Examining the Response Competition Hypothesis of Age Effects in Implicit Memory

ABSTRACT

Age reductions in priming have been explained by differences in processing demands across implicit memory tests. According to one hypothesis, older adults show reduced priming relative to younger adults on implicit tests that require production of a response because these tests typically allow for response competition. In contrast, older adults do not show reductions in priming on identification tests that contain little response competition. The following experiments tested the specific role of response competition in mediating age effects in implicit memory. In Experiment 1, younger and older adults studied a list of words and were then given an implicit test of word stem completion. They studied a second list of words and were given an implicit test of general knowledge. Each implicit test contained items with unique solutions (the low response competition condition) and items with multiple solutions (the high response competition condition). In Experiment 2, younger and older adults were given explicit versions of the word stem completion and the general knowledge tests. Results showed an effect of age on explicit memory (Experiment 2), but no effect of age or response competition on priming (Experiment 1). Results are inconsistent with the theory that response competition leads to age effects on production tests of implicit memory.     

On the timescale of stimulus-based action–effect learning

When performing an action, people pick up associations between their actions and the resulting consequences of that action, a phenomenon that has been termed response (R)–effect (E) learning. In the present study, we investigated incidental R–E learning in a forced-choice—that is, a stimulus (S)-based—acquisition mode. Specifically, the study examined at which timescale R–E learning evolves—that is, how many encounters are actually needed to form stable R–E associations. The learning of R–E associations was assessed in a subsequent test phase via effect-based response priming. Experiment 1 tested 4 different numbers of S–R–E repetitions for a 2–2–2 S–R–E mapping. Experiment 2 disentangled the contributions of S–E and R–E associations to the facilitating impact of effect-based response priming by means of a 4–2–4 S–R–E mapping. Experiment 3 investigated whether R–E associations can be picked up even when a given E cannot be unequivocally predicted based on the antecedent S in case of inconsistent S–R–E couplings. Together, the results of the present study clearly show that R–E learning occurs in a stimulus-based action mode and that it evolves very rapidly after only 12 S–R–E repetitions. Moreover, the present findings suggest that at least in this initial phase of learning, complete S–R–E consistency seems to be relevant for R–E learning.     

Perceptual and response components in repetition priming of spoken words and pseudowords

Two experiments explored repetition priming effects for spoken words and pseudowords in order to investigate abstractionist and episodic accounts of spoken word recognition and repetition priming. In Experiment 1, lexical decisions were made on spoken words and pseudowords with half of the items presented twice (～12 intervening items). Half of all repetitions were spoken in a “different voice” from the first presentations. Experiment 2 used the same procedure but with stimuli embedded in noise to slow responses. Results showed greater priming for words than for pseudowords and no effect of voice change in both normal and effortful processing conditions. Additional analyses showed that for slower participants, priming is more equivalent for words and pseudowords, suggesting episodic stimulus–response associations that suppress familiarity-based mechanisms that ordinarily enhance word priming. By relating behavioural priming to the time-course of pseudoword identification we showed that under normal listening conditions (Experiment 1) priming reflects facilitation of both perceptual and decision components, whereas in effortful listening conditions (Experiment 2) priming effects primarily reflect enhanced decision/response generation processes. Both stimulus–response associations and enhanced processing of sensory input seem to be voice independent, providing novel evidence concerning the degree of perceptual abstraction in the recognition of spoken words and pseudowords.     

Response-level probability effects on reaction time: Now you see them,now you don't

Many reaction time (RT) experiments have tested for response-level probability effects. Their results have been mixed, which is surprising because psychophysiological studies provide clear evidence of motor-level changes associated with an anticipated response. A survey of the designs used in the RT studies reveals many potential problems that could conceal the effects of response probability. We report five new RT experiments testing for response-level probability effects with the most promising of the previous designs—that of Blackman (1972 Blackman, A. R. 1972. Influence of stimulus and response probability on decision and movement latency in a discrete choice reaction task. Journal of Experimental Psychology, 92: 128–133. doi:10.1037/h0032169[Crossref], [PubMed] , [Google Scholar])—and with new designs. Some of these experiments yield evidence of response-level probability effects, but others do not. It appears that response-level probability effects are present primarily in simple tasks with a strong emphasis on response preparation, possibly because participants only expend effort on response preparation in these tasks.     

