Directed forgetting for categorised pictures: recognition memory for perceptual details versus gist

ABSTRACT

Item-based directed forgetting (DF) was tested using 2-alternative forced-choice recognition to examine the effects of forgetting instructions on memory for perceptual detail and gist of categorised pictures of scenes and objects in three experiments. When the distractor is from the same category as the target (exemplar test condition), discrimination must be based on memory for perceptual details, whereas recognition can be based on gist or general category information when the distractor is from a novel category (novel test condition). Recognition accuracy was greater for Remember-cued than Forget-cued pictures when discrimination must be based on perceptual details in the exemplar test condition but not when discrimination could be based on gist in the novel test condition. Accuracy in scene and object recognition is greater for gist than for perceptual details, and DF instructions serve to reduce recognition memory based on perceptual details.     

Introspective reports of reaction times in dual-tasks reflect experienced difficulty rather than timing of cognitive processes

Reports of introspective reaction times (iRTs) have been used to investigate conscious awareness during dual-task situations. Previous studies showed that dual-task costs in RTs (the psychological refractory period, PRP, effect) are not reflected in participants’ introspective reports. This finding has been attributed to conscious awareness of Task 2 being delayed while Task 1 is centrally processed. Here, we test this Temporal model and compare it to an alternative that assumes participants base their iRTs on experienced difficulty. We collected iRTs and difficulty estimates after each trial of a PRP paradigm in which the perceptual difficulty of either Task 2 (Experiment 1) or Task 1 (Experiment 2) was manipulated. Our results largely support the difficulty-based account, suggesting that in a dual-task situation, iRTs do not reflect timing of cognitive processes but are strongly influenced by the experience of difficulty.     

An organizational analysis of the form class effect

The paper reports eight experiments concerning the form class effect. If verb connectives enhance organization between pairs of nouns more than do conjunction connectives, then (a) the form class effect should obtain in cued but not free recall, (b) interactive imagery instructions should raise performance with conjunctions, removing the effect, (c) separation imagery instructions should reduce performance with verbs, removing the effect, and (d) prepositions implying spatial contact should be superior as mediators for cued recall compared with less suggestive prepositions. The results of the experiments confirm the predictions, except that grade 3 children do not perform as expected with the instructional variables.     

Short-term memory,verbal competence,and age as predictors of imagery instructional effectiveness

Children 6 to 11 years of age heard concrete sentences that they were asked to learn. Half the subjects were instructed to construct images representing the sentence meanings. The remaining participants were provided no strategy instructions (control condition). Consistent with previous outcomes, the older children in the imagery condition learned signficantly more than did the older control subjects. There was a slight trend favoring imagery for younger children in the sample. Individual differences in short-term memory and verbal competence were more highly associated with performance in the imagery than in the control condition, such that greater short-term memory and verbal competence predicted better sentence learning in the imagery condition. In particular, short-term memory and verbal competence made unique contributions (relative to age and to each other) to prediction of sentence learning in the imagery condition, but not in the control condition. In short, imagery instruction is more effective with children who are more intellectually competent.     

The role of imagery in incidental learning of educable retarded and normal children

Forty-five educable retarded and 45 normal children were given an orientation task in which noun- and picture-paired associates were presented once or four times under one of three instructional conditions: intentional imagery, incidental imagery, or intentional control (no imagery). An immediate associative recall test showed both imagery conditions to be superior to the intentional control condition. Furthermore, imagery instructions facilitated incidental recall of the retarded Ss equal to the recall of normal children in the intentional condition. Four presentations of pairs in contrast to one presentation during the orientation task improved the learning of both groups. The recall of retarded Ss in contrast to normal Ss, however, was greater with four presentations under imagery instructions than under intentional control instructions. The results were discussed in terms of imagery processes and their educational implications.     

Colour, face, and visuospatial imagery abilities in low-vision individuals with visual field deficits

This study investigates to what extent visual perception integrity is necessary for visual mental imagery. Sixteen low-vision participants with severe peripheral visual field loss, 16 with severe central field loss, 6 left brain-damaged patients with right homonymous hemianopia, 6 right brain-damaged patients with left homonymous hemianopia, and 16 normally sighted controls performed perceptual and imagery tasks using colours, faces, and spatial relationships. Results showed that (a) the perceptual and mental image>ry disorders vary according to the type of visual field loss, (b) hemianopics had no more difficulties imagining spatial stimuli in their contralesional hemispace than in their ipsilesional one, and (c) the only hemianopic participant to have perceptual and mental imagery impairments suffered from attentional deficits. Results suggest that (a) visual memory is not definitively established, but rather needs perceptual practice to be maintained, and (b) that visual mental imagery may involve some of the attentional-exploratory mechanisms that are employed in visual behaviour.     

