1. This study is a mixed 3 (Information Density) X 2 (Structural Complexity) x 4 (Message) x 4 (Order) design. Except for Order, all are within subject factors. Independent Variables Information Density 3 levels (Low, Medium & High) An index of the resources required for processing To calculate this we first totaled up the Auditory I 2 values of all the voice changes and onsets in each message. Then, for each PSA this total was divided by the message duration to arrive at an Auditory I2/second value. This was the operational definition of Information Density. The 24 messages were divided into three groups of 8 to create the 3 levels of the factor. Structural Complexity 2 levels (Low & High) An index of resources allocated to message processing. Within each level of information density, messages were divided into two groups representing the highest and lowest values of auditory structural onsets per second. Dependent Variables Emotional Arousal and Valence measured by the Self- Assessment Manikin (SAM; Bradley & P.J. Lang, 1994). Physiological Arousal assessed by skin conductance responses (SCRs). Cognitive Effort measured by change in heart rate over time. Encoding accessed by a forced-choice, four-alternative, multiple- choice recognition test Data Collection Structural Features in Earlier Studies Information Density and Structural Complexity in Audio Messages: Are Two Concepts Better than One? Robert F. Potter, Zheng Wang, Ashley Sanders-Jackson, Jacob Koruth, Satoko Kurita & Annie Lang Indiana University Study Design More Frequent Breaks Disturb Listeners More Negative Attitudes Greater Autonomic Arousal Participants 96 undergraduates (36 male, 56 female, 4 unspecified) and 72 tweens (32 male, 29 female, 1 unspecified ). Age ranged from 9 to 24. Procedure Each participant completed the experiment individually. They listened to 24 radio PSAs. Following each message, they rated how they felt during the message using SAM. After all 24 messages, they performed a distraction task and then took the recognition test. However, these are probably not valid assumptions. This study addresses the second assumption by introducing a new concept. Select Predictions & Results (There are more in the paper, have us email it to you!) The Limited Capacity Model of Motivated Mediated Message Processing (LC4MP) conceptualizes message processing as an interaction between a media user, a medium, and message content. Resources are allocated automatically as a function of medium and message structure and when content is motivationally relevant. Users allocate resources through decisions about what messages to engage with, how hard to work at them, etc. Message Processing as Resource Parsing Automatic resource allocation occurs via the orienting response (OR) during both visual (Lang et al, 1999) and auditory processing (Potter et al, 2001). These early studies made two assumptions respectively: 1.Some visual structural features always require more resources to process than others. For example, a cut would always require more resources than an edit. 2.Each auditory structural feature introduced the same amount of information for processing. Auditory Information Introduced (Auditory I 2 ) Identifies two common sets of auditory structural features and quantifies the relative amount of information needed to be processed by the resources automatically allocated to it. The Voice Change: For each voice change the following questions were asked: Is it a new voice, one I that hasn’t been heard before? Does it introduce unrelated content? Is there a change in auditory form across the voice change? Is there a change in form compared to the last time I heard this voice? Is there a change in ambient sound across the voice change? Is there a change in ambience compared to the last time I heard this voice? Is there an emotion change across the voice change? Structural Onsets: Sound effects, music onsets, production effects, silence, and emotional words For each onset the following questions were asked: Is this a new form of sound (i.e., have I heard this sound before)? Is it unrelated to what has happened in the message? Is it an emotionally intense sound? Is there a change in emotion caused by the sound? When resources allocated by structural complexity are greater than resources required by information density, recognition will increase. When those required surpass those allocated, the system will overload and recognition will decrease. Prior to overload cognitive effort will increase (lower heart rates) with increases in structural complexity. As overload occurs, listeners will disengage from message processing, and heart rates will increase. Disengagement from message processing will not impact physiological arousal levels, however, which will increase with increases in structural complexity.