on a manipulandum, budgerigars were given a discrimination task in which they were rewarded with food for pecking during observation of pecking and for stepping during observation of stepping (Compatible group), or for pecking while observing stepping and for stepping while observing pecking (Incompatible group). The Incompatible group, which had to counter-imitate for food reward, showed weaker discrimination performance than the Compatible group. This suggests that, like humans, budgerigars are subject to ‘automatic imitation’; they cannot inhibit online the tendency to imitate pecking and/or stepping, even when imitation of these behaviours interferes with the performance of an ongoing task. The difference between the two groups persisted over 10 test sessions, but the Incompatible group eventually acquired the discrimination, making more counter-imitative than imitative responses in the final sessions. These results are consistent with the associative sequence learning model, which suggests that, across species, the development of imitation and the mirror system depends on sensorimotor experience and phylogenetically ancient mechanisms of associative learning.

The nature of discrimination learning in pigeons

The results from five experiments are considered in relation to two of Spence’s (1937, 1938) proposals concerning discrimination learning. In Experiments 1 and 2, we investigated whether his ideas about the interaction between excitatory and inhibitory generalization gradients can be used to understand how animals solve a complex patterning discrimination. The results supported a development of his proposals as put forward by Pearce (1994), provided a modification was made to Pearce’s rule for determining the shape of the generalization gradient. In Experiments 3, 4, and 5, we examined whether animals would pay more attention to stimuli that are relevant, rather than irrelevant, to the solution of a discrimination. The results supported this proposal for stimuli comprising visual patterns, but not for those comprising plain colors. The results also indicated that change of attention was a consequence of preliminary receptor-exposure acts, as envisaged by Spence, and not of more central changes in attention.

Two kinds of attention in Pavlovian conditioning: evidence for a hybrid model of learning.

Four appetitive Pavlovian conditioning experiments with rats examined the rate at which the discrimination between compounds AY and AX was solved relative to the discrimination between compounds AY and BY. In Experiments 1 and 2, these discriminations were preceded by training in which A and B were continuously reinforced and X and Y were partially reinforced. Consistent with the Pearce and Hall (1980) model, the results showed that the AY/AX discrimination was solved more readily than the AY/BY discrimination. In Experiments 3 and 4, the discriminations were preceded by feature-positive training in which trials with AX and BY signaled food but trials with X and Y did not. Consistent with the Mackintosh (1975) model, the results showed that the AY/BY discrimination was solved more readily than the AY/AX discrimination. These results are discussed with respect to a hybrid model of conditioning and attention.

The effects of hippocampal system lesions on a novel temporal discrimination task for rats

A novel, appetitive, Pavlovian conditioning task was used to assess interval timing. Experiment 1 showed that normal rats could discriminate between tones of 1.5s and 0.5s duration, or between tones of 12.0 s and 3.0 s duration. Learning was demonstrated by a greater duration of magazine responding in the period before the delivery of a food reward and after cessation of the CS+ compared to the same time period after cessation of the CS-. Learning was, however, asymmetric as it was much quicker when the CS+ was the longer of the two durations (1.5s and 12.0 s, respectively). Experiment 2 assessed the impact of fornix lesions on the acquisition of one version of this task (CS+ 1.5s, CS- 0.5s). No evidence was found of a change in discrimination learning following surgery. Experiment 3 examined whether rats with either fornix or hippocampal lesions affected discriminations between 12.0 s and 3.0 s stimuli. Again, there was no evidence of a lesion-induced deficit. T-maze alternation training confirmed the effectiveness of these lesions. The results not only reveal that neither the fornix nor the hippocampus is necessary for distinguishing temporal intervals within the ranges tested but also showed how under some circumstances these lesions can leave trace conditioning intact.

Facilitation of Extinction by an Increase or a Decrease in Trial Duration

Five experiments examined the effects of altering the duration of a conditioned stimulus (CS) for extinction. For the first 3 experiments, rats received conditioning with a 10-s CS before different groups received extinction with a CS that was either the same duration or longer than that used for conditioning. For the remaining 2 experiments, conditioning was conducted with a 60-s CS before different groups received extinction with a CS of either the same duration or a shorter duration than that used for conditioning. In all experiments, extinction progressed more readily when the CS duration was different for the 2 stages than when it was constant. The results are discussed in terms of rate expectancy theory and associative learning theory.

Failure of retrospective revaluation to influence blocking.

In the blocking paradigm, subjects receive reinforced presentations of a compound, AX, after reinforced presentations of A alone. Following this training, responding to X is often diminished relative to a control group, which did not receive the prior training with A. Standard associative theories of learning such as the Rescorla-Wagner model (Rescorla & Wagner, 1972) explain this effect by assuming that A and X compete for control over behavior. In contrast, theories such as the comparator hypothesis assume that learning about X is unaffected by the properties of A, but it is the expression of this learning at test that is affected by the blocking manipulation. The aim of the 3 reported experiments was to distinguish between these 2 accounts. According to the comparator hypothesis, devaluing A following blocking should increase subsequent responding to X. In all 3 experiments the blocking effect was found to persist following devaluation of A, providing support for standard associative theories.