Verifying different-modality properties for concepts produces switching costs

According to perceptual symbol systems, sensorimotor simulations underlie the representation of concepts. It follows that sensorimotor phenomena should arise in conceptual processing. Previous studies have shown that switching from one modality to another during perceptual processing incurs a processing cost. If perceptual simulation underlies conceptual processing, then verifying the properties of concepts should exhibit a switching cost as well. For example, verifying a property in the auditory modality (e.g., BLENDER-loud) should be slower after verifying a property in a different modality (e.g., CRANBERRIES-tart) than after verifying a property in the same modality (e.g., LEAVES-rustling). Only words were presented to subjects, and there were no instructions to use imagery. Nevertheless, switching modalities incurred a cost, analogous to the cost of switching modalities in perception. A second experiment showed that this effect was not due to associative priming between properties in the same modality. These results support the hypothesis that perceptual simulation underlies conceptual processing.     

Short-term memory differences between children predict imagery effects when sentences are read

Children in Grades 4 through 6 read concrete sentences that they were asked to learn. Half the subjects were instructed to construct images representing the sentence meanings. The remaining participants were provided no strategy instructions (control condition). Individual differences in short-term memory were more highly associated with performance in the imagery than in the control condition. There was a clear positive effect of imagery instructions on learning efficiency among students with relatively greater short-term memory; there was no difference in learning efficiency between the imagery and control conditions among students below the median for short-term memory performance. All relevant analyses supported the conclusion that imaginal coding of sentences that are read is demanding of short-term memory capacity.     

Unconscious sensations

D. M. Armstrong proposes to explain the possibility of unconscious sensations by means of a distinction between the perceptual consciousness, which is essentially involved in sensations, and our introspective consciousness of sensations. He holds that unconscious sensations are instances of perceptual consciousness of which we are not introspectively conscious. I contend that, although Armstrong's distinction is plausible and significant, it fails to explain his own examples of unconscious sensation. I argue that the puzzle of how unconscious sensations are possible arises at the level of perceptual consciousness and does not concern our introspective awareness of mental states.This paper grew out of research supported by the National Endowment for the Humanities at Cornell University in 1985. I would like to express my gratitude to the National Endowment, to Cornell, and to Sydney Shoemaker.     

Imagery and sentence mediators in verbal discrimination learning

The effect of instructions to use imagery and sentence strategies in verbal discrimination learning (VDL) was investigated in two experiments. In Experiment I, both imaging to and constructing a sentence for the correct item of each pair facilitated VDL relative to an uninstructed control condition. Incorporating both words of the pair into a compound image or compound sentence had no effect, a result that was replicated in Experiment It. Of the two compound instructions, only compound sentences consistently facilitated associative recall of the VDL pairs, suggesting that compound imagery instructions were not always adhered to by the Ss.     

Colour,face, and visuospatial imagery abilities in low-vision individuals with visual field deficits

This study investigates to what extent visual perception integrity is necessary for visual mental imagery. Sixteen low-vision participants with severe peripheral visual field loss, 16 with severe central field loss, 6 left brain-damaged patients with right homonymous hemianopia, 6 right brain-damaged patients with left homonymous hemianopia, and 16 normally sighted controls performed perceptual and imagery tasks using colours, faces, and spatial relationships. Results showed that (a) the perceptual and mental image>ry disorders vary according to the type of visual field loss, (b) hemianopics had no more difficulties imagining spatial stimuli in their contralesional hemispace than in their ipsilesional one, and (c) the only hemianopic participant to have perceptual and mental imagery impairments suffered from attentional deficits. Results suggest that (a) visual memory is not definitively established, but rather needs perceptual practice to be maintained, and (b) that visual mental imagery may involve some of the attentional–exploratory mechanisms that are employed in visual behaviour.     

Comparison processes on visual mental images

Three experiments were conducted to test whether visual mental images and visual perceptual representations possess equivalent structural properties and undergo functionally equivalent comparison processes. In Experiment 1, subjects were required to perform asame-different letter classification in which the two letters were shown in succession. The first letter in the pair either was actually presented (perceptual condition) or had to be actively generated (imaginal condition). Both conditions showed that (1) response latencies fordifferent decisions decreased as a function of the degree of difference (segment effect), and (2) same decisions were faster than the fastestdifferent ones (fast same effect). In Experiment 2, the imaginal condition only was employed, but no imagery instructions were given and very strict time constraints were assigned. In spite of these restrictions, subjects apparently generated and used visual images, as attested by the fact that the results were comparable to those of the previous experiment. In Experiment 3, three experimental manipulations were introduced to prevent the use of visual images. Such manipulations proved effective, as shown by the disappearance of the segment effect. It was concluded that in the visual modality images and percepts are equivalent in structure and are processed in a very similar way.     