Blinded by fear? Prior exposure to fearful faces enhances attentional processing of task-irrelevant stimuli

Threatening information has been shown to both capture attention and enhance sensory processing. Recent evidence has also suggested that exposure to fearful stimuli may enhance perceptual processing of subsequently presented information, as well as increase attentional capacity. However, these results are inconsistent with other findings that fearful stimuli reduce task-irrelevant distraction and improve selective attention. Here, we investigated the effect of prior exposure to fearful faces on performance in the Eriksen flanker task. Across experiments, fearful cues led to increased task-irrelevant distraction for items positioned across visual space, in contrast to other emotional expressions and inverted face items, and under conditions of attentional load. Findings support the view that fearful images enhance attentional capacity, allowing one to attend to as much visual information as possible when danger is implied. Conflicting findings on the effect of fear and selective attention are discussed.     

Mug handle affordance and automatic response inhibition: Behavioural and electrophysiological evidence

Behavioural evidence has shown that the perception of an object's handle automatically activates the corresponding action representation. The activation appears to be inhibited if the object is a task-irrelevant prime mug that is presented very briefly prior to responding to the target arrow. The present study uses an electrophysiological indicator of automatic response priming, the lateralized readiness potential (LRP), to investigate the mechanisms of this inhibition effect. We presumed that this effect would reflect motor self-inhibition processes. The self-inhibition explanation of the effect would assume that the effect reflects activation-followed-by-inhibition observed rapidly after the offset of the prime at the primary motor cortex. However, the results showed that the effect is not associated with modulation of the early LRP deflections. In contrast, the inhibition manifested itself in the later LRP deflections that we assume to be linked to interference in the processing of response-related aspects of the target. We propose that the LRP pattern is similar to what would be predicted from the negative priming explanation of the effect. The study sheds light on understanding inhibition mechanisms associated with automatically activated affordance representations.     

Additivity neglect in probability estimates: Effects of numeracy and response format

When people are asked to estimate the probabilities for an exhaustive set of more than two events, they often produce probabilities that add up to more than 100%. Potential determinants for such additivity neglect are explored in four experiments. Additive responses vary between experimental conditions, mainly as a result of response format, with a scale format leading to fewer additive responses than a list format with self-generated, written probabilities. Participants with high numeracy scores produced more additive responses, especially after being primed with a numeracy scale. Additivity neglect for 100% sums appears to be unrelated to other subadditive judgments, like non-additive disjunctions. We conclude that additivity neglect is caused by a case-based approach, which comes natural in real-life situations where the full set of outcomes is not available.     

Avoiding the problem state bottleneck by strategic use of the environment

We investigated whether environmental support can be used to circumvent the problem state bottleneck in human multitasking. Previously, it was shown that people can only maintain a single chunk of information in their problem state resource, the central part of working memory. Consequently, when the problem state resource was required by multiple tasks concurrently, performance decreased. This phenomenon was termed the problem state bottleneck. To investigate whether the environment can be used to circumvent this bottleneck, we conducted an experiment with two main conditions. In the No-Support condition we replicated an earlier experiment that indicated the existence of the problem state bottleneck. In the Support condition we presented external cues, reducing the load on the problem state resource. To support the results of the experiment we present a computational cognitive model. The experiment and model indicated that the problem state bottleneck can be avoided by using external cues. However, subjects only used external cues when this led to faster behavior. These results were interpreted in the light of the Soft Constraints Hypothesis, which states that humans always follow the fastest strategy possible, as opposed to the most accurate strategy.     

Event-method directed forgetting: Forgetting a video segment is more effortful than remembering it

Videos were presented depicting events such as baking cookies or cleaning a fish tank. Periodically, the video paused and an instruction to Remember (R) or Forget (F) the preceding video segment was presented; the video then resumed. Participants later responded more accurately to cued-recall questions (E1) and to true/false statements (E2–5) regarding R segments than F segments. This difference was larger for specific information (the woman added 3 cups of flour) than for general information (the woman added flour). Participants were also slower to detect visual probes presented following F instructions compared to those presented following R instructions. These findings suggest that intentional forgetting is an effortful process that can be performed even on segments of otherwise continuous events and that the result is a relatively impoverished representation of the unwanted information in memory.     

The time course of temporal preparation in an applied setting: A study of gaming behavior

We examined the time course of temporal preparation in the practice of computer gaming. Participants held an infrared rifle to shoot animated figures (“terrorists”) that appeared from an elevator that opened briefly after the sound of a bell. The sound was either loud or soft and the interval between the sound and the opening of the elevator varied between 100 and 600 ms. We found that shooting latency decreased exponentially as a function of interval, reflecting growing temporal preparation towards an optimum. When the sound was soft, this function was shifted to the right as compared to when the sound was loud. These findings are consistent with a model assuming that preparation starts upon the detection of a warning (i.e., later for the soft than for the loud sound) and continues until the detection of a target (i.e., longer as the interval increases). These results signify a successful application of a theoretical model in an applied setting.