Mental imagery and the distinction between primary and secondary memory

Previous research has shown that the imageability of stimulus material affects the secondary memory (SM) component of free recall, but not the primary memory (PM) component, and that a negative recency effect is only observed for material of high imageability. It was found that interactive imagery instructions affected the SM component, but not the PM component; separative imagery instructions led to an increased PM component and a reduced SM component. A negative recency effect can be observed in an initial, delayed recall test. However, it is removed by imagery mnemonic instructions. This supports the idea that the negative recency effect is caused by the fact that subjects do not normally image the last few words presented in a free-recall task.     

Viewing instructions impact emotional memory differently in older and young adults

The current study examines how the instructions given during picture viewing impact age differences in incidental emotional memory. Previous research has suggested that older adults' memory may be better when they make emotional rather than perceptual evaluations of stimuli and that their memory may show a positivity bias in tasks with open-ended viewing instructions. Across two experiments, participants viewing photographs either received open-ended instructions or were asked to make emotionally focused (Experiment 1) or perceptually focused (Experiment 2) evaluations. Emotional evaluations had no impact on older adults' memory, whereas perceptual evaluations reduced older adults' recall of emotional, but not of neutral, pictures. Evidence for the positivity effect was sporadic and was not easier to detect with open-ended viewing instructions. These results suggest that older adults' memory is best when the material to be remembered is emotionally evocative and they are allowed to process it as such.     

Children's use of imagery in accessing different types of semantic information

Semantic retrieval was examined in second graders under an induced imagery and a control condition. Two types of animal properties, perceptual and functional, were presented to children for verification. Properties were high and low in rated association strength; the size of the property (i.e., large vs small) was also manipulated in the case of perceptual meaning. Results suggest that young children rely on imagery in semantic retrieval; however, second graders are also adept at processing functional as well as perceptual meaning, and at using an abstract memory accessing system. Thus, considerable flexibility is evidenced by subjects in semantic retrieval.     

Shoemaker, Self–Blindness and Moore's Paradox

I show how the 'inner–sense' (quasi–perceptual) view of introspection can be defended against Shoemaker's influential 'argument from self–blindness'. If introspection and perception are analogous, the relationship between beliefs and introspective knowledge of them is merely contingent. Shoemaker argues that this implies the possibility that agents could be self–blind, i.e., could lack any introspective awareness of their own mental states. By invoking Moore's paradox, he rejects this possibility. But because Shoemaker's discussion conflates introspective awareness and self–knowledge, he cannot establish his conclusion. There is third–person evidence available to the self–blind which Shoemaker ignores, and it can account for the considerations from Moore's paradox that he raises.     

Effect of mental imagery on realizing affordances

Using a reaction time experiment, we examined whether imagining a response would lead to an increase in the frequency of its execution. During a pre-test and a post-test, participants had to respond as quickly as possible with either their left or their right hand, as they preferred, to the illumination of one of 17 target positions arrayed in front of them in a semicircle. Between these two phases, participants performed a practice condition. Each of 40 right-handed participants was assigned to one of four groups that differed in their practice condition: One group made only dominant-hand responses to all target locations, two imagery groups imagined dominant hand responses to all target locations, and the last group received a no-practice, control task. One imagery group received instructions emphasizing that imagery has a strong effect; the second group received instructions suggesting that imagery was not effective. The results showed an increased incidence of the practised response for both imagery groups during the post-test. No effect was found for the physical performance group and the control group. The change in performance for the imagery groups was not accompanied by a change in reaction time. The results are discussed in terms of imagining the realization of action possibilities and from a neuropsychological point of view.     

Einstein’s jacket: Evidence for long-term perceptual specificity in mental imagery

To what extent are visual fantasies constrained by our perceptual experience of the real world? Our study exploits the fact that people’s knowledge of the appearance of individuals from the early 20th Century (e.g., Albert Einstein, Winston Churchill) derives predominantly from viewing black-and-white media images. An initial experiment shows that mental imagery for individuals from this period are experienced as significantly less colourful than imagery for individuals from the era of colour media. A second experiment manipulated whether participants were instructed to explicitly imagine using colour or not (i.e., “imagine Albert Einstein wearing a green jacket” vs. “imagine Albert Einstein wearing a jacket”). Results show that colour manipulation only influences imagery for black-and-white era individuals, with no comparable effect on imagery for colour era individuals. This finding is replicated in a third experiment that includes an additional control condition of imagining generic characters (i.e., “Imagine a knight wearing a cloak” vs. “imagine a knight wearing a red cloak”). Again, only imagery for black-and-white era individuals is affected by the colour manipulation. Overall these results provide evidence for long-term perceptual specificity effects in mental imagery. We argue that visual fantasies can be constrained by surface features of underlying representations in memory, even when imagining something we have never directly perceived.